Technical Service Training

Technical Service Training

Diesel Injection and EngineManagement Systems

Common Rail Systems

CG 8258/S en 01/2008TC304 3 060H

To the best of our knowledge, the illustrations, technical information, data and descriptions in this issue were correct at the timeof going to print. The right to change prices, specifications, equipment and maintenance instructions at any time without noticeis reserved as part of FORD policy of continuous development and improvement for the benefit of our customers.

No part of this publication may be reproduced, stored in a data processing system or transmitted in any form, electronic,mechanical, photocopy, recording, translation or by any other means without prior permission of Ford-Werke GmbH. No liabilitycan be accepted for any inaccuracies in this publication, although every possible care has been taken to make it as complete andaccurate as possible.

Copyright ©2008

Ford-Werke GmbHService training programs D-F/GT1 (GB)

More stringent exhaust and noise emission standards and calls for lower fuel consumption continue to place newdemands on the fuel injection and engine management systems of diesel engines.

In order to satisfy these requirements, the injection system must inject the fuel at high pressure into the combustionchamber to provide good mixture preparation and, at the same time, meter the injected fuel quantity with the highestpossible accuracy. The common rail system offers good potential for development, which is of particular significanceboth now and in the future. By separating the pressure generation process from the injection process, the optimuminjection pressure is always available for the injection process, regardless of engine speed.

Modern engine management systems ensure that the fuel injection timing and injected fuel quantity are exactlycalculated and delivered to the engine cylinders by the fuel injectors.

The following common rail systems are currently installed in Ford vehicles:

– Bosch common rail system,

– Siemens common rail system,

– Denso common rail system.

Another big step towards achieving cleanliness in diesel engines is the newly developed diesel particulate filtersystem. This system helps reduce micro-fine diesel particulates by up to 99%.

Completion of the eLearning program "Diesel Fuel Injection and Engine Management Systems" is a prerequisitefor the study of this Student Information.

This Student Information is divided into lessons. At the end of each lesson there is a set of test questions that aredesigned to monitor the student's progress. The solutions to these test questions can be found at the end of theStudent Information.

Please remember that our training literature has been prepared for FORD TRAINING PURPOSES only. Repairsand adjustments MUST always be carried out according to the instructions and specifications in the workshopliterature. Please make full use of the training offered by Ford Technical Training Courses to gain extensiveknowledge of both theory and practice.

1Service Training (G1008812)

Preface

Preface...............................................................................................................................

Lesson 1 – General Information6Overview of the systems...................................................................................................................................................

10Introduction.......................................................................................................................................................................

11Injection characteristics.....................................................................................................................................................

13Torque................................................................................................................................................................................

13Emission Standard IV with or without DPF......................................................................................................................

13Cleanliness when working on the common rail system....................................................................................................

14Test questions................................................................................................................................................

Lesson 2 – Fuel System15Overview...........................................................................................................................................................................

20Low-pressure system....................................................................................................................................

20General..............................................................................................................................................................................

21Bosch common rail system...........................................................................................................................

21Fuel filter...........................................................................................................................................................................

25Overview of the high-pressure system..............................................................................................................................

27Fuel pump..........................................................................................................................................................................

33Fuel rail (common rail)......................................................................................................................................................

33High-pressure fuel lines.....................................................................................................................................................

33Fuel injectors (general)......................................................................................................................................................

34Solenoid valve-controlled fuel injectors............................................................................................................................

37Piezo-controlled fuel injectors...........................................................................................................................................

42Siemens common rail system.......................................................................................................................

42Fuel filter...........................................................................................................................................................................


44Fuel pump..........................................................................................................................................................................

47Fuel rail and high-pressure fuel lines................................................................................................................................

48Fuel injectors.....................................................................................................................................................................

53Denso common rail system...........................................................................................................................

53Fuel filter...........................................................................................................................................................................


55Fuel pump..........................................................................................................................................................................

58Fuel rail and high-pressure fuel lines................................................................................................................................

60Fuel injectors.....................................................................................................................................................................

62Test questions................................................................................................................................................

Service Training2

Table of Contents

Lesson 3 – Powertrain Control Module (PCM)63General..............................................................................................................................................................................

63Input signals......................................................................................................................................................................

63Output signals....................................................................................................................................................................

64Diagnosis...........................................................................................................................................................................

65PCM and peripherals...................................................................................................................................

65Bosch common rail system................................................................................................................................................

69Siemens common rail system............................................................................................................................................

73Denso common rail system...............................................................................................................................................

75Strategies.......................................................................................................................................................

75Idle speed control..............................................................................................................................................................

75Fuel metering calculations.................................................................................................................................................

77Smooth-running control (cylinder balancing)...................................................................................................................

77External intervention into the injected fuel quantity.........................................................................................................

78Controlling fuel injection..................................................................................................................................................

79Controlling the fuel pressure.............................................................................................................................................

81EGR system.......................................................................................................................................................................

83Boost pressure control.......................................................................................................................................................

86EOBD.............................................................................................................................................................

86General..............................................................................................................................................................................

87Fault logging and storing...................................................................................................................................................

88Test questions................................................................................................................................................

Lesson 4 – Sensors89Introduction.......................................................................................................................................................................

89CKP sensor........................................................................................................................................................................

91CMP sensor.......................................................................................................................................................................

92MAP sensor.......................................................................................................................................................................

93IAT sensor..........................................................................................................................................................................

93MAPT sensor.....................................................................................................................................................................

94BARO sensor.....................................................................................................................................................................

94ECT sensor........................................................................................................................................................................

96CHT sensor (Kent and Puma diesel engines only)............................................................................................................

98Combined IAT sensor and MAF sensor............................................................................................................................

99HO2S.................................................................................................................................................................................

100Turbocharger position sensor (certain versions only).......................................................................................................

101Vehicle speed signal..........................................................................................................................................................

102APP sensor........................................................................................................................................................................

3Service Training

Table of Contents

103Fuel temperature sensor.....................................................................................................................................................

104Fuel pressure sensor..........................................................................................................................................................

105Engine oil level sensor (2.4L/3.2L Duratorq-TDCi (Puma) diesel engine)......................................................................

107Engine oil level sensor (2.2L Duratorq-TDCi (DW) diesel engine).................................................................................

109Oil pressure switch............................................................................................................................................................

109Stoplamp switch/BPP switch.............................................................................................................................................

110CPP switch........................................................................................................................................................................

111Test questions................................................................................................................................................

Lesson 5 – Actuators112Fuel metering valve...........................................................................................................................................................

114Fuel pressure regulator......................................................................................................................................................

116Fuel injectors (solenoid valve-controlled).........................................................................................................................

118Fuel injectors (piezo-controlled).......................................................................................................................................

119EGR valve.........................................................................................................................................................................

121Wastegate control valve (vacuum-controlled systems).....................................................................................................

122Intake manifold flap and intake manifold flap solenoid valve (vacuum-controlled systems)...........................................

123Intake manifold flap actuator motor (1.6L Duratorq-TDCi (DV) diesel engine, Emission Standard IV)........................

125Turbocharger variable vane electrical actuator..................................................................................................................

128Electric fuel pump (2.2L Duratorq-TDCi (DW) diesel engine only)................................................................................

129Test questions................................................................................................................................................

Lesson 6 – Engine Emission Control

130Introduction...................................................................................................................................................

130Pollutant emissions reduction............................................................................................................................................

130DPF (general)....................................................................................................................................................................

131Regeneration of the DPF (general)....................................................................................................................................

133DPF with fuel additive system.....................................................................................................................

133Component overview.........................................................................................................................................................

135DPF....................................................................................................................................................................................

136Charge air cooler bypass...................................................................................................................................................

138Fuel additive system – general..........................................................................................................................................

139Components of the fuel additive system...........................................................................................................................

141Component overview – system control.............................................................................................................................

143PCM...................................................................................................................................................................................

143Fuel additive control unit...................................................................................................................................................

144Fuel additive pump unit.....................................................................................................................................................

145Tank flap switch................................................................................................................................................................

146Exhaust gas temperature sensor(s)....................................................................................................................................

Service Training4

Table of Contents

147DPF differential pressure sensor ......................................................................................................................................

148Intake manifold flap actuator motors (Bosch system only)..............................................................................................

148Charge air cooler bypass flap actuator motor (Bosch system only)..................................................................................

150Intake manifold flap and charge air cooler bypass flap solenoid valves (Siemens system)..............................................

151Coated diesel particulate filter (DPF).........................................................................................................

151Overview of the DPF.........................................................................................................................................................

151Passive regeneration..........................................................................................................................................................

152Active regeneration............................................................................................................................................................

152Notes on the oil change interval........................................................................................................................................

153DPF regeneration indicator (2006.5 Transit only).............................................................................................................

153Intake manifold flap..........................................................................................................................................................

154Components of the engine emission control system.........................................................................................................

155Exhaust gas temperature sensor(s)....................................................................................................................................

155DPF differential pressure sensor ......................................................................................................................................

156Intake manifold flap position sensor (vacuum-controlled systems)..................................................................................

157Intake manifold flap unit...................................................................................................................................................

158Fuel vaporiser system...................................................................................................................................

158General..............................................................................................................................................................................

159Fuel vaporiser system fuel pump.......................................................................................................................................

160Fuel vaporiser....................................................................................................................................................................

161Test questions................................................................................................................................................

162Answers to the test questions...........................................................................................

163List of Abbreviations........................................................................................................

5Service Training

Table of Contents

Overview of the systems

Bosch common rail system with "solenoid valve-controlled" fuel injectors

E51104

(G1009902) Service Training6

Lesson 1 – General Information

Bosch common rail system with "piezo-controlled" fuel injectors

E96077



Siemens common rail system

E53583



Denso common rail system

E69955

Assignment of the common rail systems to the engines

DensoSiemensBoschEngine

X1.4L Duratorq-TDCi (DV)diesel

X1.6L Duratorq-TDCi (DV)diesel

X*1.8L Duratorq-TDCi (Kent)diesel



DensoSiemensBoschEngine

X2.0L Duratorq-TDCi (DW)diesel

X2.2L Duratorq-TDCi (DW)diesel

X*2.2L Duratorq-TDCi(Puma) diesel

X*2.4L Duratorq-TDCi(Puma) diesel

X3.2L Duratorq-TDCi(Puma) diesel

* Older versions are equipped with the Delphi common rail system. The Delphi common rail system is not part of this Student Information.

Introduction

Increasingly higher demands are being placed on moderndiesel engines. The focus today is not only on exhaustemissions but also on increasing environmentalawareness and the demand for increasingly bettereconomy and enhanced driving comfort.

This requires the use of complex injection systems, highinjection pressures and accurate fuel metering by fullyelectronically-controlled systems.

The high injection pressures convert the fuel, via theinjector nozzle, into tiny droplets, which, again due tothe high pressure, can then be optimally distributed inthe combustion chamber. This results in less unburnedHC (Hydrocarbon), less CO (Carbon Monoxide) andfewer diesel exhaust particulates being produced in thesubsequent combustion stage.

In addition, the optimised mixture formation reducesfuel consumption.

Diesel knock caused by the combustion process of anengine with direct injection is significantly reduced bymeans of additional pilot injection. NOX (Oxides OfNitrogen) emissions can also be reduced by using thismethod.

In particular, the demands placed upon the injectionsystem and its regulation are as follows for moderndiesel engines:

• high injection pressures,

• shaping of injection timing characteristics,

• multiple injections,

• values for injected fuel quantity, start of injectionand boost pressure adapted to every operatingcondition,

• load-independent idle speed control,

• closed-loop EGR (Exhaust Gas Recirculation),

• low injection timing and injected fuel quantitytolerances and high degree of precision over theentire service life,

• possibility of interaction with other systems such asstability assist, PATS (Passive Anti-Theft System),

• comprehensive diagnostic facilities,

• substitute strategies in the event of faults.

The common rail injection system has a large rangeof features to meet these demands.

In common rail injection systems, pressure generationis separate from the injection process. The injectionpressure is generated independently of engine speed andinjected fuel quantity.

The common rail injection system consists of ahigh-pressure pump and a fuel rail (fuelaccumulator/rail). This fuel rail offers constant pressurefor distributing fuel to the electrically-controlled fuelinjectors.

With this type of diesel injection or engine management,the driver has no direct influence on the injected fuelquantity. For example, there is no mechanical connection



between the accelerator pedal and the injection pump.The injected fuel quantity is determined by variousparameters. These include:

• driver demand (accelerator pedal position),

• operating condition,

• engine temperature,

• effects on exhaust emissions,

• prevention of engine and transmission damage,

• faults in the system.

Using these parameters, the injected fuel quantity iscalculated in the PCM (Powertrain Control Module)and fuel injection timing and injection pressure can bevaried.

The fuel is metered fully electronically by the PCM.

The fully electronic diesel engine management systemfeatures a comprehensive fail-safe concept (integratedin the PCM software). It detects any deviations andmalfunctions and initiates corresponding actionsdepending on the resulting effects (e.g. limiting thepower output by reducing the quantity of fuel).

Injection characteristics

As already mentioned at the beginning of the lesson,the exhaust emissions and fuel consumption of anengine are of great significance. These factors can onlybe minimised through precise operation of the injectionsystem and comprehensive engine managementstrategies.

Consequently, the following requirements must be metby the common rail system:

• The injection timing must be exact. Even smallvariations have a significant effect on fuelconsumption, exhaust emissions and combustionnoise.

• The fuel injection pressure is independently adaptedto all operating conditions.

• Injection must be reliably terminated. Calculationof the injected fuel quantity and the injection timingis precisely adapted to the mechanical componentsof the injection system. Uncontrolled fuel dribble(e.g. caused by a defective fuel injector) results inincreased exhaust emissions and increased fuelconsumption.

Simple main injection

Needle lift of the fuel injector nozzle and pressure curvein a cylinder without pilot injection

E64973

1

2

3

4

5

Combustion pressure in the cylinder1

Needle lift2

TDC (Top Dead Center)3

Needle lift with simple main injection4

Crankshaft angle5

In the case of diesel engines with a distributor-typefuel injection pump (e.g. in the Transit 2000.5), fuelinjection takes place via simple main injection.

The fuel is then injected mechanically into thecombustion chamber by the injector nozzles in twoseamlessly integrated stages (two-spring nozzle carrierprinciple).

In the pressure curve, the combustion pressure increasesonly slightly in the phase before TDC corresponding tocompression, but increases very sharply at the start ofcombustion.

The sharp pressure rise intensifies the combustion noise.



Pilot injection

Needle lift of the fuel injector nozzle and pressure curvein a cylinder with pilot injection

E64974

1

2

3

45

6


Needle lift2

TDC3

Needle lift with pilot injection4

Needle lift with main injection5

Crankshaft angle6

In the case of vehicles with a common rail injectionsystem, electrically-controlled pilot injection occursafter a set time prior to the main injection event.

Pilot injection means that a small amount of fuel isinjected into the cylinder prior to the main injection.

The small pilot-injection fuel quantity is ignited, heatsup the upper part of the cylinder and thereby brings itinto an optimum temperature range (preconditioning ofthe combustion chamber).

This means that the main injection mixture ignites morequickly and the rise in temperature and combustionpressure is less abrupt as a result.

Advantage:

• Continuous build-up of combustion pressure,resulting in reduced combustion noise.

• Reduction of oxides of nitrogen in the exhaust gas.

Note: As pressure generation and injection are separatein common rail systems, it is possible to considerablyenhance the range for pilot injection. This has led to asignificant improvement in the running smoothness ofthe engine.

With modern fuel injectors, it is also possible to workwith multiple pilot injections. The greater the numberof pilot injections, the lower the noise emissions.

Post-injection (vehicles with DPF (DieselParticulate Filter) system)

Needle lift of the injector nozzle with pilot andpost-injection

E51105

12

45 6

3

Needle lift1

Pilot injection2

Crankshaft angle3

Main injection4

Advanced post-injection5

Retarded post-injection6

For vehicles with a DPF (Diesel Particulate Filter)system, two post-injections are employed during theregeneration process, in addition to the pilot and maininjections, depending on the requirements.

Advanced post-injection is initiated in certainload/speed ranges immediately after main injection.Fuel is then injected during the on-going combustion.

The main purpose of this advanced post-injection is toraise the exhaust gas temperature during the regenerationprocess of the DPF. In addition, some of the dieselparticulates produced during regeneration areafter-burned.



Retarded post-injection only occurs shortly beforeBDC (Bottom Dead Center) and also serves to raise theexhaust gas temperature.

In contrast to advanced post-injection, during retardedpost-injection the fuel is not burned, but vaporises dueto the residual heat in the exhaust gas. This exhaust/fuelmixture is delivered to the exhaust system by the exhauststroke.

In the oxidation catalytic converter, the fuel vapourreacts with the residual oxygen (above a certaintemperature) and burns. This provides sustained heatingof the oxidation catalytic converter, which supports theregeneration of the DPF.

Torque

In general, diesel engines generate a high torque acrossa wide engine speed range. This is achieved throughuniformly good cylinder charging (working without athrottle plate) and high combustion pressure.

Overtorque function

On some vehicle versions, an overtorque function (alsocalled an overboost function) is used. This makes itpossible to briefly exceed the maximum specified torqueduring rapid acceleration (by about 15 to 35 Nmdepending on the calibration).

The short-term torque increase is an advantage whenovertaking, for example.

The vehicle acceleration is calculated based on thevehicle speed signal and the CKP (Crankshaft Position)sensor. During acceleration, the PCM activates theovertorque function in an engine speed range between1,700 and 3,500 rpm.

Emission Standard IV with or withoutDPF

At the time of going to press, Emission Standard IVapplies in Europe.

In the diesel sector, Emission Standard IV is achievedusing two different methods.

One method consists of reducing exhaust emissions bymeans of internal engine measures to the extent thatthe prescribed limits are met.

Measures for the reduction of exhaust emissions insidethe engine include, for example:

• further optimised exhaust gas recirculation by meansof an electrically-controlled EGR system with intakeair restriction,

• optimisation of the combustion chamber design andthe injection characteristics.

In addition to the internal engine measures, the secondmethod employs a DPF system.

The use of the DPF reduces diesel particulate emissionsby up to 99%. This reduction far exceeds therequirements for the European emission limits ofEmission Standard IV.

It can therefore be deduced that the use of the DPF willbe of great importance with regard to future emissionstandards, but is not absolutely necessary for meetingEmission Standard IV.

Cleanliness when working on thecommon rail system

NOTE: Because the components of the high-pressurefuel system are high-precision machined parts, it isessential that scrupulous cleanliness is observed whencarrying out any work on the system.

In this regard, refer to the instructions in the currentService Literature.



Tick the correct answer or fill in the gaps.

1. What is the advantage of the common rail system?

a. The high injection pressures reduce combustion temperatures; exhaust gas recirculation is not required.

b. Pressure generation and injection are separated.

c. The injection pressure is generated as a function of engine speed.

d. Combustion noise is substantially reduced as a result of indirect injection.

2. What is the effect of pilot injection?

a. Pilot injection results in an abrupt build-up of combustion pressure and therefore reduced combustion noise.

b. Pilot injection results in an abrupt build-up of combustion pressure and therefore increased combustionnoise.

c. Pilot injection results in a gradual increase in combustion pressure.

d. Pilot injection only results in a reduction of fuel consumption.

3. Where are post-injections utilised?

a. In vehicles with an electric EGR system.

b. In vehicles with an NOX catalytic converter.

c. In vehicles without a diesel particulate filter system.

d. In vehicles with a diesel particulate filter system.

4. The overtorque function

a. prevents abrupt deceleration when the accelerator pedal is suddenly released at high vehicle speeds.

b. makes it possible to briefly exceed the maximum specified torque when starting the vehicle on a gradient.

c. makes it possible to briefly exceed the maximum specified torque during rapid acceleration.

d. is activated in response to certain malfunctions in the engine management system.


Lesson 1 – General InformationTest questions

Overview

Bosch common rail system with "solenoid valve-controlled" fuel injectors

E51106

7

6

G

A

B

CD

E

F

5

12

3

4

8

Fuel lineA

Run-off line for excess delivered fuelB

High-pressure lineC

Fuel injection lineD

Fuel return from the fuel pumpE

Leak-off pipeF

Fuel return to the fuel tankG

Fuel pump1

Fuel rail (common rail)2

Fuel injector3

Fuel temperature sensor4

Fuel return collector pipe5


Lesson 2 – Fuel System

Fuel filter6 Fuel tank7

Fuel pump and sender unit8

Bosch common rail system with "piezo-controlled" fuel injectors

E96088

12

4

5

8

6

B

A

F

E

7

C

D

3

Fuel return from the fuel pumpA

High-pressure lineB

Fuel injection lineC

Leak-off pipeD

Fuel return to the fuel tankE

Fuel lineF

Fuel pump1

Fuel rail2

Fuel injector3

Back pressure valve4



Return gateway5

Fuel tank6


Fuel filter8


E53588

78

6

4

F

A

BC

D

E

12

3

5

Fuel lineA

High-pressure lineB


Fuel return from the fuel pumpD

Leak-off pipeE

Fuel return to the fuel tankF

Fuel pump1


Fuel injector3

Fuel return collector pipe4




Fuel filter6

Fuel tank7



E69808

1 2

34

5

8

6

B

A

F

E

7

C

D

Fuel return from the fuel pumpA

High-pressure lineB


Leak-off pipeD

Fuel return to the fuel tankE

Fuel lineF

Fuel pump1


Fuel injector3

Pressure relief valve4



T-piece5

Fuel tank6


Fuel filter8



General

Function

Fuel is drawn from the fuel tank through the fuel filterby the transfer pump which is integrated in the fuelpump.

The fuel pump compresses the fuel and forces it intothe fuel rail.

The fuel pressure required for any given situation isavailable for the fuel injectors for each injection process.

Leak-off fuel from the fuel injectors and/or returningfuel from the fuel pump is fed back into the fuel tank.

Possible causes of faults in fuel lines and the fueltank

Fuel lines may be blocked due to foreign bodies orbending.

In addition, blocked parts and lines of the low-pressuresystem can cause air to get into the low-pressure systemon account of the increased vacuum in the system.

Air can also enter the low-pressure system through looseor leaking line connections.

Faulty valves or lines in the tank ventilation system canimpair the flow of fuel through the low-pressure system.

Effects of faults (low-pressure system containsair or is blocked)

Poor engine starting when warm or cold.

Irregular idling.

Engine will not start.

Engine starts, but cuts out again immediately afterwards.

Engine has insufficient power.

Note: At a certain residual fuel amount, the PCM causesthe engine to judder. The intention is to draw the driver'sattention to the fact that the vehicle must urgently berefuelled.

Note for vehicles with EOBD: If the PCM causes theengine to judder because the fuel tank is empty, theEOBD (European On-Board Diagnostics) aredeactivated during this phase. This prevents apparentfaults from being displayed.


Lesson 2 – Fuel SystemLow-pressure system

Fuel filter

System with solenoid valve-controlled fuelinjectors

E43249

1

4

3

2

Fuel line to the fuel pump1

Water drain screw2

Electric fuel preheater3

Fuel line connection with fuel tank4

The fuel filter clipped onto the transaxle end of thecylinder head is equipped with an electric fuel heater.

There is a water drain screw in the top section of thefilter housing for draining the filter.

The fuel filter must be drained of water regularly inaccordance with the service intervals.

E51107

1

2 5

6

1

15 30

3

2

43

2

1

5

7

6

Battery junction box1

Fuel preheater relay2

Fuse (10A)3

Fuse (15A)4

Ground5

Electric fuel preheater in the fuel filter6

Ground7

The electric bimetallically-controlled fuel preheaterworks independently of the PCM.

It is actuated via a fuel preheater relay when the ignitionis switched on (ignition ON). However, the activationof the heating element is dependent on the currenttemperature.

Below a fuel temperature of 0 to –4 °C, the circuit isclosed by the bimetal and the heating element thusenergised.

The bimetal opens the circuit at a fuel temperature from1 to 5 °C and ends the heating phase.


Bosch common rail systemLesson 2 – Fuel System

System with piezo-controlled fuel injectors

132

4

5

6

7

132

4

5

6

7

E97401

Fuel return (to the fuel tank)1

Fuel return line (from the fuel pump)2


Fuel line (to the fuel pump)4

Fuel filter water drain screw5

Water drain line6

Fuel line (from the fuel tank)7

The fuel filter is made of plastic. It is installed on thefront side of the engine on the intake side. A securityshield protects the fuel filter from damage in the eventof a frontal impact.

Located on the fuel filter housing is a water drain screw.The fuel filter must be drained via this screw inaccordance with the service intervals.

Note:

• Before draining the fuel filter, make sure that thesurrounding components do not come into contactwith the fuel that is drained.

There is a thermo valve integrated in the fuel filter forpreheating the fuel.


Lesson 2 – Fuel SystemBosch common rail system

How fuel preheating works

1

234

5

6 7

A B

1

234

5

6 7

A B

E96134

Fuel return temperature < 10 °CA

Fuel return temperature > 20 °CB

Fuel return line (to the fuel tank)1

Fuel return outlet2

Bypass (to the fuel filter)3

Upper part of the fuel filter4

Fuel return line (from the fuel pump)5

Thermostat open6

Thermostat closed7

The fuel filter is equipped with a mechanical fuelpreheater.

There is a spring-loaded thermo valve integrated in thefuel return in the upper part of the fuel filter. The thermovalve determines the quantity of fuel that is returned tothe fuel tank or flows directly back into the fuel filter.

Fuel return temperature < 10 °C:

• The thermo valve is in compressed state.

• The bypass to the fuel filter is wide open in this state.The cross section of the fuel return outlet is slightlyopen.

• The majority of the returning fuel flows through thewide open bypass into the fuel filter. Only a smallpart of the returning fuel can flow back to the fueltank via the slightly open cross section of the fuelreturn outlet.



Fuel return temperature > 20 °C:

• The thermo valve expands against the spring force.

• The bypass to the fuel filter is only slightly open inthis state. The cross section of the fuel return outletis now wide open.

• The majority of the returning fuel flows through thewide open fuel return outlet. Only a small part of thereturning fuel can flow through the slightly openbypass to the fuel filter.

Percentage of fuel to the fuel filterPercentage of fuel to the fuel tankFuel return temperature

90 - 95 %5 - 10 %< 10 °C

0 - 5 %95 - 100 %> 20 °CPossible causes of faults

Fuel filters may be blocked by dirt. Air may also enterthe low-pressure system as a result of leaks in the fuelfilter.

Effects of faults

Poor starting when the engine is warm or cold.

Irregular idling.






Overview of the high-pressure system

System with "solenoid valve-controlled" fuel injectors

E51108

3

4

5

6

789

1

2

Fuel injector1

Fuel injection line2

Leak-off pipe3

Fuel metering valve4

Transfer pump5

High-pressure line6

Fuel pump7


Fuel pressure sensor9



System with "piezo-controlled" fuel injectors

2 3 4 5 6

7

8

9

10

1

11

2 3 4 5 6

7

8

9

10

1

11

E97421

Fuel injector1




High-pressure line5

Overpressure leakage line6

Fuel pressure control valve7

Fuel return8

Fuel pump9

Fuel line10

Set of leak-off pipes with back pressure valve *11

* There is a back pressure valve in the set of leak-offpipes. This valve maintains a back pressure of approx.10 bar in the leak-off pipe while the engine is running.The back pressure valve cannot be renewed separatelyduring servicing.



Fuel pump

Overview

CP3.2 fuel pump

E51109

1

2 3 4 5

6

Transfer pump1


Pump plunger3

Eccentric4

Halfshaft5

Pump housing6



CP1H fuel pump

E70770

2

3

4

5

1


Fuel return connection2

Fuel line connection3

Transfer pump4

High-pressure connection (to the fuel rail)5

Two different types of fuel pump are used in the Boschcommon rail system:

• CP3.2 fuel pump and

• CP1H fuel pump.

With the launch of the Focus C-MAX 2003.75(06/2003-), initially only the CP3.2 was installed. Overtime, the CP3.2 was increasingly replaced by the CP1Hand this pump was installed from the outset for newlaunches.

The following table shows the introduction dates forthe CP1H based on the vehicle.

Introduction of CP1HVehicle

October 2004Fiesta 2002.25 (11/2001-)

February 2005Focus C-MAX 2003.75(06/2003-)/Focus 2004.75(07/2004-) with 67 kW (90PS)

May 2005Focus C-MAX 2003.75(06/2003-)/Focus 2004.75(07/2004-) with 82 kW(110 PS)

With the start of produc-tion

Mondeo 2007.5/S-MAX/Galaxy 2006.5

The function of the CP1H fuel pump is essentially thesame as that of the CP3.2.



Flow of fuel through the fuel pump

E51111

5

42

6

E

D

C3

B

F

A

1

7 8

9

G

To the fuel injectorsA

High fuel pressureB

Flow of fuel through the fuel pumpC

Return flow to the transfer pumpD

Fuel lineE

Fuel injector leak-offF

Fuel returnG

Fuel rail1

High-pressure part2

Pressure restrictor3


Overflow throttle valve5

Fuel pump6

Transfer pump7

Fuel filter8

Fuel tank9



Transfer pump

E51110

2

31

Intake side1

Drive gear2

Delivery side3

The transfer pump is designed as a gear pump anddelivers the required fuel to the fuel pump.

Essential components are two counter-rotating, meshedgears that transport the fuel in the tooth gaps from theintake side to the delivery side.

The contact line of the gears forms a seal between theintake side and the delivery side and prevents the fuelfrom flowing back.

The delivery quantity is approximately proportional tothe engine speed. For this reason, fuel quantity controlis required.

There is an overflow throttle valve incorporated in thefuel pump for fuel quantity control purposes.

Overflow throttle valve

E51112

6 6 6

3 3 3

4

4

8

7 7 7

9

5

CBA

5 5

1

2

1

2

1

2

4

8

Low engine speedsA

Increasing engine speedsB

High engine speedsC

Transfer pump pressure1

Time2

Compression spring3

Restrictor4

To the high-pressure chambers5



Control piston6

Fuel pump lubrication/cooling/ventilation7

Fuel pump cooling bypass8

Return bypass to the transfer pump9

High-pressure generation (up to 1,800 bar) means highthermal load on the individual components of the fuelpump. The mechanical components of the fuel pumpmust also be sufficiently lubricated to ensure durability.

The overflow throttle valve is designed to ensureoptimum lubrication or cooling for all operatingconditions.

At low engine speeds (low transfer pump pressure), thecontrol piston is moved only slightly out of its seat. Thelubrication/cooling requirement is correspondingly low.

A small amount of fuel is released to lubricate/cool thepump via the restrictor at the end of the control piston.

NOTE: The fuel pump features automatic venting. Anyair present in the fuel pump is vented through therestrictor.

With increasing engine speed (increasing transfer pumppressure), the control piston is moved further againstthe compression spring.

Increasing engine speeds require increased cooling ofthe fuel pump. Above a certain pressure, the fuel pumpcooling bypass is opened and the flow rate through thefuel pump is increased.

At high engine speeds (high transfer pump pressure),the control piston is moved further against thecompression spring. The fuel pump cooling bypass isnow fully open (maximum cooling).

Excess fuel is transferred to the intake side of thetransfer pump via the return bypass.

In this way, the internal pump pressure is limited to amaximum of 6 bar.

High-pressure generation

E51113

9

8

7

3

2

1

4

6 5



High pressure to the fuel rail1

Exhaust valve2

Spring3

Fuel line4

Halfshaft5

Eccentric cam6

High-pressure chamber7

Pump plunger8

Intake valve9

The fuel pump is driven via the halfshaft. An eccentricelement is fixed to the halfshaft and moves the threeplungers up and down according to the shape of thecams on the eccentric element.

Fuel pressure from the transfer pump is applied to theintake valve. If the transfer pressure exceeds the internalpressure of the high-pressure chamber (pump plungerin TDC position), the intake valve opens.

Fuel is now forced into the high-pressure chamber,which moves the pump plunger downwards (intakestroke).

If the BDC position of the pump plunger is exceeded,the intake valve closes due to the increasing pressure inthe high-pressure chamber. The fuel in the high-pressurechamber can no longer escape.

As soon as the pressure in the high-pressure chamberexceeds the pressure in the fuel rail, the outlet valveopens and the fuel is forced into the fuel rail via thehigh-pressure connection (delivery stroke).

The pump plunger delivers fuel until TDC is reached.The pressure then drops so that the outlet valve closes.

As the pressure on the remaining fuel is reduced, thepump plunger moves downward.

If the pressure in the high-pressure chamber falls belowthe transfer pressure, the intake valve reopens and theprocess starts again.

Zero delivery valve

E511142 3

14

From the high-pressure chamber annular channel1

Zero delivery valve2

Calibrated bore (ø = 0.4 mm)3

To the transfer pump4

The zero delivery valve is located between the annularchannel that is connected to the intake valves of thehigh-pressure chambers and the fuel metering valve.

Even in the fully closed state, the fuel metering valve(see "Lesson 3 – Engine management system") is notcompletely sealed. In other words, a small amount ofleakage still gets into the annular channel to thehigh-pressure chambers due to the transfer pumppressure. As a result, the intake valves are opened andan undesirable pressure increase may occur in thehigh-pressure system.

To prevent this, the zero delivery valve features acalibrated bore. In this way, excess fuel is fed back tothe intake side of the transfer pump.



Fuel rail (common rail)

Structure and purpose

E43248

1


The fuel rail is made of forged steel.

The fuel rail performs the following functions:

• stores fuel under high pressure and

• minimises pressure fluctuations.

Pressure fluctuations are induced in the high-pressurefuel system due to the operating movements in thehigh-pressure chambers of the fuel pump and theopening and closing of the solenoid valves on the fuelinjectors.

Consequently, the fuel rail is designed in such a waythat, on the one hand, it possesses sufficient volume tominimise pressure fluctuations, but, on the other hand,the volume in the fuel rail is sufficiently low to buildup the fuel pressure required for a quick start in theshortest possible time.

Function

The fuel supplied by the fuel pump passes through ahigh-pressure line to the high-pressure accumulator.The fuel is then sent to the individual fuel injectors viathe four fuel injection lines which are all the samelength.

When fuel is taken from the fuel rail for an injectionprocess, the pressure in the fuel rail remains almostconstant.

Fuel pressure sensor

There is a fuel pressure sensor located on the fuel railso that the engine management system can preciselydetermine the injected fuel quantity as a function of thecurrent fuel pressure in the fuel rail (see "Lesson 4 –Sensors").

High-pressure fuel lines

E43246

NOTE: The bending radii are exactly matched to thesystem and must not be changed.

NOTE: After disconnecting one or more high-pressurefuel lines, these must always be renewed. The reasonfor this is that leaks can occur when retightening due todistortion of the connections of the old lines.

The high-pressure fuel lines connect the fuel pump tothe fuel rail and the fuel rail to the individual fuelinjectors.

Fuel injectors (general)

Depending on the engine type, different fuel injectorsare used:

• solenoid valve-controlled fuel injectors or

• piezo-controlled fuel injectors.

Solenoid valve-controlled fuel injectors are installedin the 1.6L Duratorq-TDCi (DV) diesel engine.

Piezo-controlled fuel injectors are installed in the 2.2LDuratorq-TDCi (DW) diesel engine.

Start of injection and injected fuel quantity arecontrolled via the fuel injectors.



The injection timing is calculated using the angle/timesystem in the PCM. The main input variables for thisare the signals from the CKP and the CMP (CamshaftPosition) sensors.

Solenoid valve-controlled fuel injectors

E43245

3

4

2

5

1

7

6

Leak-off pipe connection1

Retainer2

Plastic ring3

Seal4

Combustion chamber seal5

High-pressure fuel line connection6

Solenoid valve connector7

NOTE: The combustion chamber seals must not bereused. The exact procedure for the correct installationof the seals and the plastic rings can be found in thecurrent Service Literature.

The fuel injectors are divided into different functionblocks:

• injector nozzle,

• hydraulic servo system,

• solenoid valve.



Function

E51115

BA

11

12 13

9

8

7

6

10

11

1

2

9

8

7

6

5

4

310

Fuel injector closedA

Fuel injector openB

Solenoid valve coil1

Feed channel2

Valve ball3

Feed restrictor4

Feed channel to the nozzle prechamber5

Nozzle needle6

Nozzle prechamber7

Nozzle needle spring8

Valve control piston9

Valve control chamber10

Outlet restrictor11



Fuel return12 Solenoid valve connector13

The fuel is fed from the high-pressure connection via afeed channel into the nozzle prechamber and via thefeed restrictor into the valve control chamber.

The valve control chamber is connected to the fuel returnvia the outlet restrictor, which can be opened by meansof a solenoid valve.

Fuel injector closed

In its closed state (solenoid valve de-energised), theoutlet restrictor is closed by the valve ball so that nofuel can escape from the valve control chamber.

In this state, the pressures in the nozzle prechamber andin the valve control chamber are the same (pressurebalance).

There is, however, also a spring force acting on thenozzle needle spring so that the nozzle needle remainsclosed (hydraulic pressure and spring force of the nozzleneedle spring). No fuel can enter the combustionchamber.

Fuel injector opens

The outlet restrictor is opened via actuation of thesolenoid valve. This lowers the pressure in the valvecontrol chamber, as well as the hydraulic force on thevalve control piston.

As soon as the hydraulic force in the valve controlchamber falls below that of the nozzle prechamber andthe nozzle needle spring, the nozzle needle opens. Fuelis now injected into the combustion chamber via thespray holes.

Fuel injector closes

After a period determined by the PCM, the power supplyto the solenoid valve is interrupted.

This results in the outlet restrictor being closed again.By closing the outlet restrictor, pressure from the fuelrail builds up in the valve control chamber via the feedrestrictor.

This increased pressure exerts an increased force on thevalve control piston. This force and the spring force ofthe nozzle needle spring now exceed the force in thenozzle prechamber and the nozzle needle closes.

Note: The closing speed of the nozzle needle isdetermined by the flow rate at the feed restrictor.Injection terminates when the nozzle needle reaches itsbottom stop.

Indirect actuation

Indirect actuation of the nozzle needle via a hydraulicbooster system is used because the forces required forrapid opening of the nozzle needle cannot be generateddirectly with the solenoid valve.

The "control quantity" therefore required in addition tothe injected fuel quantity enters the fuel return via therestrictors in the control chamber.

Leak-off quantities

In addition to the control quantity, there are leak-offquantities at the nozzle needle and valve control pistonguides.

These leak-off quantities are also discharged into thefuel return.

Service instructions (fuel injector correctionfactor)

E51116

0115440 136

080F DDFO

760680

3841501517242809

12

Fuel injector1

Correction factor2

Inside the hydraulic servo system there are variousrestrictors with extremely small diameters which havespecific manufacturing tolerances.

These manufacturing tolerances are given as part of acorrection factor which is located on the outside of thefuel injector.



To ensure optimum fuel metering, the PCM must beinformed when a fuel injector is changed.

Furthermore, after new PCM software has been loadedvia the IDS (Integrated Diagnostic System), the fuelinjectors must also be configured with this software.

This is done by inputting the 8-digit correction factor(divided into two blocks of four on the fuel injector)into the PCM with the help of the IDS and taking intoaccount the corresponding cylinder.

Note: If the correction factors are not entered properlywith the IDS, the following faults can occur:

• increased black smoke formation,

• irregular idling,

• increased combustion noise,

• engine will not start.

Effects of faulty fuel injector(s) (mechanicalfaults)

Increased black smoke production.

Fuel injector leaks.

Increased combustion noise as a result of coked nozzleneedles.

Irregular idling.

Piezo-controlled fuel injectors

1

2

3

4

6

5

1

2

3

4

6

5

E96132

Fuel injector retaining bolt1

Retaining clip centring pin2

Seal3

Centring ring4

Fuel injector5

Retaining clip6



The fuel injectors are mounted on the cylinder head andprotrude into the centre of the individual combustionchambers.

The fuel injectors are opened and closed using a piezoelement. The piezo element is located inside the fuelinjector.

The piezo-controlled fuel injectors switch around fourtimes faster than solenoid valve-controlled fuelinjectors.

The results in the following advantages:

• Multiple injections with flexible injection timing andintervals between the individual injections.

• Realisation of very small injected fuel quantities forthe pilot injection(s).

• Low noise emissions (up to 3 dB).

• Improved fuel economy (up to 3%).

• Lower exhaust emissions (up to 20%).

• Increased engine power output (up to 7%).

• Improved running smoothness.

Function

Structure of the piezo-controlled fuel injector

E97388

1

2

3

4

5

6

a b

Fuel returna

High-pressure connectionb

Piezo element1

Hydraulic coupler2

Control valve3

Nozzle module with nozzle needle4

Spray holes5

Electrical connector6

In the case of the piezo-controlled fuel injector, thenozzle needle is indirectly controlled via a control valve.

'Indirectly' means that the nozzle needle is opened andclosed via a hydraulic circuit.

The hydraulic circuit comprises a low-pressure and ahigh-pressure part. The control valve provides theinterface between the high-pressure and the low-pressureparts.

The required injected fuel quantity is controlled via theopening times of the control valve.



Function of the control valve

a b c

A B C

1

2

4

3

5

6

a b c

A B C

1

2

4

3

5

6

E97392

Initial positionA

Nozzle needle opensB

Nozzle needle closesC

Control valve1

Outlet restrictor2

Control chamber3

Feed restrictor4

Nozzle needle5

Bypass6

Fuel rail pressurea

Leak-off pressureb

Control chamber pressurec

Initial position

• If the piezo element is not activated by the PCM,then the control valve is in the initial position. Thismeans that the high-pressure part is closed off fromthe low-pressure part.

• The fuel rail pressure plus the spring force is actingupon the nozzle needle. The fuel injector nozzle isclosed (no injection).

Nozzle needle opens

• When the piezo element is activated, the controlvalve opens and closes the bypass.

• The pressure in the control chamber can then escapeinto the fuel return.

• The pressure in the control chamber is reduced viathe flow rate ratio of the outlet and feed restrictors.

• The fuel rail pressure on the nozzle needle is nowgreater than the pressure in the control chamber andthe spring force. The nozzle needle is lifted andinjection begins.



Nozzle needle closes

• When the piezo element is discharged by the PCM,the control valve opens the bypass once more.

• The control chamber is then filled again via the feedand outlet restrictors. The control chamber pressureincreases again rapidly via the bypass.

• As soon as the control chamber pressure plus thespring force are once more greater than the fuel railpressure on the nozzle needle, the nozzle needlecloses and injection ends.

Hydraulic coupler

1

3

2

4

6

5

1

3

2

4

6

5

E97396

Piezo element1

Back pressure valve2

Hydraulic coupler back pressure3

Hydraulic coupler4

Control valve piston5

Piezo element piston6

The hydraulic coupler fulfils the following functions:

• Transmission and amplification of the piezo stroke.

• Compensation of any play.

• Termination of injection in the event of electricaldisconnection of the fuel injector (e.g. if a cablebreaks during the injection process).

The hydraulic coupler is comparable to a hydraulic lashadjuster in terms of its function.

The fuel around the hydraulic coupler has a backpressure of approx. 10 bar. The back pressure valve islocated in the leak-off pipe.

Piezo element not actuated:

• In this state, the pressure in the hydraulic coupler isin balance with its surroundings (around 10 bar).

Piezo element actuated:

• The piezo element piston moves downwards. As aresult, the pressure in the hydraulic coupler rises. Asmall amount of leakage flows from the hydrauliccoupler into the low-pressure circuit of the fuelinjector via the piston guide clearances.

• The pressure increase in the hydraulic coupler causesdownward movement of the control valve piston viathe hydraulic cushion and injection starts.

Once the injection process is finished, the deficit in thecoupler must be refilled. This is done in reverse via theguide clearances of the piston.

The back pressure of around 10 bar is extremelyimportant for the correct operation of the fuel injectors.

Service instructions (fuel injector correctionfactor)

E96133

Inside the hydraulic servo system there are calibratedbores with extremely small diameters. These bores havespecific manufacturing tolerances. Tolerances also arisewhen the mechanical, hydraulic and electricalcomponents are combined.

At the factory, each fuel injector is tested and then sortedinto a specific category. The fuel injector is assigned acorrection factor according to the category.

The 10-digit correction factor is engraved on the headof the fuel injector (arrow).



To ensure precise fuel metering, the PCM must beinformed when an injector is changed.

The correction factor is entered with the help of the IDS.When entering the number, make sure that the fuelinjector is assigned to the correct cylinder.

Effects of faults

Fuel injector(s) (mechanical faults):

• increased black smoke production,

• fuel injector leaks,

• increased combustion noise as a result of cokednozzle needles.



Fuel filter

Function

Fuel filter of the 1.4L Duratorq-TDCi (DV) diesel engine

E53589

1

2

3

5

4

Fuel line connection (from the fuel tank)1

Fuel line connection (to the fuel pump)2

Fuel filter with water separator3

Water drain screw4


Different fuel filters are used for the Siemens commonrail system depending on the type of engine. Theiroperating principles and service-relevant characteristics,however, are very similar.

Both fuel filters are equipped with a water separatorwhich must be drained regularly in accordance with thespecified service intervals.

Both fuel filters also feature a fuel preheater which isactivated at low temperatures.

Fuel filter of the 2.0L Duratorq-TDCi (DW) diesel engine

E43236

1 2

3

4

Fuel line connection (from the fuel tank)1

Fuel feed connection (to the fuel pump)2


Water drain screw4

The fuel preheater is bimetallically-controlled andfunctions independently of the PCM.

The bimetallically-controlled fuel preheater is activatedwhen the ignition is on (ignition key in position II)regardless of whether the engine is running or not.

The bimetal closes the circuit as a function of theambient temperature and the heating element in the fuelpreheater is activated.

• For the 1.4L Duratorq-TDCi, the on/off temperaturefor the heating element is approximately 5 °C.

• For the 2.0L Duratorq-TDCi (DW) diesel engine,the heating element is switched on at –2 °C ± 2 °Cand switched off at +3 °C ± 2 °C.

Possible causes of faults

Fuel filters may be blocked by dirt. Air may also enterthe low-pressure system as a result of leaks in the fuelfilter.

Note: A certain quantity of air is drawn out of the fueltank together with the fuel when the transfer pump drawsfuel into the fuel pump. The air bubbles are very small,however, and cannot initially be seen with the nakedeye.

The small air bubbles are separated out in the fuel filterand clump together to form larger bubbles. These airbubbles occasionally emerge from the filter material


Lesson 2 – Fuel SystemSiemens common rail system

and are drawn into the fuel pump. They can be seenthrough a transparent hose. This form of separation isentirely normal.

The visual inspection for air bubbles in the transparenthose is therefore not counted as a fault diagnosis.

Effects of faults

Poor starting when the engine is warm or cold.

Irregular idling.





Illustration shows the high-pressure system of the 2.0L Duratorq-TDCi (DW) diesel engine

E43283

1

2

34

56

Fuel injector1



Fuel pump4

Fuel rail5



Siemens common rail systemLesson 2 – Fuel System

Fuel pump

Overview

Illustration shows the fuel pump with halfshaft for timing belt drive (1.4L Duratorq-TDCi (DV) diesel engine)

E53590

1

5

6

23

A

B

C

4

Fuel returnA

High-pressure connectionB

Fuel lineC

Fuel metering valve (partial view)1

High-pressure pump element (displacement unit)2


Eccentric4

Halfshaft5

Transfer pump6

NOTE: The fuel metering valve as well as the fuelpressure control valve are part of the fuel pump andtherefore must not be renewed separately duringservicing.

Note: Depending on the engine version, the fuel pumpis driven via the timing belt for camshaft drive (1.4LDuratorq-TDCi (DV) diesel engine) or via the exhaustcamshaft (2.0L Duratorq-TDCi (DW) diesel engine).The design and function of the fuel pump are essentiallysimilar.



High-pressure generation and fuel routing in the fuel pump

E53591

1

10

13

14

11

9

10

10

11

11

12

1313

4

B

D

8

A

C3

2

5

7 6

Fuel lineA

Fuel line (fuel quantity fed to the fuel pump)B

High-pressure connection to the fuel railC

Fuel returnD

Admission-pressure control valve1

Strainer filter2

Intake side of the transfer pump3

Transfer pump4



Filter7

Fuel pump8

Eccentric on the halfshaft9

Pump element intake valve10



Pump element outlet valve11

High-pressure ring line12

High-pressure pump elements13

Lubrication valve14

The fuel is drawn from the fuel tank via the fuel filterby means of the transfer pump integrated in the fuelpump.

The transfer pump delivers the fuel on to the fuelmetering valve and to the lubrication valve. When thefuel metering valve is closed, the admission pressurecontrol valve opens and routes the excess fuel back tothe intake side of the transfer pump.

The lubrication valve is calibrated to always ensuresufficient lubrication and cooling in the interior of thepump.

The fuel quantity fed to the high-pressure chambers(pump elements) is determined via theelectromagnetically-operated fuel metering valve(actuated by the PCM).

The high-pressure chambers are formed by three pumpelements (displacement units), each offset by 120degrees.

The fuel pressure control valve is located in thehigh-pressure channel, between the high-pressurechambers and the high-pressure outlet port to the fuelrail. This electromagnetically-operated valve which isactuated by the PCM controls the fuel pressure whichis fed into the fuel rail via the high-pressure outlet port.

The fuel pressure control valve routes the excess fuelinto the fuel return line and back to the fuel tank.

Principle of high-pressure generation (intake stroke)

E53592

1

1

5

4

3

2

A B

C2

3

4

5

D

Fuel intakeA

Fuel deliveryB

Fuel feed from the fuel metering valveC

Fuel outlet port to the high-pressure ring lineD

Intake valve1

Exhaust valve2

Piston3

Halfshaft4

Eccentric5

The three pump plungers are actuated by the rotarymovement of the fuel pump halfshaft and the eccentricon the shaft.

When the fuel metering valve opens the feed to thehigh-pressure chambers, the fuel pressure from thetransfer pump is fed to the intake valves at the



high-pressure chambers. If the transfer pressure exceedsthe internal pressure of the high-pressure chamber (pumpplunger in TDC position), the intake valve opens.

Fuel is now forced into the high-pressure chamber,which moves the pump plunger downwards (intakestroke).

Principle of high-pressure generation (deliverystroke)

When the pump plunger passes BDC, the intake valvecloses due to the increasing pressure in the high-pressurechamber. The fuel in the high-pressure chamber can nolonger escape.

As soon as the pressure in the high-pressure chamberexceeds the pressure in the high-pressure channel, theexhaust valve opens and the fuel is forced into thehigh-pressure channel (delivery stroke).

The pump plunger delivers fuel until TDC is reached.The pressure then drops and the exhaust valve closes.

The pressure on the remaining fuel is reduced. The pumpplunger moves downwards.

If the pressure in the high-pressure chamber falls belowthe transfer pressure, the intake valve reopens and theprocess starts again.

Service instructions

Specific versions only:

After installing a new fuel pump, the adapted valuesof the fuel metering valve must be reset with the helpof the IDS.

Fuel rail and high-pressure fuel lines

Fuel rail

Illustration shows the system in the 2.0L Duratorq-TDCi(DW) diesel engine

E53593

2

34

1

High pressure fuel lines (to the fuel injectors)1

High-pressure fuel line (to the fuel pump)2

Fuel rail3


The fuel rail is made of forged steel.




Pressure fluctuations are induced in the high-pressurefuel system due to the operating movements in thehigh-pressure chambers of the fuel pump and theopening and closing of the fuel injectors.

The fuel rail is therefore designed in such a way that itsvolume is sufficient, on the one hand, to minimisepressure fluctuations. On the other hand, the volumein the fuel rail is sufficiently low to build up the fuelpressure required for a quick start in the shortestpossible time.

The fuel supplied by the fuel pump flows via ahigh-pressure line to the fuel rail (high-pressureaccumulator). The fuel is then sent to the individual fuelinjectors via the four fuel injection lines which are allthe same length.





NOTE: The fuel pressure sensor must not be removedfrom the fuel rail during servicing. If the fuel pressuresensor is faulty, the fuel rail must be renewed along withthe fuel pressure sensor.

There is a fuel pressure sensor located on the fuel railso that the engine management system can preciselydetermine the injected fuel quantity as a function of thecurrent fuel pressure in the fuel rail (see also "Lesson 4- Sensors").





Fuel injectors

E53594

1

7

6

89

104

11

6

7

23

1

E

D

C

2

3

4

5

6

A B

E

D

C

Fuel injector (1.4L Duratorq-TDCi (DV) dieselengine and 1.8L Duratorq-TDCi (Kent) dieselengine)

A

Fuel injector (2.0L Duratorq-TDCi (DW) dieselengine)

B

Fuel injector headC

Hydraulic servo systemD

Fuel injector nozzleE

Connector for PCM1

Piezo actuator2

High-pressure fuel line connection3




Emission standard coding5

Fuel return connection6

Retainer7

Fuel return adapter8

O-ring9

Adapter fastening clip10

Plastic bush11

Depending on the engine version, fuel injectors ofdifferent designs are used. Their basic construction andfunction are, however, largely the same.

The start of injection and the injected fuel quantityspecified by the PCM are implemented by means of thepiezo-electrically-controlled fuel injectors.

Depending on engine speed and engine load, the fuelinjectors are actuated by the PCM with an openingvoltage of approximately 70 V. The piezo effect causesthe voltage within the piezo element to rise toapproximately 140 V.

The fuel injectors inject the appropriate fuel quantityper working cycle for all engine operating conditionsinto the combustion chambers.

Extremely short switching times of approximately 200µs permit extremely rapid reaction to changes in theoperating conditions. The fuel quantity to be injectedcan thus be metered very precisely.

The fuel injectors are divided into three assemblies:

• fuel injector head, including the piezo actuator,


• fuel injector nozzle.

NOTE: The fuel injectors cannot be dismantled duringrepair as this results in their destruction.

NOTE: The wiring harness connectors of the fuelinjectors must on no account be unplugged when theengine is running. The piezo actuators remain expandedfor a certain period after the power is cut off in thecharging phase, i.e. the nozzles remain open. Effect:continuous injection and engine damage.

The combustion chamber seals must be renewed duringservicing.

Special features

1.4L Duratorq-TDCi (DV) diesel engine:

• In newer versions, a distinction is made betweenEmission Standard III and Emission Standard IVfuel injectors. A code is stamped onto the fuelinjector shaft for this purpose:

– E3 = Emission Standard III,

– E4 = Emission Standard IV.

2.0L Duratorq-TDCi (DW) diesel engine:

• A guide bushing located in the lower part of thecylinder head and a plastic bushing on the fuelinjector shaft serve to fasten the fuel injector.



How fuel injectors work

Fuel injector closed

E53595

4

3

2

1

8

2

6

3 35

7

High-pressure feed1

Control piston2

Fuel return3

Piezo actuator4

Mushroom valve5

Control chamber6

Nozzle prechamber7

Nozzle needle8

The fuel is fed at high pressure from the fuel rail via thehigh-pressure feed into the control chamber and thenozzle prechamber.

The piezo actuator is de-energised and the orifice to thefuel return is closed by means of the spring-loadedmushroom valve.

The hydraulic force now exerted on the nozzle needleby the high fuel pressure in the control chamber via thecontrol piston is greater than the hydraulic force actingon the nozzle needle, as the surface of the control pistonin the control chamber is greater than the surface of thenozzle needle in the nozzle prechamber.

The nozzle needle of the fuel injector is closed (noinjection).



Fuel injector opens

E53596

3

6

2

8

1

4

3

2

7

9

5

9

High-pressure feed1

Control piston2

Fuel return3

Piezo actuator4

Mushroom valve5

Control chamber6

Nozzle prechamber7

Nozzle needle8

Valve piston9

The piezo actuator which is energised by the PCMexpands (charging phase) and pushes against the valvepiston.

The mushroom valve opens the orifice which connectsthe control chamber with the fuel return.

This results in a pressure drop in the control chamberand the hydraulic force acting on the nozzle needle isnow greater than the force acting on the control pistonin the control chamber.

This causes the nozzle needle to be moved upwards, thefuel injector opens and the fuel enters the combustionchamber via the spray holes.

The piezo actuator is deactivated at a certain pointdetermined by the PCM. The valve piston moves backupwards and the mushroom valve closes off the controlchamber.

As soon as the pressure in the control chamber exceedsthe pressure in the nozzle prechamber, the nozzle needlecloses off the spray holes and injection ends.



Fuel injector identification markings

E53597fedc

b

a

Identification number coding:

a. Classification (2.0L Duratorq-TDCi (DW) dieselengine only)

b. Ford part number

c. Year of manufacture (C = 2003, D = 2004 . . . )

d. Month (A = January, B = February, . . . L =December)

e. Day (01 ... 31)

f. Part number (00001 ... 99999)

The identification markings of the piezo fuel injectorsare located on the fuel injector head.

Classification (correction factor):

• The fuel injectors of the 2.0L Duratorq-TDCi(DW) diesel engine are marked with a number forclassification purposes.

• A total of three classifications are available:

– 4, 5 and 6

• When installing one new fuel injector, it should benoted which classification is marked on the fuelinjector.

• All the fuel injectors installed in an engine must havethe same classification.

When installing all new fuel injectors, the new fuelinjectors may have a different classification, Forexample, if the old fuel injectors are in class "5" and thenew ones are all class "4", this is permissible.

The change of classification must nevertheless becommunicated to the PCM with the help of the IDS.





Irregular idling.



Fuel filter

How fuel preheating works

E69908

2

3

4

5

6

8

7

1

Fuel return (to the fuel filter)1

Fuel return (to the fuel tank)2

Fuel line (to the fuel pump)3

Fuel filter minder gauge4

Water-in-fuel sensor (certain markets only)5

Water drain screw6

Water-in-fuel sensor wiring harness7

Fuel line (from the fuel tank)8

Fuel preheating works via a bimetallically-controlledcontrol valve. Fuel flow control only works at fueltemperatures between 15 and 45 ° C.

Fuel temperature below 15 °C:

• The bimetallically-controlled control valve is fullyopen; a defined fuel return volume from the fuelpump is returned directly to the fuel filter via thecontrol valve.

Fuel temperature greater than 45 °C:

• The bimetallically-controlled control valve is fullyclosed; the full fuel return volume flows past the fuelfilter into the fuel tank.

Fuel filter with water-in-fuel sensor (certainmarkets only)

After installing a new fuel filter, a parameter reset ofthe values for the water-in-fuel sensor must be carriedout with the help of the IDS.


Denso common rail systemLesson 2 – Fuel System


Illustration shows the system in the 2.4L Duratorq-TDCi

E69809

High-pressure line1

Leak-off pipe2


Fuel injector4






Fuel pump10

Fuel return11


Lesson 2 – Fuel SystemDenso common rail system


After all work on the high-pressure system, a fuelsystem leak test must be performed with the help ofthe IDS.

Fuel pump

Illustration shows the fuel pump of the 2.4L Duratorq-TDCi

E69909

6

7

8

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C

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1112

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B

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1

14

2 3

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High-pressure fuel to the fuel railA

Fuel returnB

Fuel lineC

High-pressure chamber exhaust valve1

High-pressure chamber intake valve2

Pump plunger3

Fuel metering valve return spring4


Admission pressure control valve (pump interiorpressure)

6

Transfer pump (rotor pump)7

Fuel intake8

Fuel filter9

Eccentric cam ring10

Eccentric cam11

Halfshaft12

Fuel tank13

Overflow throttle valve14



Design

The fuel pump provides the interface between thelow-pressure and high-pressure systems. Its function isto always provide sufficient compressed fuel under alloperating conditions and for the entire service life ofthe vehicle.

Low-pressure part:

• The transfer pump draws fuel out of the fuel tankvia the fuel intake.

• The pump internal pressure is adjusted via theadmission pressure control valve. This ensures thatsufficient lubrication and cooling are alwaysprovided for the fuel pump components. Excess fuelis transferred to the intake side of the transfer pumpvia the admission pressure control valve.

• A portion of the fuel is transferred to the fuelmetering valve from the transfer pump. The fuelquantity delivered to the high pressure chambers isdetermined by the opening cross-section of the fuelmetering valve.

• The small restriction bore in the overflow throttlevalve provides for automatic ventilation of the fuelpump. The entire low-pressure system is designedto allow a defined quantity of fuel to flow back intothe fuel tank via the overflow throttle valve. Thisassists cooling of the fuel pump.

High-pressure part:

• A total of two high-pressure chambers, each withone pump plunger, are used for high-pressuregeneration.

• The pump plungers are driven via an eccentric cam,which is in turn driven by the halfshaft (principlesimilar to the Bosch common rail system).

• The fuel pump permanently generates the highsystem pressure for the fuel rail.



Principle of high-pressure generation

E69910

1 2

3

4

C

A

6

B

5

Pump plunger 1A

Pump plunger 2B

To the fuel railC

Intake valve1

Exhaust valve2

Eccentric cam3

Eccentric cam ring4


Halfshaft6



The rotary movement of the halfshaft is converted to areciprocating movement by the eccentric cam. Theeccentric cam ring transfers the reciprocating movementto the pump plungers.

The pump plungers are arranged offset by 180 degrees.This means that during a reciprocating movement, pumpplunger 1 performs exactly the opposite movement topump plunger 2.

The eccentric cam generates an "upward" stroke:

• Pump plunger 1 moves in the direction of TDC, thuspressurising the fuel and delivering it to the fuel railvia the exhaust valve. The intake valve is pressedinto its seat by the delivery pressure.

• Pump plunger 2 is moved by the tension spring forcein the direction of BDC. Due to the high pressure inthe fuel rail, the exhaust valve is pressed into its seat.The pump internal pressure opens the intake valveand fuel flows into the high-pressure chamber.

The eccentric cam generates a "downward" stroke:

• The process is the reverse to that previouslydescribed.

Programming the fuel pump (fuel meteringvalve)

After installing a new fuel pump/fuel metering valveand/or PCM, the fuel metering valve of the fuel pumpmust be programmed with the help of the IDS.


After installing a new fuel pump or fuel metering valve,the fuel pump must be adapted with the help of the IDS.

Fuel rail and high-pressure fuel lines

Fuel rail

1

23

4

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23

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E98851

High-pressure fuel lines (to the fuel injectors)1


Fuel rail3


High-pressure fuel lines (to the fuel pump)5




Pressure fluctuations are induced in the high-pressurefuel system due to the operating movements in thehigh-pressure chambers of the fuel pump and theopening and closing of the solenoid valves on the fuelinjectors.

Consequently, the fuel rail is designed in such a waythat, on the one hand, it possesses sufficient volume tominimise pressure fluctuations, but, on the other hand,the volume in the fuel rail is sufficiently low to buildup the fuel pressure required for a quick start in theshortest possible time.

The fuel supplied by the fuel pump passes through ahigh-pressure line to the high-pressure accumulator.The fuel is then sent to the individual fuel injectors viathe four fuel injection lines which are all the samelength.









The fuel pressure sensor must not be renewed separatelyin the event of a fault. The whole fuel rail must alwaysbe renewed in the event of a fault.

Pressure relief valve

The pressure relief valve opens at a fuel pressure ofabove 2,200 bar. It serves as a safeguard in the event ofa malfunction in the high-pressure system. This preventsdamage caused by excessive fuel pressure in thehigh-pressure system.

The pressure relief valve works as a disposable valve.This means that it must be renewed after it has beentriggered once, as it will no longer seal properly.

NOTE: The pressure relief valve cannot be renewedseparately during servicing. The entire fuel rail must berenewed in the event of a fault.

NOTE: Triggering of the pressure relief valve isfrequently caused by a defective fuel metering valve.

Any triggering of the pressure relief valve is detectedby the PCM, which then sets an appropriate DTC(Diagnostic Trouble Code) and actuates the MIL(Malfunction Indicator Lamp).



Fuel injectors

Design

E98372

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5

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3

89

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10

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11

Solenoid valve1

Fuel rail pressure2

Fuel strainer3

Piston rod4

Nozzle needle spring5

Nozzle needle6


Fuel rail pressure8

Valve seat9

Leak-off10

Control chamber11

NOTE: The combustion chamber seals must not bereused.

The exact procedure for the correct installation ofthe fuel injectors can be found in the current ServiceLiterature.

Start of injection and injected fuel quantity are adjustedvia the fuel injectors.



In order to achieve the optimal injection timing andprecise injected fuel quantity, special fuel injectors witha hydraulic servo system and electrical actuator unit(solenoid valve) are used.

The fuel injectors are actuated directly by the PCM.

The PCM specifies the injected fuel quantity and theinjection timing.

The fuel injectors are divided into different functionblocks:

• injector nozzle,


• solenoid valve.





Irregular idling.


Illustration shows top view of fuel injector

E69913

1

3

2

Solenoid valve connector1

16-digit correction factor2

Leak-off pipe connection3

After installing one or more new fuel injectors, thefollowing service functions must be performed with thehelp of the IDS:

• entry of the correction factors of the fuel injectorsand

• adaptation of pilot injection by the fuel injectors.

Entry of the correction factors:

Inside the hydraulic servo system there are variousrestrictors with extremely small diameters which havespecific manufacturing tolerances.

These manufacturing tolerances are given as part of acorrection factor, which is located on the housing of thefuel injector.

To ensure optimum fuel metering, the PCM must beinformed when a fuel injector is changed.

Furthermore, after new PCM software has been loadedvia IDS, the fuel injectors must also be configured withthis software.

This is achieved by entering the 16-digit correctionfactor into the PCM with the help of the IDS, takinginto account the relevant cylinder.

Note: If the correction factors are not entered properly,the following faults can occur:


• irregular idling,

• increased combustion noise,

• engine will not start.

Adaptation of pilot injection by the fuel injectors:

• The pilot injection of each fuel injector must beoptimally preset so that the engine runs with as littlecombustion noise as possible.

• The cylinder acceleration of each cylinder is recordedand if necessary the pilot injection adapted using the"Adaptation of pilot injection by the fuel injectors"service function.

• If adaptation of pilot injection by the fuel injectorsis not correctly completed, the combustion noise willbe louder.




1. Which of the following statements about the low-pressure system is incorrect?

a. Fuel lines may be blocked due to foreign bodies or bending.

b. The in-tank fuel pump supplies fuel to the high-pressure pump.

c. The fuel filter must be dewatered regularly within the specified maintenance intervals.

d. Faulty valves or pipes in the tank venting system can impair the flow of fuel through the low-pressuresystem.

2. Which of the effects listed does not apply to a blocked fuel filter?

a. Engine demonstrates increased knocking noise at partial load.

b. Engine has insufficient power.

c. Poor engine starting performance when both cold and hot.

d. Engine will not start.

3. What is the function of the transfer pump?

a. The transfer pump controls fuel supply to the high-pressure chambers.

b. The transfer pump delivers the required fuel to the fuel pump.

c. The transfer pump generates the high pressure required for injection.

d. The transfer pump cuts in as required when the high pressure in the fuel rail falls below a minimum.

4. Which of the following statements about the high-pressure system is true?

a. Bosch common rail systems have only solenoid valve-controlled fuel injectors.

b. The fuel rail is designed in such a way that pressure fluctuations are maximised.

c. After disconnecting a high-pressure fuel line, a new one must always be installed.

d. The fuel metering valve is part of the fuel rail and must not be renewed separately during servicing.


Lesson 2 – Fuel SystemTest questions

General

A B

C

A B

C

E97499

Bosch PCMA

Siemens PCMB

Denso PCMC

The PCM is the main component of the enginemanagement system. It receives the electrical signalsfrom the sensors and setpoint transmitters, evaluatesthem and uses them to calculate the signals for theactuators.

The control program (the software) is stored in amemory. The execution of the program is carried outby a microprocessor.

Sensors and actuators form the interface between thevehicle and the PCM as a processing unit.

The sensors, actuators and the power supply areconnected to the PCM via three multi-pin connectors.

Input signals

Input signals from the sensors can have different forms.

Analogue input signals

Analogue input signals can have any voltage valuewithin a given range. Examples of analogue inputsignals include:

• IAT (Intake Air Temperature),

• MAP (Manifold Absolute Pressure),

• ECT (Engine Coolant Temperature).

As the microprocessor of the PCM can only processdigital signals, the analogue input signals must first beconverted. This is performed internally in the PCM inan analogue-to-digital converter (A/D converter).

Inductive input signals

Inductive input signals are pulsed signals that transmitinformation about the engine speed and reference mark.Example of an inductive input signal:

• CKP.

The inductive signal is processed in an internal PCMcircuit. Interference pulses are suppressed and the pulsedsignals are converted into digital square-wave signals.

Note: Inductive sensing of the engine speed is beingused less and less in modern diesel engine managementsystems. Hall sensors are being used more and more tosense the engine speed.

Digital input signals

Digital input signals have only two states:

• ON or OFF.

Examples of digital input signals:

– CMP,

– CKP,

– PWM (Pulse Width Modulation) signal from an APP(Accelerator Pedal Position) sensor.

These signals can be processed directly by themicroprocessor.

Output signals

E51118

1

2

b

b

a

a


Lesson 3 – Powertrain Control Module(PCM)

PWM signal

Fixed frequencya

Variable switch-on timeb

Signal voltage1

Time2

The microprocessor transmits output signals to theactuators via specific output stages. The output signalsfor the actuators can also have different forms:

• Switch signals:

– switch actuators on and off, for example the A/Cclutch.

• PWM signals:

– are square-wave signals with a constantfrequency, but variable turn-on time. Using thesesignals, electro-pneumatic transducers forexample (e.g. boost pressure control solenoidvalve) or actuators (e.g. electrical EGR valve)can be actuated at any location.

– The duty cycle (length of the switch-on timerelative to the length of the switch-off time)determines the control current to the actuator.It is of critical importance here whether theactuator is actuated pulsed to ground or pulsed topositive.

– Pulsing to positive: long switch-on time = highcontrol current, short switch-on time = lowcontrol current.

– Pulsing to ground: In this case the switch-onvoltage is constantly applied to the actuator. Thecontrol current results from the switching time toground: short switching time to ground = lowcontrol current, long switching time to ground =high control current.

The high-performance components for direct actuationof the actuators are integrated in the PCM in such amanner that very good heat dissipation to the housingis ensured.

Diagnosis

In the case of sensor monitoring, the integrateddiagnostics are used to check if there is sufficient supplyto the sensors and whether their signal is in thepermissible range.

Using the control program in the PCM it is also possibleto check whether a sensor signal is within thepermissible range.

In the case of systems which work by means of a closedloop (e.g. the EGR system), deviations from a specificcontrol range are also diagnosed.

A signal path is deemed to be defective if a fault ispresent over a predefined period. The fault is then storedin the fault memory of the PCM together with freezeframe data (e.g. ECT, engine speed, etc.).

Back in working order recognition is implementedfor many of the faults. This entails the signal path beingdetected as intact over a defined period of time.

Fault handling: If a signal deviates from thepermissible setpoint value, the PCM switches to adefault value. This process is used, for example, for thefollowing input signals:

• ECT, IAT,

• MAP, BARO (Barometric Pressure),

• MAF (Mass Air Flow)

For some driving functions with higher priority (e.g.APP sensor), there are substitute functions which, forexample, allow the vehicle to continue to be driven tothe next Authorised Ford Dealer.

The ECM performs self-monitoring to ensure correctoperation. Malfunctions in the hardware or software ofthe PCM are displayed by means of a DTC. Additionalmonitoring (see below) is also performed:

Reference voltage monitoring

In the case of reference voltage monitoring, so-calledcomparators compare the individual reference voltagesfor the relevant sensors programmed in the PCM tocheck if they are within limits.

If a set reference voltage falls below a set limit, a DTCis stored and the engine is stopped.

EPROM (Erasable Programmable Read OnlyMemory) monitoring

The engine adjustment data and freeze frame data arestored in the EPROM.

The freeze frame data forms part of the EOBD. Incorrectentries are detected appropriately and indicated by adiagnostic trouble code.



Bosch common rail system

System with "solenoid valve-controlled" fuel injectors (1.6L Duratorq-TDCi (DV) diesel engine)

E70768

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242322

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PCM and peripheralsLesson 3 – Powertrain Control Module(PCM)

MAP sensor1


Combined IAT sensor and MAF sensor3

IAT sensor (only with DPF system)4


ECT sensor6

CMP sensor7

CKP sensor8

Stoplamp switch9

APP sensor10

BPP (Brake Pedal Position) switch11

DC motor for the EGR valve with integratedposition sensor

12

CPP (Clutch Pedal Position) switch13

Oil pressure switch14

Generator (input signal)15

Start inhibit relay16

Ignition lock17

Battery18

DC motor for intake manifold flap withintegrated position sensor (vehicles with DPF)

19

DC motor for charge air cooler bypass flap withintegrated position sensor (Emission StandardIV)

20

PCM with integrated BARO sensor21

CAN (Controller Area Network)22

DLC (Data Link Connector)23

Fuel injectors24

Boost pressure control solenoid valve25

Glow plug control module26


Cooling fan control and A/C compressor28

PCM relay29

Generator (output signal)30

Gateway (e.g. instrument cluster or GEM(Generic Electronic Module))

31



PCM and peripherals

System with "piezo-controlled" fuel injectors (2.2L Duratorq-TDCi (DW) diesel engine)

4

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17

E96169



HS CAN data bus input and output signals1

MS CAN data bus input signals2

Gateway (GEM)3

EOP (Engine Oil Pressure) switch4

MAF sensor5

ECT sensor6

CKP sensor7

HO2S (Heated Oxygen Sensor)8

IAT sensor9



Oil level/temperature sensor12

APP sensor*13

CPP switch14

GEM**15

Outside air temperature sensor16

PCM EDC 16 CP3917

Glow plugs18

Fuel injectors19

EGR valve with integrated position sensor20

Fan module21

Air conditioning clutch22

Turbocharger variable vane electrical actuatorwith integrated position sensor

23

Fuel pressure regulator24

Actuator motor for intake manifold flap withintegrated position sensor

25


* Transmits the following output signals:

• PWM signal to the PCM,

• analogue signal to the GEM.

** The PCM receives the following information fromthe GEM via hard-wired lines:

• PCM activation ("wake up" function),

• confirmation that the electric fuel pump is workingproperly,

• signal from the stoplamp switch.



PCM and peripherals


1.4L Duratorq-TDCi (DV) diesel engine/2.0L Duratorq-TDCi (DW) diesel engine

1

3

5

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8

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1920

21

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26

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E70402



MAF sensor1

MAP sensor (not on all versions)2


IAT sensor (not on all versions)4


ECT sensor6

CMP sensor7

CKP sensor8

Turbocharger position sensor9

APP sensor (2002.25 Fiesta)10

APP sensor (2003.75 C-MAX)11

Stoplamp switch12

BPP switch13

CPP switch14

VSS (Vehicle Speed Sensor) (vehicles with noABS (Anti-lock Brake System))

15


Ignition switch17

Vehicle battery18

Oil pressure switch (not on all versions)19

Instrument cluster20

DLC21

Generator control (Smart Charge)22

PCM23

CAN24

DLC25

Fuel injectors26

Turbocharger guide vane adjustment solenoidvalve (not on all versions)

27

Intake manifold flap solenoid valve (not on allversions)

28

EGR valve solenoid valve (not on all versions)29

Fuel pump actuator (fuel metering valve and fuelpressure regulator)

30

A/C compressor and fan control magnetic clutch31

Electric PTC (Positive Temperature Coefficient)booster heater (not on all versions)

32

PCM relay33

Glow plug relay34

Electrically controlled EGR valve (not on allversions)

35

Bypass solenoid valve36

Shut-off solenoid valve37

Electrically actuated intake manifold flap (1.4LDuratorq-TDCi (DV) diesel engine, EmissionStandard IV)

38



PCM and peripherals

1.8L Duratorq-TDCi (Kent) diesel engine

E70403

1

3

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9

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14 15 16

1718

19

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23 24

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MAF sensor1

MAP sensor2


IAT sensor4


CHT (Cylinder Head Temperature) sensor6

CMP sensor7

CKP sensor8

KS (Knock Sensor)*9

APP sensor10

Stoplamp switch11

BPP switch12

CPP switch13


Ignition switch15

Vehicle battery16


Gateway**18

Intake manifold flap position sensor (certainversions)

19

Electric EGR valve20

Generator control (Smart Charge)21

PCM22

CAN23

DLC24

Fuel injectors25

Intake manifold flap solenoid valve26

Fuel pump actuator (fuel metering valve and fuelpressure regulator)

27

A/C compressor and fan control magnetic clutch28

PCM relay29

Glow plug relay30

Turbocharger variable vane electrical actuator31

* The sensor is not supported by the PCMsoftware and therefore has no function in thesystem.

** Can be the instrument cluster or the GEM,for example.



PCM and peripherals


M

E70317

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CHT sensor1

MAPT (Manifold Absolute Pressure andTemperature) sensor

2

MAF sensor3

APP sensor4

Oil level/temperature sensor (certain versionsonly)

5

Stoplamp switch6

CKP sensor7

CMP sensor8


VSS (vehicles with no ABS)10


Water-in-fuel sensor (certain markets only)12

GEM13

Electric EGR valve with position sensor14

Ignition lock15

Fuel pump (with fuel metering valve and fueltemperature sensor)

16

PCM (BARO sensor integrated into the controlunit)

17

CAN18

DLC19

Turbocharger variable vane electrical actuator(certain versions only)

20

Fuel injectors21

Glow plugs22

Cooling fan module23

Cooling fan24

A/C cut-off relay (WAC)25

Air conditioning clutch26



PCM and peripherals

Idle speed control

The fuel consumption at idle is mainly determined bythe idle speed and the efficiency of the engine.

It is advantageous to have as low an idle speed aspossible, as idling is of considerable importance whendriving in dense traffic (for minimising fuelconsumption).

However, the selected idle speed must be sufficient toensure that, under any conditions (e.g. when the airconditioning is switched on or the vehicle electricalsystem is heavily loaded), it does not drop so low thatthe engine starts to run roughly or stalls.

To regulate the idle speed, the injected fuel quantity isvaried by the idle speed controller until the measuredactual engine speed is the same as the specified setpointengine speed.

The setpoint engine speed and the control characteristicare influenced by the CHT/ECT.

Other variables are:

• vehicle speed (engine speed compensation system),

• generator control (Smart Charge) – this can increasethe idle speed,

• speed control system.

Fuel metering calculations

Illustration shows the Siemens system

1

5

2 3

4

1

5

2 3

4

E98373

Pilot injection and main injection fuel quantity1

PCM2

CKP sensor3

ECT or CHT sensor4

Fuel injector5

Diesel engines normally run without the use of a throttleplate and therefore always operate with an excess of air.

The torque or power output of the diesel engine is onlychanged by the amount of fuel that is made available(injected fuel quantity).

Two different strategies are used when calculating thefuel metering:

• engine starting,

• engine running.

Start quantity

When starting the engine, the injected fuel quantity iscalculated as a function of coolant or cylinder headtemperature and engine speed. The start quantity is


StrategiesLesson 3 – Powertrain Control Module(PCM)

output from the time the ignition is switched on until aspecific minimum engine speed is reached. The driverdoes not have any influence on the start quantity.

Driving operation

Illustration shows the Siemens system

12

3

4

5

E98375

Pilot injection and main injection fuel quantity1

PCM2

CKP3

APP4

Fuel injector5

During normal driving operation, the injected fuelquantity is calculated from the following mainvariables:

• APP,

• engine speed.

In addition, the calculation of the injected fuel quantityis influenced by other variables (correction variables),such as engine temperature and boost pressure.

E47860

1 2

6

3 4

5

Calculation of accelerator pedal actuation1

Judder damper2

Calculation unit3

Limiter4

Signal to the injection pump5

Idle speed calculation6

While the engine is running, the PCM uses one of thefollowing calculations as a basis for fuel metering:

• calculation of idle speed,

• calculation of accelerator pedal actuation.

Both calculations are performed continuously in paralleland independently of each other.

The values calculated using the idle speed andaccelerator pedal actuation are compared with each otherby a calculation unit.

This calculation unit then decides which calculationshould be used as the output signal for the fuel injector.The calculation unit always chooses the larger value forthe injected fuel quantity.

Example: Engine cold – the idle speed calculation yieldsan idle speed of 1200 rpm and an injected fuel quantityof 7 mg. The accelerator pedal is pressed by a very smallamount, and the accelerator pedal calculation providesan injection quantity of 6 mg. As the value from theaccelerator pedal calculation is lower than the result forthe idle speed calculation, the idle speed calculationhas higher priority. If the accelerator pedal is movedfurther, and the accelerator pedal calculation providesa higher injected fuel quantity than the idle speedcalculation as a result, then the accelerator pedalactuation calculation takes priority.



Strategies

Calculation of fuel metering when the speedcontrol system is switched on

Example: The vehicle is travelling in 5th gear at a speedof 100 km/h (62 mph) with an engine speed of 2500rpm. Under these conditions, the speed control systemis now switched on.

Of the previously mentioned variables, it is the idlespeed calculation that determines the quantity ofinjected fuel required to maintain the desired speed.

This means that the speed in this instance is measuredvia the idle control system. If load conditions change(for example if driving uphill) the system attempts tomaintain the speed accordingly.

Once again, as the accelerator is pressed more, theaccelerator pedal calculation assumes a higher priorityagain. The idle speed calculation assumes its originalfunction until the next time the speed control system isswitched on.

Judder damper

Sudden actuation of accelerator

E47861

2

3

4

1

5

Engine speed1

Abrupt actuation of accelerator pedal (driverdemand)

2

Engine speed curve without active judderdamping

3

Engine speed curve with active judder damping4

Time5

There is a so-called software filter between theaccelerator pedal actuation calculation and thecalculation unit.

When the accelerator is actuated or released suddenly,this causes huge changes in injected fuel quantityrequirements and thereby also in the torque produced.

Owing to this abrupt load change, unpleasant judder ofthe powertrain is caused in the elastic mountings (enginespeed fluctuations). These are reduced by the judderdamper as follows:

• As engine speed increases, comparatively less fuelis injected, as engine speed decreases more fuel isinjected.

In addition, the software filter prevents an abrupt dropin engine speed during gear shifting.

Smooth-running control (cylinderbalancing)

In addition to the previously described external loadmoments, there are also combustion quality phenomenaand internal friction moments which need to be balancedout. These change slightly, but continuously, over theentire service life of the engine.

In addition, the individual cylinders do not generate thesame level of torque for the entire service life of theengine. The reason for this are the mechanical tolerancesand changes which occur during the service life of theengine. This could result in a rough-running engine,particularly at idle.

The smooth-running control system calculates theaccelerations of the crankshaft via the CKP sensor aftereach combustion process and compares them.

Based on the engine speed variations, the injected fuelquantity for each cylinder is adjusted individually sothat, as far as possible, all cylinders contribute equallyto torque control.

External intervention into the injectedfuel quantity

In an external intervention into the injected fuel quantity,the injected fuel quantity is influenced by anothercontrol module (e.g. traction control).

It informs the PCM if and how much the engine torqueand consequently the injected quantity needs to bechanged.



Controlling fuel injection

E47862

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2

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8

Top dead centre1

Pressure curve without pilot injection2


Pressure curve with pilot injection4

Nozzle needle lift5

Nozzle needle lift with pilot injection6

Nozzle needle lift with main injection7

Crankshaft angle8

The pilot injection brings about a preconditioning ofthe combustion chamber and also has the followingeffects:

• The compression pressure is raised slightly by theinitial reaction or partial combustion process, as aresult of which the ignition lag for main injection isshortened and the combustion pressure rise isreduced (softer combustion).

These effects diminish the combustion noise and theNOX emissions.

Controlling the injected fuel quantity and theinjection timing

Injection signal to the solenoid valve of the fuel injector

E47864

1 2

Interval between start of pilot injection and startof main injection

a

Interval between pilot injection and maininjection

b

Injected fuel quantity for pilot injectionc

Injected fuel quantity for main injectiond

Pilot injection timing (degrees crankshaft angle)1

Main injection timing (degrees crankshaft angle)2

With the common rail injection system, a small injectedfuel quantity for pilot injection is injected into thecombustion chamber prior to the main injection.

The PCM calculates the overall injected fuel quantityand the injection timing.

The timing of the pilot injection and main injectionis designed here to be variable. This means that thetiming and the duration of the pilot injection and maininjection can be optimally adapted to the operatingconditions.

The noise and exhaust emissions are thereby kept to aminimum.

Note: With certain systems, up to two pilot injectionprocesses are initiated depending on the enginespeed/load. The second pilot injection process leads toa further reduction in the noise and exhaust emissions.



Strategies

Controlling the fuel pressure

Schematic diagram of the Siemens common rail system

E70775

PCM1

Fuel pump2

High-pressure chambers for high-pressuregeneration

3

Fuel feed4


Fuel pressure regulator1) 2)6


Fuel rail8

Solenoid valve or piezo element9

Nozzle needle10

1) Only with the Siemens and the Bosch common railsystems with piezo-controlled fuel injectors.2) With the Bosch common rail system withpiezo-controlled fuel injectors, the fuel pressureregulator is installed in the fuel rail.

Function

The engine management system of the common railinjection system is capable of providing the optimumfuel pressure for each operating condition.

Depending on the system, the fuel pressure regulatorworks using the following components:

• Bosch common rail system with "solenoidvalve-controlled" fuel injectors:

– Fuel pressure sensor and fuel metering valve

• Bosch common rail system with"piezo-controlled" fuel injectors:

– Fuel pressure sensor, fuel metering valve and fuelpressure regulator



• Siemens common rail system:

– Fuel pressure sensor, fuel metering valve and fuelpressure regulator

• Denso common rail system:

– Fuel pressure sensor and fuel metering valve

Via the high-pressure chambers of the fuel pump, fuelis pressurised and fed to the fuel rail.

In the process, the delivery quantity and thus the fuelpressure is regulated by the fuel metering valve byvarying the opening cross section of the fuel meteringvalve accordingly.

The fuel pressure is regulated in such a way that theoptimum pressure is available for each operatingcondition.

On the one hand, this reduces the noise emission duringfuel combustion. On the other hand, the enginemanagement system can meter the fuel very precisely,which has a positive effect on exhaust emissions andfuel consumption.

The fuel pressure sensor continuously informs thePCM about the current fuel pressure.

With certain systems, the fuel pressure is additionallyregulated via a fuel pressure regulator. This allowsthe fuel pressure to be adapted even faster to changingoperating conditions.

The fuel pressure supplied to the fuel rail is dependenton the engine speed and engine load.

Stopping the engine

Because of the way the diesel engine works, the enginecan only be stopped by interrupting the fuel supply.

In the case of fully electronic engine management, thisis achieved by the PCM specifying an injected fuelquantity of 0. The fuel injectors are therefore no longeractuated and the engine is stopped.

Pressure drop after the engine is stopped

After the engine has been stopped, pressure is reducedthrough calibrated leakage in the fuel pump and the fuelinjectors. For safety reasons, a certain period of timestill has to elapse before the high-pressure system maybe opened (see the current Service Literature).



Strategies

EGR system

E51810

1

9

64

7

3

2

5

8

MAF sensor1

PCM2

Oxidation catalytic converter3

Turbocharger4

EGR valve actuator motor5

Position sensor (integrated in the actuator motor)6

Charge air cooler7

EGR cooler8

Intake manifold flap9

By using turbochargers, the temperatures in the engine'scombustion chambers rise with the torque and output.

This results in the increased formation of NOX in theexhaust gas. In order to keep this NOX content in theexhaust gas within required limits, the EGR system isbecoming increasingly important.

In the partial load range, exhaust gas recirculation isachieved by mixing the exhaust gases with the intakeair. This reduces the oxygen concentration in the intakeair. In addition, exhaust gas has a higher specific heatcapacity than air. The proportion of water in therecirculated exhaust gas also reduces the combustiontemperatures.

These effects lower the proportion of NOX and alsoreduce the amount of exhaust gas emitted.

The quantity of exhaust gas to be recirculated isprecisely determined by the PCM.

An excessive EGR rate would lead to an increase indiesel particulate, CO and HC emissions due to lack ofair. Furthermore, combustion would become unstabledue to a lack of O2 (Oxygen).

Modern EGR systems consist of the followingcomponents:

• MAF sensor,

• actuator motor-controlled EGR valve with

• integrated position sensor.



Actuator motor

The actuator motor itself is activated by the PCMdepending on requirements. The opening cross sectionof the EGR valve depends on the PCM control current(PWM).

MAF sensor

The quantity of exhaust gas recirculated when the EGRvalve opens has a direct influence on the MAF sensormeasurement.

During exhaust gas recirculation, the reduced air massmeasured by the MAF sensor corresponds to the valueof the recirculated exhaust gases. If the quantity ofrecirculated exhaust gas is too high, the drawn in airmass drops to a specific limit. The PCM then reducesthe proportion of recirculated exhaust gas. It is thereforea closed loop.

Position sensor

In the face of increasingly stringent emission standards,EGR control via the MAF sensor alone is reaching itslimits.

The position sensor in the EGR valve actuator motorunit supplies a further signal to the PCM for calculatingthe EGR rate.

This signal also allows light soiling on the EGR valveseat to be compensated. This guarantees a precise EGRrate, close to the operating limit.

Intake manifold flap

NOTE: Throttling of the intake air is only supportedwith certain versions.

A further step towards minimising NOX is the restrictionof intake air via the intake manifold flap.

By partial closing of the intake manifold flap a vacuumis generated behind the intake manifold flap. Thevacuum results in the exhaust gases being drawn in moreefficiently by the engine via the EGR valve, enablingthe EGR rate to be metered more effectively.

Effects of faults

The majority of malfunctions in the EGR system arebarely perceived by the driver. The only thing that canhappen is increased combustion noise during idling.

If, however, the EGR valve jams open or if excessivemetering by the PCM takes place, the followingsymptoms can occur:

• rough engine running,

• poor engine performance,

• increased emissions of black smoke.

Diagnosis

The EGR control works as a system. The interaction ofindividual components is monitored.

Malfunctions lead to increased exhaust emissions whichexceed the EOBD limits. Serious faults will also leadto the EGR system being switched off.

Since this is an emissions-related system, malfunctionsare indicated by the MIL.



Strategies

Boost pressure control

Illustration shows the boost pressure system for a turbocharger with variable turbine geometry and solenoid valvecontrol

E47870

2

3

1

4

6

78

5

Boost pressure control solenoid valve1

MAP sensor2

IAT sensor3

Charge air cooler (not on all versions)4

Vacuum actuator for variable turbine geometry5

Turbocharger6

PCM7

Vacuum pump8



Illustration shows the boost pressure system for a turbocharger with variable turbine geometry and turbochargervariable vane electrical actuator

E48186

1

2

4

5

3

T-MAP (Temperature and Manifold AbsolutePressure) sensor

1

Charge air cooler (not on all versions)2


Turbocharger4

PCM5

Purpose and function

On a variable turbocharger, the boost pressure isregulated by adjusting the guide vanes. The optimumboost pressure can therefore be set for every operatingcondition.

The boost pressure actual value is measured via theMAP sensor. The setpoint value is dependent on theengine speed and the injected fuel quantity as well asthe IAT and BARO correction factors.

In the event of a discrepancy, the guide vanes of thevariable-geometry turbocharger are re-adjusted via theboost pressure control solenoid valve or the turbochargervariable vane electrical actuator.

In the event of a malfunction of the boost pressurecontrol system, engine power is reduced via the fuelmetering system.

With wastegate turbochargers (not shown here), theMAP signal is used as a safety function if the wastegatedoes not open after a specified boost pressure has beenreached. The engine power is also reduced in this case.

Effects of faults

Faults in the boost pressure control result in reducedengine power output.

Diagnosis

Faults in the boost pressure control are detected by theMAP sensor.

If the actual boost pressure deviates from the setpointboost pressure from the map by a defined value, alimp-home program is activated in the PCM. Only a



Strategies

limited injected fuel quantity is permitted in thislimp-home program. This prevents engine damagethrough possible turbocharger overpressure.



General

E52683

The EOBD system does not use any additional sensorsor actuators to individually measure pollutants in theexhaust emissions.

The EOBD system is integrated into the software of thePCM and uses the existing sensors and actuators of theengine management system.

With the aid of these sensors, actuators and the specialsoftware, systems and components significant foremissions are continually checked during the journeyand exhaust emissions calculated accordingly.

Components significant for emissions are checked withthe so-called monitoring system.

With the introduction of EOBD for European Ford dieselengines as of January 1, 2004 this will comprise thefollowing monitoring systems (monitors):

• monitoring of components significant for emissions(Comprehensive Component Monitors = CCM),

• monitoring of the EGR system,

• boost pressure monitoring,

• fuel pressure monitoring.

Monitoring system for components significantfor exhaust emissions (CCM)

The monitoring system for components significant foremissions (CCM) continually checks to see if the sensorsand actuators significant for emissions are operatingwithin the specified tolerances when the engine isrunning.

If a sensor or actuator is outside the tolerance range,this is recognised by the monitor and a DTC is storedin the data memory.

Monitoring of the EGR system

The operation of the EGR system is monitored toidentify faults that lead to increased exhaust emissionsand may exceed the EOBD threshold values.

This monitoring system was developed so that it can,among other things, check the flow characteristics ofthe EGR system.

Boost pressure monitoring

Boost pressure control operates via the boost pressurecontrol solenoid valve and the MAP sensor in a closedloop.

The boost pressure is constantly monitored via the MAPsensor.

Fuel pressure monitoring

Fuel pressure regulation operates via the fuel meteringvalve and the fuel pressure regulator (certain systemsonly). Feedback regarding the current fuel pressure isreceived via the fuel pressure sensor.

MIL

E48311



EOBD

The MIL is located in the instrument cluster and showsan engine icon (international standard).

The MIL warns the driver that the EOBD system hasdetected an emissions-related fault in a component orsystem.

If an emissions-related fault is detected and if this faultis confirmed during the third driving cycle, the MILis switched on.

After the MIL has been switched on, a fault log iscreated in the PCM. The fault logs contain informationregarding the type of fault and the time since the MILwas activated.

The MIL ensures that a fault is recognised in time. Thedefect can be repaired in good time and the emission ofexhaust gas with high levels of pollutants is avoided.

Fault logging and storing

A fault occurring for the first time is labelled in thefreeze frame data as a suspected fault (pending code)and is stored in the data memory.

If the fault is not confirmed in the next check, it iserased.

If it is confirmed during the third drive cycle, thesuspected fault is automatically converted into aconfirmed fault (continuous code). The freeze framedata does not change. It remains the same as when thefault first occurred.

The MIL only illuminates when the fault has been storedas a confirmed fault.

If the fault does not recur in the course of threeconsecutive drive cycles, the MIL extinguishes in thefourth drive cycle. However, the fault code remainsstored in the data memory.

Faults which do not reoccur are automatically clearedfrom the memory after 40 warm-up cycles.

If a faulty signal is detected during a journey and thecorresponding fault code is stored, all the checks inwhich this signal is required as a comparison variableare interrupted. This prevents follow-up faults frombeing stored.

Diagnostic trouble codes can be read or cleared withthe WDS ( Worldwide Diagnostic System) Forddiagnostic tester.

Drive cycle

A drive cycle commences when the engine starts (enginecold or hot) and ends when the engine is stopped.Depending on the complexity of the fault, themonitoring period may vary:

• For simple electrical faults, a monitoring period ofless than five minutes is sufficient.

• For the purpose of monitoring a system (e.g. the EGRsystem) where different operating conditions, etc.are required to complete the test, the test can take upto about 20 minutes.

Warm-up cycle

A warm-up cycle starts when the engine is started, atwhich point the coolant temperature must be at least 22°C, and ends as soon as the coolant temperature exceeds70 °C.


EOBDLesson 3 – Powertrain Control Module(PCM)


1. PCM input signals

a. are always analogue signals.

b. are always digital signals.

c. can have different forms.

d. must always first be converted by an analogue-to-digital converter.

2. Which signal is used for smooth-running control?

a. CKP sensor

b. CMP sensor

c. MAP sensor

d. MAF sensor

3. How is the engine stopped?

a. By a shut-off valve.

b. Exclusively by closing an intake manifold flap.

c. The injected fuel quantity is gradually reduced to a minimum until the engine stalls.

d. The injected fuel quantity is set to 0, as a result of which the fuel injectors are no longer actuated.

4. When does the MIL indicate an emissions-related fault?

a. Immediately after the fault has occurred.

b. If the fault is confirmed after the second driving cycle.

c. If the fault is confirmed after the third driving cycle.

d. If the fault is confirmed after the second warm-up cycle.



Test questions

Introduction

Sensors record specific physical variables (e.g.temperature, pressure, engine speed, etc.) and convertthem into electrical signals.

Electrical signals can be:

• analogue voltage signals (e.g. a voltage between 0to 5 V),

• pulsed signals (e.g. from Hall sensors),

• frequency-modulated signals (e.g. from a digitalMAF sensor).

Depending on the requirement and complexity of thesensor, the electrical variables are transmitted directlyto the PCM as an output signal or first processed by thesensor electronics.

Example:

• An analogue voltage signal cannot be directlyprocessed by the PCM as it is. An analogue-to-digitalconverter in the PCM must first convert the rawsignal into the counts that the PCM can recognise.

• Some sensors generate electrical signals that cannotbe processed by the PCM (e.g. because the signal istoo unclear or too susceptible to interference). Thesesignals must be processed by electronics integratedin the sensor.

• Pulsed square-wave signals (e.g. signals from Hallsensors) can be processed directly by the PCM.

CKP sensor

Installation position

A

B

5

2

1 3

4

6

3

2

A

B

5

2

1 3

4

6

3

2

E97572

CKP sensor (inductive)A

CKP sensor (Hall)B

CKP sensor bracket1

CKP sensor2

CKP sensor retaining screw3

CKP sensor bracket retaining bolt (2 pieces)4

CKP sensor ring gear5

Ferro-magnetic magnet wheel6

Depending on the engine, the sensor is positioned asfollows:

• on the transaxle side: on the cylinder block, close tothe flywheel or

• on the front side: on the cylinder block, close to themass damper.


Lesson 4 – Sensors


Depending on the engine and common rail system,sensors with different operating principles are used:

• inductive sensor or

• Hall sensor.

The sensor scans a ring gear (inductive sensor) or aferro-magnetic polar wheel (Hall sensor) with a clearlydefined number of teeth or magnetic pole pairs(north/south).

Inductive CKP signal

E58343

(+)1 2

A

6

6

3

4

1 54

7

3

(-)

CKP signal (similar to sinusoidal voltagecharacteristics)

A

CKP sensor1

Voltage (volt)2

Pulses per crankshaft revolution (360 degrees)3

Reference mark (gap on the ring gear)4

Tooth centre5

Tooth interval6

Ring gear (flywheel or serrated disc)7

The signal frequency and the height of the signalamplitude increase in proportion to the engine speed.

The analogue sinusoidal signal is first converted intoa square-wave signal in the PCM. Only this signal canbe processed by the software.

CKP signal (Hall)

E58347

3

V5

2

4

1

Magnetic pole pairs (not visible) on magneticdisc

1

CKP sensor2

Clearance between the pole and the CKP sensor3

Pole gap/reference mark (not visible)4

Square-wave signal from the CKP (Hall) sensor5

In the case of Hall sensors, only the frequency of thesignal increases with the increasing engine speed.

The CKP signal is used:

• to determine engine speed,

• for synchronisation with the CMP signal,

• to determine the crankshaft position,

• to calculate the crankshaft acceleration.

The latter is used, for example, for smooth-runningcontrol (see "Lesson 3 – Powertrain control module(PCM)").

Effects of faults

The CKP signal is the main input variable for calculatingthe injected fuel quantity and injection timing.

In the event of a signal failure, the engine cannot bestarted or is stopped (injected quantity = 0).

Diagnosis

If a specified maximum time is exceeded after the lastCKP signal, there is a fault (plausibility check). Thischeck is capable of analysing driving errors (enginestalling or cutting out).



CMP sensor


1

23

A

B

4

3

2

1

23

A

B

4

3

2E97593

Example on the 2.0L Duratorq-TDCi (DW)diesel engine

A

Example on the 2.4L Duratorq-TDCi (Puma)diesel engine

B

Camshaft pulley with phase sensor for CMPsensor

1

Retaining bolt2

CMP sensor3

Left-hand intake cam on cylinder no. 44

The CMP sensor can be installed as follows:

• on the cylinder head, close to the camshaft pulley(all DV and DW diesel engines),

• on the intake side on the cylinder head, level withthe fourth cylinder (all Puma diesel engines),

• on the valve cover, level with the third cylinder (Kentdiesel engine).


The CMP signal is required by the PCM to activate theindividual fuel injectors according to the injectionsequence.

The sensor works according to the Hall principle.

The digital signal is used in combination with the CKPsignal to identify cylinder 1 (synchronisation with theCKP signal).

Effects of faults

When the engine is started, the synchronisation betweenthe CKP signal and the CMP signal takes place in thePCM.

If synchronisation cannot be completed successfully,no injection enable signal is sent by the PCM, and theengine does not start (injected fuel quantity = 0).

If synchronisation is successfully completed, the CMPsignal is of no consequence. This means that anypotential CMP signal loss while the engine is runninghas no effect.

Diagnosis

During engine starting, two signals (CKP and CMP) areexpected by the PCM.

After it has been ensured that the CKP signal is OK, thesystem is able to ascertain a fault in the CMP circuit.



MAP sensor


Illustration shows the sensor in the 2.0L Duratorq-TDCi(DW) diesel engine

E53690

1 2

MAP sensor1

IAT sensor2

The sensor is located in the air intake tract between thecharge air cooler outlet and the intake manifold.


The sensor has the following functions:

• measuring the current boost pressure,

• calculating the air density for adapting the injectedfuel quantity and the injection timing,

• calculating the turbocharger outlet temperature.

Effects of faults

In the event of a fault, the guide vanes of thevariable-geometry turbocharger are opened completely.Boost pressure is minimised. Furthermore, the EGRsystem is deactivated and the injected fuel quantity isappreciably reduced (reduced engine power output).

Diagnosis

Malfunctions lead to significantly increased emissions,as the EGR system is switched off and the boost pressurereduced to a minimum.

Monitoring of the sensor consists of altogether threechecking routines:

• The range check determines whether the sensorvalues are within the limits. If the limits are notachieved or are exceeded for a certain period, thePCM interprets this as an open loop or a short circuit.

• The rise/fall check identifies intermittent faults.These indicate a loose contact at the sensorconnector, among other things.

• The plausibility check compares the MAP sensorsignal with the BARO sensor signal.

The range check is activated when the ignition isswitched on, provided that no PCM power supply faultis present.

If the sensor voltage exceeds the maximum limit, thePCM interprets this as a short to positive.

If the sensor voltage is below the minimum limit, thePCM interprets this as an open loop or a short to ground.

The rise/fall check is also activated after the ignitionis switched on, provided there is no fault in the powersupply voltage to the sensor.

If the PCM identifies extreme, illogical voltage jumpsbelow/above the limits, a relevant DTC is stored.

The plausibility check takes place when the ignition isswitched on (engine off). The plausibility check is onlyperformed if the limit check was completed without anyfaults.

A prerequisite for this check, however, is that there isno plausibility fault entry stored in the fault memory ofthe PCM.

The PCM compares the current pressure at the MAPsensor with the pressure measured at the BARO sensorfor a defined period.



If the PCM detects an excessive deviation from thetarget map data, it concludes that the MAP sensor isdefective.

IAT sensor

Note: Not all versions are equipped with a separate IATsensor. For these versions the intake air temperature iscalculated by the IAT sensor integrated in the MAFsensor (see also "Combined IAT sensor and MAFsensor" in this lesson).


E98379

The sensor is located in the intake tract between thecharge air cooler outlet and the intake manifold.


The sensor contains a temperature-sensitive resistorwith an NTC (Negative Temperature Coefficient).

It detects the charge air temperature in order tocompensate for the temperature influence on the densityof the charge air.

The MAF signal influences the following functions:

• injected fuel quantity,

• injection timing,

• EGR system.

Effects of faults

In the event of a fault, the PCM operates using asubstitute value. This substitute value is derived fromthe ECT and fuel temperature.

Diagnosis

The PCM constantly checks whether the sensor valuesare within the limits.

If the maximum limits are exceeded for a determinedtime, this is interpreted by the PCM as an open loop ora short to positive.

If the minimum limits are not reached for a determinedtime, this is interpreted by the PCM as a short to ground.

The rise/fall check permits the system to detectintermittent faults (for instance a loose connectorcontact).

In vehicles with DPF system (Emission Standard IV)a further check, the plausibility check, has beenimplemented.

For the plausibility check, the signals of the ECT sensor,the fuel temperature sensor, the IAT sensor in the MAFsensor and the separate IAT sensor are compared withone another once the engine has cooled down. In thiscondition, the temperature values are approximately thesame.

If the check reveals that the IAT sensor value deviatefrom the other values by more than a specified limit,the IAT sensor is recognised as implausible and a DTCis stored.

MAPT sensor


E97599

The sensor is located in the intake tract between thecharge air cooler outlet and the intake manifold.


With this sensor, the MAP and the IAT sensors areintegrated in a single component.

See "MAP sensor" and "IAT sensor" in this lesson forthe respective functions.



BARO sensor


The sensor is integrated in the PCM.


The sensor measures the ambient air pressure.

With increasing geographical altitude, the air densityand therefore the air resistance decreases. This has aneffect on the engine cylinder charge and the turbochargerspeed.

To avoid damage to the turbocharger and increasedformation of black smoke, the sensor is integrated inthe PCM. It is used for making appropriate adaptationsto fuel metering and to exhaust gas recirculation.

Note for vehicles with 1.4L Duratorq-TDCi (DV)diesel engine with Emission Standard III:

• This version has no MAP sensor for detecting theboost pressure. In this version, the BARO sensorsignal is used together with the engine speed and airmass signals to calculate the boost pressure.

Effects of faults

In the event of a fault, the signal from the MAP sensoris used to determine the ambient air pressure.

If both sensors (BARO und MAP) are defective, thePCM uses a substitute value. In this case, the injectedfuel quantity and therefore engine performance issignificantly reduced.

Diagnosis

The PCM continuously checks the sensor for shortcircuits (to ground and positive) and for open loop.

The signal from the sensor is checked for plausibilityby performing a comparison test with the MAP signalin a specific low load range.

ECT sensor


E51427

The sensor is located in the small coolant circuit of theengine.


The sensor measures the current coolant temperature.It contains a temperature-sensitive resistor with an NTC.

The voltage value supplied by the sensor is assigned toa corresponding temperature value by the PCM.

The ECT is used for the following calculations:

• idle speed,

• injection timing,

• injected fuel quantity,

• EGR quantity,

• glow plug control,

• actuation of the temperature gauge and glow plugwarning indicator,

• fan control.

Effects of faults

When a sensor malfunctions or overheating of the engineoccurs, the "engine overheating" fail-safe mode isenabled.

In this mode, engine power is reduced by injecting lessfuel. If the engine temperature still continues to increase,the engine power output is decreased further still,depending on the vehicle version.

In fail-safe mode, the cooling fans run at maximumpower.



Diagnosis

As described previously, the engine coolant temperatureis used in a variety of calculations and thus has animportant effect on exhaust emissions.

In addition, the ECT is required to define the warm-upcycle.

The monitoring system continuously checks whetherthe values output by the sensor are within limits.

The PCM interprets deviations from limit values as anopen loop or a short circuit (to ground or to battery).

The sensor is checked for plausibility by a specificcalibrated temperature increase having to occur in a setperiod of time after the engine starts.

The plausibility check is only performed if the limitcheck was completed without any faults.

Plausibility check

E51125

T

1

4

3

2

t

5

Engine coolant temperatureT

Assumed engine coolant temperatureT1

Minimum temperatureT2

Minimum temperature not reachedT3

Timet

Timer1

Implausible temperature increase2

Expected minimum temperature increase3

Plausible temperature increase4

Timer cancellation5

Performing the plausibility check:

• After the engine has been started, the PCM assumesan ECT value.

• If the engine speed and the injected fuel quantityexceed a calibrated value due to the temperaturevalue assumption, a timer is started in the PCM.

• During timing, the PCM checks whether a sufficienttemperature increase and a calibrated minimumtemperature are reached.

• If this is not reached after timeout, an implausiblevalue is assumed and a DTC is stored.

• If, however, a sufficient temperature increase and acalibrated minimum temperature are reached duringtiming, the plausibility check is deemed to have beensuccessful and is stopped.

In the event of a fault, the engine management systemreverts to a substitute value and the engine runs atreduced power output. In this case, the cooling fans areswitched to run at maximum power.



CHT sensor (Kent and Puma dieselengines only)


E97602

A

B

CHT sensor in the1.8L Duratorq-TDCi (Kent)diesel engine

A

CHT sensor in the 2.2/2.4L Duratorq-TDCi(Puma) diesel engine

B

NOTE: A sensor that has already been removed maynot be reused.

The sensor is located at the transaxle end of the cylinderhead.


The CHT sensor is installed in place of the ECT sensorand the temperature sensor for temperature display inthe instrument cluster.

The CHT sensor is screwed into the cylinder head andmeasures the temperature of the material rather thanof the engine coolant.

As a result, when the engine overheats (e.g. due to lossof coolant) a more precise temperature measurement ispossible.

The sensor is a thermistor, i.e. a negative temperaturecoefficient resistor (NTC resistor).

E47841

J

J

1

2

3

5

8

4

6

7

PCM1

Second resistor ("pull-up")2

First resistor3

CHT sensor (NTC)4

Sensor output signal5

Analogue-to-digital converter6

Microprocessor7

For comparison: ECT sensor8

The output signal is an analogue voltage signal whichbehaves proportional to the resistance.

The voltage signal is digitised in the analogue-to-digitalconverter and transmitted in the form of counts to themicroprocessor, which assigns these to thecorresponding temperature values.

At high temperatures, the resolution of the CHT sensoris not high enough to adequately cover the entiretemperature range from –40 °C to +214 °C. Thereforethe temperature curve is shifted by switching on asecond resistor in the PCM.



Shifting of the characteristic in the Visteon system

E47842

-- --

(129)

A B

C

12

32

CountsA

Voltage (volt)B

Material (sensor) temperatureC

First characteristic1

"Pull-up" resistor switch point2

Second characteristic3

How shifting of the characteristic works is explainedbelow using the Visteon system as an example.

The first curve ranges from a material temperature of-40 °C to approx. +78 °C. A transistor in the PCM thenactivates a second, so-called "pull-up" resistor to extendthe sensor signal function. The second curve rangesfrom a material temperature of approx. 62 °C to 214 °C.

This means:

• in the warm-up phase, the "pull-up" resistor isactivated at 78 °C,

• in the cool-down phase, the "pull-up" resistor isdeactivated at 62 °C.

The activation and deactivation point are offset to oneanother (hysteresis). This prevents constant activationand deactivation during constant engine operation closeto the switching point.

Example:

• A sensor output voltage of 2.5 V (= 500 counts) canindicate a material temperature of 35 °C as well asone of 129 °C (see diagram), depending on whichcharacteristic the voltage value is assigned to.

• When the "pull-up" resistor is activated, themicroprocessor assigns the numerical value"500 counts" to the second characteristic curve. Thismeans that the material temperature is in the highertemperature range (in this case 129 °C).

Switch points with the Siemens system:

• Activation point: 85 °C

• Deactivation point: 80 °C

Use of the CHT signal:

• Injected fuel quantity

• Start of injection

• Idle speed

• Glow plug control

• EVAP system

• Actuation of the temperature gauge and glow plugwarning indicator

Effects of faults

Open loop:

• In an open loop, the system assumes a maximumtemperature value of 120 °C.

• In this instance, the cooling fan(s) will be runningcontinuously and the engine will be operating atreduced power (reduced injected fuel quantity).

Short circuit:

• If there is a short circuit, the system assumes atemperature greater than 132 °C.

• In this situation, the engine cuts out or cannot bestarted.

When a sensor malfunction or overheating of the engineoccurs, the engine overheating fail-safe mode is enabled.

In this mode, engine power is reduced by injecting lessfuel. If the engine temperature increases further, thenthe engine power is reduced further (depending on thevehicle version).



Note: To avoid engine damage, it is not possible to startthe engine at a cylinder head temperature below–35 °C. The reason for this is the large quantities of fuelinjected, which in this case might result in componentsbeing destroyed. Vehicles for cold climates have specialstrategies or engine preheating equipment.

Diagnosis

The monitoring system checks:

• the sensor for short circuit to ground/battery andopen loop,

• the sensor for illogical voltage jumps (illogicalvoltage jumps could indicate a loose connection, forexample),

• the signal for a plausible temperature increase.

Combined IAT sensor and MAF sensor


E70320

The sensor is located in the air intake tract, usuallydirectly behind the air cleaner.


Depending on the version, two different sensors areused:

• Analogue sensor – transmits an analogue voltagesignal to the PCM, where an analogue-to-digitalconverter converts the signal for further processing.

• Digital sensor – an integrated circuit in the sensorconverts the measured signal directly into a digitalsignal.

Note: In Emission Standard IV vehicles, a digital sensoris usually installed.

The sensor registers the mass air flow into the engine.The MAF signal is used:

• as a parameter for calculating the injected fuelquantity and the injection timing,

• for controlling the EGR quantity (closed loop withEGR valve).

There is an IAT sensor integrated into the MAF sensor.

The IAT sensor is used to correct the MAF signal atdifferent intake air temperatures.

If no separate IAT sensor is installed in the intakesystem downstream of the turbocharger, the IAT signalis also used for calculating the turbocharger outlettemperature. In this version, the calculated value servesas a correction factor for calculating the air densitydownstream of the turbocharger.

Effects of faults (MAF sensor)

If the signal fails, the PCM employs a substitute value,which is calculated from the engine speed and othervalues.

The substitute value does not, however, permit precisemetering of the EGR rate. Adherence to the exhaustemission levels is no longer possible and therefore theMIL is switched on.

Depending on the software strategy, the EGR systemcan also be switched off completely.

Effects of faults (integrated IAT sensor)

In the event of a fault, the PCM performs thecalculations using a substitute value.

Furthermore, if installed, the thermo managementsystem is controlled via a limp-home map. If installed,the electric PTC booster heater is switched off.

Diagnosis (MAF sensor)


• the sensor for short to ground/battery (by means ofa limit range check) and open loop,

• the logical rise/fall rate of the signal, wherebyintermittent faults are detected (e.g. loose connectorcontacts).

• for plausibility of the signal (only 1.4LDuratorq-TDCi (DV) diesel engine, EmissionStandard IV).



During a test cycle, the current maximum and minimumvalues are compared over a specified period for the limitrange check.

If a value exceeds/falls below the calibrated range duringthis test cycle, the test cycle is deemed to be faulty anda test cycle counter is activated.

For a certain number of test cycles, the "sound" and"faulty" test cycles are recorded, evaluated andcompared with one another.

The ratio of faulty test cycles to the total number of testcycles is calculated. If the result exceeds a calibratedlimit, a DTC is immediately stored.

The increase check (for intermittent faults) works in asimilar manner.

Malfunctions of the sensor have a significant influenceon exhaust gas emissions if the recirculated exhaust gasquantity cannot be controlled precisely.

An excessively low EGR quantity causes a dramaticincrease in the NOX emissions, on the other hand anexcessively high EGR quantity causes an increase indiesel particulate emissions.

Diagnosis (integrated IAT sensor)

The monitoring system checks the integrated sensor:

• for short circuit and open loop (via the limit rangecheck),

• the logical rise/fall rate of the signal, wherebyintermittent faults are detected (e.g. loose connectorcontacts).

HO2S


E96307

The HO2S is located in the exhaust tract, downstreamof the TC (Turbocharger).




The fuel injectors as well as parts of the enginemanagement system are subject to a certain agingprocess over the course of time. This gives rise tovariations when it comes to metering fuel as well ascalculating the mass air flow.

The broadbandHO2S measures the residual oxygencontent in the exhaust gas. The air/fuel ratio (lambda)can be deduced from this.

A more precise setpoint mass air signal can be formedfor exhaust-related control circuits in accordance withthe measured values. The correction of the exhaustgas recirculation has the greatest influence on this.

Sensing of the oxygen content in the exhaust gastherefore permits a narrower tolerance band for therecirculated exhaust gas. This has a positive effect onthe exhaust emissions.

The signal from the HO2S depends on the oxygenconcentration in the exhaust gas as well as on theexhaust gas pressure.

The residual oxygen in the exhaust gas can be used toperform a comparison between the EGR setpoint mapdata (determined via the mass air signal) and the dataactually detected.

The difference is stored in an adaptation map in definedlearning points.

This ensures fast and immediate correction of the massair calculation, even with sudden changes in operatingcondition.

The correction quantities are stored in the EEPROM ofthe PCM.

Effects of faults

In the event of a fault, the emissions values increaseslightly.

Diagnosis

Monitoring of the HO2S comprises the followingchecks:

• short circuit, open circuit and open loop (includesthe oxygen sensor heater circuit and the integratedsensor circuit),

• resistance check of the Nernst oxygen cell (cannotbe measured during servicing),

• signal plausibility.

Turbocharger position sensor (certainversions only)

Note: The sensor is only used in the 2.0LDuratorq-TDCi (DW) diesel engine.


E53955

1

2

3

Turbocharger position sensor1

Turbocharger vacuum actuator2

Variable-geometry turbocharger3

The sensor is located at the end of the vacuum actuatorof the variable-geometry turbocharger.


The PCM uses the sensor to obtain the exact positionof the turbocharger guide vanes. This further optimisesthe boost pressure control. This has a positive effect onexhaust emissions and fuel consumption.



The sensor is directly connected to the diaphragm in thevacuum actuator. When the guide vanes are adjusted(by means of a vacuum via the boost pressure controlsolenoid valve), the PCM determines the exact positionof the guide vanes via the turbocharger sensor.

Effects of faults

No substitution strategies are available in the case of afault. Following the detection of a fault, the boostpressure control switches to open loop.

The PCM treats this fault in the same manner as a MAPsensor fault and reduces the engine power output(reduction of injected fuel quantity).

Diagnosis

Monitoring of the sensor comprises the followingchecks:

• Short circuits and open circuits. A check is carriedout to see if the signal falls within its limits.

• Logical rise/fall rate of the signal. Intermittent errors(e.g. loose contact for a plug) are determined.

• End stop adjustment for fully opened guide vanes.If too great a deviation is detected during end stopadjustment, it indicates a blockage to the adjustmentof a vane.

• Control deviation check. A check is made via thesensor as to whether the guide vanes adopt thecorrect position smoothly during adjustment.

Typical malfunction limits:

• Rise/fall rate = 2 V / 10 ms

• Control deviation > ± 30%

Vehicle speed signal


E53694

2

1

3

Wheel speed sensors1

ABS module2

PCM3

There are two methods available for detecting thevehicle speed:

• using a VSS on vehicles with no ABS,

• using the wheel speed sensors for vehicles with ABS.

The signal from the wheel speed sensors is transmittedvia the CAN data bus. The PCM calculates the vehiclespeed from this.

The vehicle speed signal is used by the PCM to calculatethe gear engaged and as information for the speedcontrol integrated in the PCM.

For calculation of the vehicle speed, the wheel speedsof both front wheels are detected and an average valueis calculated.

If one or both front wheel speed sensors are faulty, thesignals of both rear wheel speed sensors are used andtheir average is used as the vehicle speed value. If afault occurs with the wheel speed sensors, a reliablevehicle speed signal can no longer be calculated.

Effects of faults

Increased idling speed

Uncomfortable juddering when changing gears

Speed control system inoperative (if installed)

Traction control inoperative (if installed)

Reduction of injected fuel quantity



Diagnosis

The vehicle speed signal has only minor effects onexhaust gas emissions and does not exceed the EOBDlimits.

The vehicle speed signal is, however, part of the freezeframe data and is part of the EOBD. In the event of afault, the MIL is switched on.

APP sensor


E43365

The sensor forms one unit with the accelerator pedal.


The sensor forwards the driver's acceleration request tothe PCM.

Two different sensor types are used:

• sensor with sliding-contact potentiometers (1.4LDuratorq-TDCi (DV) diesel engine only),

• inductive sensor.

Sensor with sliding-contact potentiometers:

• The sensor is a variable resistor which changes itsresistance in response to changes in the acceleratorpedal angle.

• For safety reasons, the sensor contains twopotentiometers (APP 1 and 2).

Inductive senor:

• The sensor detects changes in the accelerator pedalangle inductively. The strength of the inductiondepends on the position of the accelerator pedal.

• For safety reasons, the sensor is designed as ainductive double sensor (APP 1 and 2).

Function of the inductive sensor within the system

E70899

In this system, the signal from APP 1 is transmitteddirectly as a pulse width modulated signal to the PCM.

The APP 2 signal is transmitted as an analogue signalto the gateway (can be the instrument cluster or theGEM).

In the gateway, the APP 2 signal is digitised, then putonto the CAN data bus and transferred to the PCM.

Effects of faults

Sensor with sliding-contact potentiometers:

• If a potentiometer fails, the engine runs at reducedpower output, i.e. at a maximum engine speed of2750 rpm.

• If both potentiometers fail, the engine runs at aconstant engine speed of approx. 1200 rpm.



Inductive senor:

• If one of the two sensors is faulty, the engine runsat reduced power output. However, it is still possibleto achieve top speed.

• If the vehicle is equipped with a driver informationsystem, the fault message: "REDUCEDACCELERATION" is displayed.

• If the sensor fails completely, the engine is regulatedto a speed of up to 1200 rpm after the BPP switchand the stoplamp switch have been actuated onceand a plausibility check has been carried out. Thevehicle can be accelerated to a maximum speed of56 km/h.

• If the vehicle is equipped with a driver informationsystem, the error message "LIMITED TOP SPEED"is displayed.

• If the vehicle is not equipped with a driverinformation system the "engine system fault"warning lamp illuminates when a system erroroccurs.

Diagnosis



• the values of APP 1 and 2 for plausibility.

Fuel temperature sensor

Function

B

A

1

1

2

E85051

Fuel temperature sensor in the fuel returnA

Fuel temperature sensor at the fuel pump (Densosystem only)

B


Branch in the fuel return2

The sensor is located in the fuel return or directly at thefuel pump.


The sensor measures the fuel temperature in thelow-pressure system.

With the help of this signal, the fuel temperature iscontinuously monitored to prevent overheating of theinjection system. Furthermore, the fuel density as afunction of the temperature is taken into considerationwhen calculating the injected fuel quantity.

The critical fuel temperature is approx. 90 °C. Whenthe maximum fuel temperature is approached, the fuelpressure or the injected fuel quantity is limitedaccordingly.

Effects of faults

Bosch and Denso systems:

• In the event of a fault, the PCM assumes themaximum value. The fuel pressure and the injectedfuel quantity are then reduced.



Siemens system:

• In the event of a fault, the PCM performs thecalculations using a substitute value. The substitutevalue is calculated from the signal from the IAT andthe ECT sensors.

Diagnosis

The monitoring system continuously checks if the signalis within the limits as well as for short circuit and opencircuit.

Faults in the sensor have no effect on the exhaust gasemissions.



Illustration shows the fuel pressure sensor on the fuel railof the 2.0L Duratorq-TDCi (DW) diesel engine

E43239

1


The sensor is located on the fuel rail.

Note:

• The sensor must on no account be removed from thefuel rail during servicing. In the event of a fault, theentire fuel rail must be renewed.


The sensor very accurately and quickly measures theinstantaneous fuel pressure in the fuel rail and deliversa voltage signal to the PCM.

The fuel pressure sensor operates together with thefuel metering valve (and, if installed, the fuelpressure regulator) in a closed loop.

The sensor signal is used to:

• determine the injected fuel quantity,

• determine the start of injection,

• actuate the fuel metering valve and, if present, thefuel pressure regulator.

Effects of faults

The fuel pressure is a critical value. If the signal shouldfail, it is no longer possible to carry out pressureregulation and a controlled injection process.

Different measures appropriate to the system are takento protect the injection system from major damage.

Bosch common rail system:

• In the event of a short circuit or open loop, the PCMassumes a fuel pressure that is higher than themaximum permissible pressure. In response, theinjected fuel quantity is set to 0 and the engine isstopped or cannot be started.

• The injected fuel quantity is also set to 0 if valuesare implausible.

Siemens and Denso common rail systems:

• In the event of a fault, the PCM switches from closedloop to open loop and performs calculation using anaverage value (Siemens approx. 350 bar/Densoapprox. 600 to 1000 bar), which is made availablevia a limp-home characteristic map.

• The average value used is within a safe range (inorder to prevent excessive pressure). This means thatthe injected fuel quantity and therefore the engineperformance are restricted.

• Note: For a quick check of the sensor, disconnectthe wiring harness connector while the engine isrunning. The engine should run more roughly. Afterreconnecting the wiring harness connector, theengine should return to smooth running.

Diagnosis

Monitoring of the sensor comprises the followingchecks:

• short circuit, open circuit, open loop (via the limitrange check),

• logical rise/fall rate of the signal (loose contactdetection)



• sensor-specific signal fluctuations,

• correct pressure reduction after the engine is stopped.

Monitoring of the sensor-specific signal fluctuationsserves to check whether the signal emitted by the sensoris subject to "normal fluctuations".

A precondition for this check is that no faults are presentin the sensor supply voltage and that there is no short,open circuit or open loop. Moreover, the engine mustbe running in the partial load range.

During monitoring, the PCM checks whether the signalfluctuations emitted by the sensor are within a calibratedminimum limit. If the fluctuations are inferior to thecalibrated minimum limit, a DTC is stored.

This is in order to check whether the sensor is stickingat a certain point when emitting the signal.

Monitoring for correct pressure reduction is performedafter the engine is switched off using the ignition key(ignition OFF) as well as if the engine cuts out (ignitionON or OFF).

The PCM checks for pressure reduction in thehigh-pressure system.

When the engine is stopped, a timer is activated. Thefuel pressure present at timeout is registered andcompared with the calibrated limit in the PCM. If themeasured value exceeds the calibrated limit, this leadsto a DTC being stored.

Engine oil level sensor (2.4L/3.2L Duratorq-TDCi (Puma) diesel engine)


E64597

1

23

Engine oil level sensor1

Openings2

Oil dipstick3



At the time of going to print, the following versions areequipped with this sensor:

• 2.4L Duratorq-TDCi (Puma) diesel engine with 103kW (140 PS) and

• 3.2L Duratorq-TDCi (Puma) diesel engine with 147kW (200 PS).

The sensor is installed at the cylinder block on the intakeside and projects into the oil pan.


E70772


Wire loop2

Temperature sensor (NTC)3

Sensor body4

The quality of the engine oil is calculated using thissensor and a strategy implemented in the PCM. Thismeasure is also able to increase the oil change intervalsin this version.

Furthermore, the driver receives an indication via thedriver information system when the engine oil level hasdropped below the limit.

The engine oil level sensor comprises a wire loop,which is immersed in the engine oil to a greater or lesserextent corresponding to the oil level.

At the time of the oil level measurement, a regulatorcircuit in the PCM closes the circuit of the wire loop.The regulator circuit regulates a constant current flowof 195 mA through the wire loop.

The constant current flow heats the wire loop in aspecific way.

The voltage drop (U0) across the wire loop is measuredimmediately after the circuit closes. Anothermeasurement (U1) takes place approximately 1.75seconds later.

Between the first measurement (U0) and the secondmeasurement (U1) there is a temperature drop at thewire loop. It is dependent on the extent to which thewire loop is immersed in the engine oil.

The temperature drop results from the dissipation ofheat from the wire loop to the engine oil. Thistemperature drop causes a change in resistance of thewire loop and thus also a change in the voltage drop.

The voltage drop is used by the PCM as an indicatorfor calculating the oil level and the oil quality.

The integral temperature sensor measures the currentengine oil temperature and is used as a correction factorfor the oil level calculation.

Prerequisites for the measurement

Two conditions must be satisfied in order to ensure themeasurement is correct:

• The engine must be stopped for a period of 90seconds. This provides an adequate return flow ofengine oil into the oil pan. In this time, the powersupply of the PCM is maintained (power latchphase).

• The vehicle must be standing on a horizontal surface.

After completing the second measurement, the PCMcalculates the oil level. The calculated value is stored.



Strategy for determining a horizontal surface

E70773

3

4

1

2

Reference voltageVref

Signal to the GEMS

Instrument cluster1

PCM2

GEM3


In order to ensure a correct measurement of the oil level,the strategy of the PCM must be certain that the vehicleis standing on a horizontal surface. It assumes that thepump area of a filling station has this type of surface.

For this purpose, the signal from the fuel pump andsender unit is used.

If, following "ignition ON", the fuel level is significantlyhigher than at the last "ignition OFF", the PCM assumesthat the vehicle is at a filling station and, therefore, isstanding on a level surface.

The last oil level measurement that was stored at thelast "ignition OFF" is classified as a validmeasurement.

Only this oil level measurement is used for thecalculations.

Registering an oil level that is too low

If the PCM has detected refilling of the vehicle fueltank, the last oil level measurement is compared withthe map data.

If the measured values indicate an oil level which is toolow, a corresponding indicator/text message is displayedon the driver information system.

The indicator/text message illuminates/appearsimmediately after "ignition ON" and remains activeuntil the next "ignition OFF".

For the next "ignition ON" the lamp/text message isthen no longer active.

Note: Even if the engine oil has not been topped up, theindicator/text message is not active again.

Calculation of the oil quality

A strategy is implemented in the PCM that calculatesthe optimal time for an oil change.

This calculation is based on the continuous detection ofthe engine operating conditions as well as the last validoil level measurement.

If this data reveals an oil change is necessary, then thisis indicated via an indicator/text message in theinstrument cluster.

Note: After every oil change, the parameters for the oilquality calculation must be reset (see the current ServiceLiterature).

Engine oil level sensor (2.2LDuratorq-TDCi (DW) diesel engine)

NOTE: The sensor contains a wire loop for measuringthe oil level and a temperature sensor. The sensor istherefore able to transfer two input signals to the PCM.With this system, however, the PCMonly picks up thesignal from the temperature sensor.




E96189

The sensor is located at the lower end of the cylinderblock and projects into the oil pan.


The signal from the engine oil level sensor serves as aninput variable for calculating the engine oil dilution bythe fuel (vehicles with DPF).

Reasons for use:

• One or even two post-injection processes are usedin some cases to raise the exhaust gas temperatureduring regeneration of the DPF.

• In particular, the second, so-called retarded,post-injection is not ignited in the combustionchamber. Some of the fuel particles collect on thecylinder walls and get into the crankcase via thepiston rings and therefore into the engine oil.

• The engine oil temperature measurement is one ofthe input variables for the PCM for calculating theengine oil dilution by fuel.

• The degree of oil dilution is mainly dependent onthe engine's operating conditions. If post-injectionprocesses are frequently required for regenerationof the DPF, the engine oil dilution is correspondinglyhigh.

• This can lead to the vehicle having to be brought forservicing at an earlier oil change interval.

• If the PCM detects excessive oil dilution, this isshown in the instrument cluster via an indicator lightand a text message.

Function

E70772


Wire loop (signal is not picked off by the PCM)2

Temperature sensor (NTC)3

Sensor body4

The sensor is designed as an NTC and is immersed inthe engine oil in the oil pan.

The resistance falls as the engine oil temperatureincreases, the resistance increases as the engine oiltemperature falls.

Effects of faults

If the signal fails, a corresponding text message is shownin the instrument cluster display.

The PCM uses a substitute value for further calculation.



Diagnosis

The sensor is monitored by the PCM for short circuitand open circuit.

Service instruction

The parameters for the engine oil dilution calculationmust be reset after every oil change (see the currentService Literature).

Oil pressure switch

E52848

3

1 2

PCM1

Instrument cluster2


The oil pressure in the engine's oil circuit is monitoredvia the oil pressure switch.

If the oil pressure is incorrect, this is detected by the oilpressure switch, which then transmits a signal to thePCM.

In the PCM, the signal from the oil pressure switch isplaced on the CAN data bus and forwarded to theinstrument cluster, causing the oil pressure warningindicator to illuminate.

There is no fault strategy implemented.

Stoplamp switch/BPP switch


Illustration shows the BPP switch

E43363

Both switches are installed on the pedal mounting, nearthe brake pedal.

Function

The signal of the stoplamp switch influences fuelmetering when the brake is applied and a gear is engagedat idle speed.

Example: During braking, the PCM receives a signalfrom the stoplamp switch which results in the fuelquantity for idle control being reduced. This preventsthe idle control system from continuing to maintain idlespeed and counteracting the braking action.

In addition, there is a BPP switch installed. In vehicleswith a speed control system, the stoplamp switch andthe BPP switch both send the "brake applied" signal tothe PCM for safety reasons.

In addition, the signals from both switches are used tocheck the APP sensor (plausibility check).



CPP switch


E51434

At the pedal mounting, near the clutch pedal.

Function

Using the CPP switch, the PCM identifies whether theclutch is engaged or disengaged.

The quantity of injected fuel is briefly reduced duringactuation of the clutch to avoid engine judder duringgearshifts.

The CPP switch is located on the pedal box assembly.

On vehicles with speed control, the CPP switch switchesoff the speed control when the clutch is disengaged.

Effects in case of fault

Engine judder during gearshifts.




1. What is avoided with the aid of the BARO sensor in the PCM?

a. Excessively high engine speeds which cause the engine to overheat at increasing geographic altitudes.

b. Charge air cooling at increasing geographic altitudes.

c. Damage to the turbocharger and black smoke formation at increasing geographic altitudes.

d. Damage to the EGR system at increasing geographic altitudes.

2. How does the PCM respond if the MAP sensor is faulty?

a. Engine performance is reduced considerably.

b. Boost pressure is limited to a maximum of 2.0 bar.

c. The BARO sensor signal is used as a substitute value for boost pressure control.

d. The MAF sensor signal is used as a substitute value.

3. Which of the following statements about the APP sensor is true?

a. The APP sensor comprises a total of three sensors.

b. APP sensor 1 runs directly to the PCM; APP sensor 2 runs directly to the gateway, and from there to thePCM.

c. The APP sensor comprises a total of two sliding-contact sensors and one inductive sensor.

d. If one of the two sensors on the APP sensor fails, the engine continues to operate unaffected.

4. What does the HO2S signal affect in the 2.2L Duratorq-TDCi (DW) diesel engine?

a. Boost pressure control

b. Fuel pressure control

c. Exhaust gas recirculation

d. Homogeneous mixture formation


Test questionsLesson 4 – Sensors

Fuel metering valve


A B

C

A B

C

E98028

Denso fuel pumpA

Bosch fuel pump (CP1H)B

Siemens fuel pump (DW diesel)C

The fuel metering valve is bolted onto the fuel pump.


The fuel metering valve controls the fuel feed to thehigh-pressure chambers of the fuel pump via an openingcross section.

The larger the cross section of the opening, the greaterthe fuel pressure generated by the fuel pump.

In the case of systems without a fuel pressureregulator, the opening cross section of the fuel meteringvalve directly determines the fuel rail pressure.

Illustration shows the structure of the fuel metering valve in the Bosch common rail system

E51239

1 6 6

7

4

5

2

3

Coil1

Wiring harness connector connection2

Valve needle3

Valve closed4

Maximum opening cross section5

From the transfer pump6

To the high-pressure chambers7


Lesson 5 – Actuators

The fuel metering valve is controlled by PWM signalsfrom the PCM. The type of PWM is a function of:

• driver's requirements,

• fuel pressure requirement,

• engine speed.

The PWM determines the opening cross section of thefuel metering valve.

NOTE: Depending on the common rail system, the fuelmetering valve is either fully closed or fully open whende-energised (see table on next page).

Fuel metering valvewhen de-energised

Common rail system

fully openBosch (DV diesel engine)

• Fuel pump CP3.2

fully closedBosch (DV diesel engine)

• Fuel pump CP1H

fully openBosch (DW diesel engine)

fully closedSiemens

fully openDenso

The type of PWM by the PCM depends on the positionof the fuel metering valve when de-energised.

Effects of faults

Malfunctions (e.g. a hesitant or jammed fuel meteringvalve) and control faults are detected by continuallycomparing the fuel pressure requirement (calculated bythe system) and the actual fuel pressure (measured inthe fuel rail).

Bosch and Siemens common rail systems:

• In the case of serious malfunctions, the injected fuelquantity is set to 0 (engine is stopped or cannot bestarted).

• In the case of control faults that exceed a specifictolerance range, the injected fuel quantity is alsoset to 0.

• In the case of control faults within a specifictolerance range, the injected fuel quantity and thusthe engine performance is reduced.

Denso common rail system:

• In the case of control faults that exceed a specifictolerance range as well as in the case of seriousmalfunctions, the engine performance issignificantly reduced.

• The engine continues to run, but combustion noiseis louder.

• Note: This system features a mechanical pressurerelief valve. Malfunctions in the fuel metering valvegenerally trigger the pressure relief valve. When thepressure relief valve is triggered, the PCM sets theDTC P0089. If P0089 is displayed when reading outthe error memory, the pressure relief valve must berenewed along with the fuel metering valve.

Diagnosis

NOTE: In the strategy, the fuel metering valve, the fuelpressure regulator (if installed) as well as the fuelpressure sensor operate in close interdependency andshould therefore not be treated separately during faultanalysis (see also "Lesson 3 – Powertrain control module(PCM)", section "Controlling the fuel pressure").

The injected fuel quantity mainly results from the enginespeed and the opening time of the fuel injector,depending on the fuel pressure in the fuel rail. The fuelpressure therefore has serious effects on the exhaust gasemissions.

Monitoring of the fuel pressure is a feature arising fromthe interaction of the fuel metering valve (adjustingthe delivery quantity for the fuel rail) and the fuelpressure sensor (adjusting the desired fuel pressure).

From the output shape of the pulse width modulatedsignals, the monitoring system identifies (by comparingit with the setpoint map data) whether the actuation iswithin the limits.

In addition, short circuits (to ground and battery) andopen circuits are monitored.


Depending on the fuel system, the fuel metering valvecan be renewed separately. With other systems,however, the entire fuel pump must be renewed. In thisregard, always refer to the instructions in the currentService Literature.



Denso and certain Siemens systems only:

• After installing a new fuel pump or fuel meteringvalve and/or PCM, the new fuel metering valve mustbe programmed with the help of the IDS.

Fuel pressure regulator

Note: A fuel pressure regulator is only installed insystems with piezo-controlled fuel injectors.


A

B

A

B

E98146

Siemens systemA

Bosch system with piezo-controlled fuel injectorsB

The fuel pressure regulator is located

• at the fuel pump (Siemens system) or

• at the fuel rail (Bosch system).

Purpose and function (Siemens system)

The fuel pressure regulator regulates the fuel pressureat the high-pressure outlet port of the fuel pump andconsequently the pressure in the fuel rail. In addition,

pressure fluctuations arising during fuel supply and theinjection process are compensated by the fuel pressureregulator.

The fuel pressure regulator is actuated by the PCM sothat the optimum fuel pressure is present in the fuel railfor all engine operating states.

The fuel pressure regulator is actuatedelectromagnetically and is closed and opened in acontrolled manner via pulse width modulated signalsby the PCM. The variable actuation of the valve is afunction of

• driver request,

• fuel pressure requirement and

• engine speed.

Fuel pressure regulator not actuated

E53953

2

3

1

2

4

Fuel pressure at the high-pressure outlet port ofthe high-pressure pump

1

To the fuel return2

Valve ball3

Compression spring (partial section shown)4

The valve ball is pressed into its seat by spring forcealone. This maintains a low fuel pressure (pmin = 50bar) at the high pressure outlet port of the fuel pump tothe fuel rail. The fuel pressure regulator is thereforeopened.



The setpoint pressure in the fuel rail during starting mustbe at least 150 bar. Below this minimum pressure, fuelinjector needle lift is not possible. The engine cannotbe started or is stopped.

Fuel pressure regulator actuated

E53954

2

3

1

2

5

76

4

8 10

9

Fuel pressure at the high-pressure outlet port ofthe high-pressure pump

1

To the fuel return2

Valve ball3

Compression spring4

Armature5

Coil energised6

Pin7

High fuel pressure8

Valve control current9

Fuel pressure regulator characteristic curve10

The energised coil attracts the armature. The armaturetransfers the magnetic force to the valve ball via the pin.

The force with which the armature is attracted, andconsequently the pressure on the valve ball, isproportionate to the valve control current. The fuelpressure regulator closes.

In the case of maximum PWM actuation, the maximumrequired fuel pressure (depending on actuation of thefuel metering valve) is adjusted in the fuel rail.

Purpose and function (Bosch system withpiezo-controlled fuel injectors)

The structure of the fuel pressure regulator is essentiallythe same as with the previously described Siemenssystem.

Difference with respect to the Siemens system:

• A tension spring is used instead of the compressionspring.

• If the fuel pressure regulator is not actuated, thetension spring pulls the pin away from the valve ball.

• As a result, the valve ball can no longer seal the valveseat and no fuel pressure can be built up.

Effects of faults

The fuel pressure regulator operates together withthe fuel metering valve and the fuel pressure sensorin a closed loop.

If the fuel pressure regulator is defective or an electricalopen circuit occurs, adequate fuel pressure cannot bebuilt up or maintained in the fuel rail. The engine cannotbe started or is stopped.

With control faults, a limp-home program is activated.This permits restricted continuation of the journey tothe next workshop.

Diagnosis

Monitoring comprises the following checks:

• The PCM checks whether the current actuationcurrent for the fuel pressure regulator is within thesetpoint range.

• Check for short circuit and open circuit (functionsvia the current consumption at the PWM output stagein the PCM).




In the event of repairs, the fuel pressure regulator mustnot be renewed as a separate component. The entire fuelpump (Siemens system) or the entire fuel rail (Boschsystem) must always be renewed.

Fuel injectors (solenoid valve-controlled)


E70325

1

2

3

4

PCM1

Coil2

Solenoid armature3

Solenoid valve4

The fuel injectors are each equipped with a solenoidvalve. Actuation for fuel metering is carried out by thePCM.

Current is applied to the solenoid valves

• in two stages (Bosch systems)

• in three stages (Denso system)

"Two-stage" actuation of a fuel injector

E47855

1

2

3

4

Current (in A)1

Pull-in current2

Holding current3

Time4

At the beginning of an injection process, the solenoidvalve is actuated with a higher pick-up current so thatit opens quickly.

After a certain time, the pull-in current is reduced to alower holding current.

Unnecessary heat generation in the PCM is preventedin this way.

The injected fuel quantity is now determined by theopening period and the pressure in the fuel rail. Theinjection process finishes when the current supply tothe solenoid valve is interrupted and the nozzle needlecloses.



"Three-stage" actuation of a fuel injector (Denso systemonly)

1

2

3

4

E99048

5

Current (in A)1

Pull-in current2

Damping current3

Holding current4

Time5

Damping current:

• A damping current is switched between the pick-upcurrent and the holding current.

• The damping current reduces the voltage fluctuationswhen reducing the current.

Actuation currents and maximum voltagesHolding currentDamping currentPull-in currentMaximum voltageSystem

approx. 12 A-approx. 20 Aapprox. 100 VBosch

approx. 4 Aapprox. 8 Aapprox. 18 Aapprox. 120 VDensoEffects of faults

In the event of a fault, the following symptoms canoccur:

• rough engine running,


• loud combustion noise,

• reduced engine power output.

Moreover, electrical faults lead to deactivation of thesmooth-running control system (cylinder balancing) andlimited anti-slip regulation (no intervention in the enginemanagement system).

Diagnosis

The monitoring system is able to identify two types ofmalfunctions via several electrical tests:

• fuel metering fault of all fuel injectors,

• fuel metering fault of a single fuel injector.

This works by monitoring the staged power supply(current phases) of the fuel injectors (as describedpreviously).

The power consumption of the solenoid valve coil (inrelation to a defined time) indicates whether the solenoidvalve is working within its tolerances.

Deviations from the tolerance range result inuncontrolled fuel metering. This means that the injectedfuel quantity and the injection timing cannot bedetermined exactly (see Effects of faults).

In addition, the fuel injectors are checked for shortcircuit and open circuit.


The solenoid valves must not be renewed separatelyduring servicing. In the event of a fault, the entire fuelinjector must be renewed.

Each fuel injector is assigned an individual identificationnumber. After installing a new fuel injector, thisidentification number must be communicated to thePCM with the help of the IDS (see also "Lesson 2 –Fuel system", respective "Fuel injectors" section).



Fuel injectors (piezo-controlled)


E54178

1

2

3

A

B

C

D

Fuel injector closedA

Voltage pulse from the PCM: start of chargingphase, fuel injector begins to open

B

InjectionC

Voltage pulse from the PCM: start of dischargingphase, injection ends

D

PCM1

Piezo actuator2

Nozzle needle3

The piezo-electrically-controlled fuel injectors switchup to four times faster than electromagnetically-actuatedfuel injectors.

Actuation of the fuel injectors for fuel metering (startof injection and injected fuel quantity) is performeddirectly by the PCM, whereby the setpoint rail pressuremust be at least 150 bar during startup.

Fuel injector actuation characteristic curve

Characteristic curves for fuel injector actuation with pilotinjection

E54179

1

A B

4

2

3

Injected fuel quantity for pilot injectionA

Injected fuel quantity for main injectionB

Fuel injector needle lift (mm)1

Actuation current (A)2

Voltage (V)3

Crankshaft angle (CS degrees)4

A brief burst of current (charge current) is required toopen the fuel injector.

The PCM applies a charge voltage of up to approx. 140V (Siemens system) or up to approx. 160 V (Boschsystem) to the piezo element during this process.

During the charging phase, the piezo element expands(elastic tension) and opens the nozzle needle.

To contract the piezo element, a short burst of currentin the opposite direction (discharge current) isgenerated.

The discharge current causes the piezo actuator to returnto its initial position and injection ends.



Note:

• As the injection is ended by means of the dischargecurrent, the wiring harness connector of the piezofuel injector must on no account be detached whenthe engine is running.

• If the wiring harness connector is detached at themoment of injection, this leads to continuousinjection and engine damage.

Effects of faults

Rough engine running.

Increased emissions of black smoke.

Loud combustion noise (e.g. due to cut-off of the pilotinjection).

Reduced engine power output.

Moreover, electrical faults lead to deactivation of thesmooth-running control system (cylinder balancing) andlimited anti-slip regulation (no intervention in the enginemanagement system).

Diagnosis

The PCM performs various electrical checks in theindividual injector electrical circuits.

Electrical faults in the fuel injectors are detected via thepower consumption at the piezo actuator by means ofthe relevant output stage in the PCM.

The monitoring system is able to identify two types ofmalfunctions using several electrical tests:

• fuel metering fault of all fuel injectors,

• fuel metering fault of a single fuel injector.

This works by monitoring the staged power supply ofthe fuel injectors (as described previously).

The power consumption of the piezo actuator (in relationto a defined time) indicates whether the actuator isworking within its tolerances.

Deviations from the tolerance range result inuncontrolled fuel metering. This means that the injectedfuel quantity and the injection timing can no longer bedetermined precisely.

In addition, the fuel injectors are checked for shortcircuit and open circuit.

Certain faults (e.g. short to positive) lead to the fuelinjectors no longer being actuated.


The piezo elements must not be renewed separatelyduring servicing. In the event of a fault, the entire fuelinjector must be renewed.

With most systems, the fuel injectors have anidentification number or a classification. In this regard,always refer to the instructions in "Lesson 2 – Fuelsystem", relevant "Fuel injectors" section.

EGR valve


E54181

A

B

Installation position on 1.4L Duratorq-TDCi(DV) diesel engine (Emission Standard IV)

A

Installation position on 2.0L Duratorq-TDCi(DW) diesel engine

B


Electrically-controlled EGR valves are predominantlyinstalled in current diesel engines.



The EGR valve comprises the following components:

• actuator motor,

• position sensor,

• EGR valve itself.

Exhaust gas recirculation is further optimised by meansof the electrically-controlled EGR valve, which has apositive effect on exhaust gas emissions.

Illustration shows an excerpt of the circuit diagram of the2.0L Duratorq-TDCi (DW) diesel engine

E54182

4

2

1

3

1

PCM1

Actuator motor2

Electric EGR valve3

Position sensor4

The actuator motor is a DC (Direct Current) motor. Therequired opening cross section of the EGR valve isapproached by the PCM by means of PWM.

The exact position of the EGR valve is determined viathe position sensor.

It is therefore a closed loop.

With increasing operating time of the engine, residuescan start sticking to the valve seat of the EGR valve asa result of the exhaust gases flowing past. These residuescause the mechanical closing point of the EGR valve tomove.

For this reason, a cleaning/adaptation mode is activatedby the PCM each time the engine is stopped. Duringthis process, the EGR valve is moved from fully opento fully closed position, and therefore the "closing point"is redefined each time.

Effects of faults

In the event of a fault, controlled exhaust gasrecirculation is no longer possible and the EGR systemis switched off. If the EGR sticks open, this is detectedby the position sensor and the PCM then reduces thequantity of fuel injected and thus engine performance.

Diagnosis

Monitoring of the EGR actuator motor is divided intothree monitoring operations:

• monitoring of the actuator motor,

• monitoring of the position sensor,

• monitoring of the EGR valve.

In addition, the entire EGR system (interaction betweenthe EGR valve, position sensor, actuator motor and MAFsensor) is monitored under certain operating conditions.

The actuator motor is monitored for the following:

• power consumption of the actuator motor(excessively high or low current flow through thecoil),

• EGR valve cleaning diagnosis.

The power consumption of the coil is used as a basisto check whether the signal from the PCM is within thelimits. Moreover, potential overheating of the EGRvalve is detected via the resistance of the coil.

Cleaning diagnosis is also performed via the powerconsumption of the actuator motor. During cleaning,the actuator motor must open and close the EGR valvewithin a defined timeframe. A stuck EGR valve isdetected via the current consumption of the actuatormotor.

Note: Cleaning/adaptation mode can be observed withthe help of a IDS datalogger.



The position sensor is monitored for the following:

• limit range check: detects short and open circuits,

• logical rise/fall time of the signal: determinesintermittent errors (e.g. loose contact for a plug),.

• plausibility check: detects a seized or sticking EGRvalve.

The plausibility check is started when a certain enginespeed is reached.

If a specific control deviation with regard to thecalibrated values is detected during the check, this isinterpreted as a fault by the PCM and a relevant DTCis stored.


If a new EGR valve is installed or the PCM isrenewed/reprogrammed, the EGR valve must beinitialised by the PCM via the IDS.

Wastegate control valve(vacuum-controlled systems)


Illustration shows the 2.0L Duratorq-TDCi (DW) dieselengine in the 2006.5 S-MAX/Galaxy

2 12 1E98158

Wastegate control valve1


The valve is installed at the cylinder block or at thecylinder head.


The wastegate control valve is provided with vacuumby the vacuum pump.

Pulse width modulated signals from the PCM controlthis vacuum via the wastegate control valve.

The controlled vacuum acts on the vacuum actuator inthe variable-geometry turbocharger.

Effects of faults

In the event of a fault, boost pressure control is no longerpossible. Therefore, the injected fuel quantity is limited(power output reduction) and the EGR system isdeactivated.

Diagnosis

Boost pressure control operates in a closed loop. Theadjustment of the guide vanes of the variable geometryturbocharger is carried out via the wastegate controlvalve. The boost pressure is controlled depending onrequirements via the MAP sensor.

Monitoring of the wastegate control valve comprisesthe following checks:

• short circuit (to ground and positive) and opencircuit,

• intermittent faults (e.g. loose contact).

Furthermore, wastegate control valve or vacuum systemfaults are detected by the MAP sensor.

Wastegate control valve faults are detected by the outputstage in the PCM via the power consumption of thewastegate control valve.

As the EGR system is deactivated, the NOX emissionsincrease sharply. As a result, exhaust gas limits areexceeded.



Intake manifold flap and intakemanifold flap solenoid valve(vacuum-controlled systems)


E54180

1 23

5

4

Air flow in intake manifold1


PCM3


Vacuum actuator5

The solenoid valve is installed at the cylinder block orat the cylinder head.


In some versions, a vacuum-controlled intake manifoldflap is used, which is actuated via an intake manifoldflap solenoid valve.

The intake manifold flap has the following functions:

• preventing "serious engine judder" when the engineis stopped,

• closing the air channel through the charge air cooler(vehicles with fuel additive diesel particulatefilter),

• restricting the intake air to improve the EGR rate(certain versions only),

• restricting the intake air to assist the increase inexhaust gas temperature during the active DPFregeneration process (see also "Lesson 6 – Engineemission control").

Preventing serious engine judder when the engine isstopped:

• Diesel engines have a high compression ratio. Thehigh compression pressure of the intake air affectsthe crankshaft via the pistons and connecting rodsand causes judder when the engine is stopped.

• The intake manifold flap solenoid valve connectsthe vacuum for the intake manifold flap vacuumactuator, as a result of which the intake manifoldflap is closed. This prevents engine judder when theengine is stopped.

• The intake manifold flap solenoid valve is energisedwhen the engine is stopped. The vacuum foractuation of the intake manifold flap vacuum actuatoris activated and the intake manifold flap is closedbriefly.

Closing the air channel through the charge air cooler(vehicles with fuel additive diesel particulate filter):

• This function is utilised when the exhaust gastemperatures are low in vehicles with dieselparticulate filters. The intake manifold flap closesthe air channel through the charge air cooler at thesame time as the charge air cooler bypass is opened(see also "Lesson 6 – Engine emission control").

Restricting the intake air to improve the EGRrate (certain vehicles with Emission StandardIV)

With certain vehicles, the normal exhaust gasrecirculation is not adequate to return the required EGRrate.

By slightly restricting the intake air using an intakemanifold flap, a vacuum is created in the intake tract.This vacuum increases the EGR flow.



Effects of faults

In the event of a signal failure or a failure of the intakemanifold flap solenoid valve:

• the intake manifold flap remains open when theengine is stopped. This results in increased enginejudder when the engine is stopped,

• controlled exhaust gas recirculation is only possibleto a limited extent (certain versions only),

• the regeneration of the diesel particulate filtercannot be performed in an ideal way under certainconditions.

Diagnosis

The solenoid valve is checked for short circuit and opencircuit.

Intake manifold flap actuator motor(1.6L Duratorq-TDCi (DV) diesel engine,Emission Standard IV)


E513731

2


Charge air cooler bypass flap (vehicles with DPFonly)

2

The actuator motor is located directly at the intakemanifold flap housing. The intake manifold flap housingis flange-mounted to the intake manifold.


The intake manifold flap takes charge of the followingfunctions:

• restricting the intake air for exhaust gas recirculation,

• closing the intake system when the engine is stopped,

• closing the air path via the charge air cooler whilethe regeneration of the diesel particulate filter takesplace (see also "Lesson 6 - Engine emission control",section "DPF with fuel additive system").

The intake manifold flap is operated by an actuatormotor. The actuator motor is a DC motor that preciselyapproaches the requested position of the intake manifoldflap through actuation by the PCM.

The actuator motor also contains a position sensor. Theposition sensor informs the PCM precisely of theinstantaneous position of the intake manifold flap.

In order to restrict the intake air flow, the intakemanifold flap is closed by a set angle depending onrequirements.

This produces a vacuum behind the intake manifoldflap. The vacuum enables the exhaust gases from theopen EGR valve to be fed more efficiently to the freshair flow.

Advantage: A higher EGR rate can be fed to thecombustion chambers of the engine. This further reducesthe NOX emissions.



E51375

2

2

4

1

3

5

Voltage supply from the battery junction box1

PCM2

DC motor3

Actuator motor4

Position sensor5

When the engine is stopped, the intake manifold flapis closed. This prevents intake air from being drawn inand, consequently, running on (judder) of the engine.

In the case of vehicles with a diesel particulate filter,the intake air temperature has to be increased undercertain operating conditions for the regeneration process.

To achieve this, the intake manifold flap is closeddepending on requirements and a charge air coolerbypass opened (bypass of the charge air cooler) – see"Lesson 4 – Engine emission control".

Effects of faults

The intake manifold flap is sticking in the open position:

• EGR is limited or switched off,

• when stopping the engine, increased engine judderoccurs.

The intake manifold flap is sticking in the closedposition:

• engine does not start.

If the intake manifold flap is sticking, only limitedcontrol of exhaust gas recirculation is possible.Depending on the position in which it is sticking, toomuch exhaust gas could be recirculated under certainload conditions. In this case, the injected fuel quantityand therefore the engine's power output is reduced toprevent black smoke.

Serious faults in the position sensor will result in theEGR system being deactivated.

Diagnosis

Monitoring the intake manifold flap (by means of theposition sensor) includes the following checks:

• limit range check,

• plausibility check,

• control deviations,

• sticking intake manifold flap.

Most faults will result in limited exhaust gasrecirculation or the EGR system being shut off.



Turbocharger variable vane electricalactuator


1

2

1

2

E97183


TC2

The electrical actuator is mounted directly at the TC.


Current diesel engines have a variable-geometryturbocharger that is actuated via an electrical actuator.

Its exact positioning for each operating state is achievedby the electrical adjustment of the guide vanes. This hasa positive effect on exhaust emissions and helps toachieve legally prescribed exhaust emission levels.

E46463

1

A B

2

3

4

5

6

7

Adjuster mechanismA

Control electronicsB

Actuator motor (DC motor)1

Actuator motor contact block2



Inductive sensor unit3

Halfshaft4

Worm gear5

Drive pinion6

Actuator motor contacts7

The electrical actuator consists of the followingcomponents:

• actuator motor,

• position sensor,

• control unit.

The actuator motor (DC motor) in the actuator actuatesthe halfshaft via a worm gear.

The halfshaft is connected to the guide vanes by theactuating lever. When the lever is actuated, the guidevanes are adjusted.

There is an inductive position sensor at the end of thehalfshaft. When the halfshaft is turned, a sinusoidalsignal is generated inductively here. The electronics inthe control unit convert the sinusoidal signal into aPWM signal. The number of square-wave signalsprovides exact information on the current angularposition of the guide vanes.

The control unit actuates the actuator motor. Thisactuation, depending on the type of actuation by thePCM, is more or less complex.

Types of actuation by the PCM:

• actuation via a separate line,

• complete regulation by the PCM.

NOTE: The type of actuation for the respective vehiclecan be found in the wiring diagrams in the currentService Literature.

Actuation via a separate line

E62584

2

1


PCM2

The PCM actuates the actuator via a separate line bymeans of PWM signals.

The actuator control unit then actuates the actuatormotor accordingly.

The position sensor detects the current position of theguide vanes and communicates this position to theactuator control unit.

The control unit compares the PCM input parameterswith the position sensor parameters and corrects theguide vane position if necessary.



Complete regulation by the PCM

E70323

Connection 1: Actuator motor (+)1

Connection 2: Actuator motor (–)2

Connection 3: Position sensor (–)3

Connection 4: Position sensor PWM outputsignal

4

Connection 5: Position sensor reference voltage5

PCM6

Actuator motor7

Position sensor (contactless)8


NOTE: The exact pin assignment for the plugconnections can vary from vehicle to vehicle and youshould always refer to the current Service Literature.

In this system, a simplified electrical actuator is used.

The control unit in the actuator is no longer required.Only integrated electronics convert the sinusoidal signalof the position sensor into a PWM signal.

This means:

• the actuator motor is actuated directly by the PCM,

• the position of the guide vanes is detected directlyby the PCM via the position sensor.

The inductive (contactless) position sensor transmitsPWM signals to the PCM. The duty cycle is determinedby the position of the guide vanes.

Duty cycle of the position sensor:

• with minimum opening of the guide vanes(maximum boost pressure): approx. 90 %

• with maximum opening of the guide vanes(minimum boost pressure): approx. 10 %

Effects of faults

If the actuator malfunctions, boost pressure control isno longer possible. In this case, the engine output isrestricted by means of a reduction in the injected fuelquantity.

An implausible boost pressure is detected by the MAPsensor, and the actuator then sets the guide vanes to thefully open position.

In the event of a fault, the EGR system is switched off.

Diagnosis

The monitoring system of the actuator consists of directand indirect monitoring.

Direct monitoring:

• Monitoring of the PCM/actuator lines for shortcircuits to ground and positive.

• Actuation of the actuator via a separate line:

– Integrated diagnosis in the control electronicsof the actuator detects malfunctions in theactuator and PWM as well as voltage supplyoutside the standard range.

• Complete regulation by the PCM:

– Integrated diagnosis in the PCM detectsmalfunctions in the actuator and the positionsensor as well as voltage supply outside thestandard range.

Indirect monitoring:

• Indirect monitoring is performed via the MAP sensor.In the process, the engine management system checkswhether the currently required boost pressure isactually being provided.

• An open circuit (open loop) in the signal wire fromthe PCM to the actuator cannot be detected by thePCM. However, an open circuit leads to animplausible boost pressure which then results in theguide vanes of the turbocharger being set in the fullyopen position (minimal boost pressure). The pressuredeviation is detected by the MAP sensor and arelevant DTC is set.


The TC and the electrical actuator form a unit. Theelectrical actuator must not be renewed separately duringservicing.



Electric fuel pump (2.2L Duratorq-TDCi(DW) diesel engine only)


21

4

3

21

4

3

E96135

Fuel return line1

Fuel feed line2

Electric fuel pump3

Swirl pot4

NOTE: The purpose of the electric fuel pump in thefuel pump and sender unit is not to deliver fuel to thecommon rail fuel pump.

The fuel filter features a bypass-controlled fuelpreheater. With cold fuel, the majority of the returningfuel is returned directly to the fuel filter and thereforethe fuel feed.

The fuel returning to the fuel tank helps to adequatelyfill the swirl pot.

If there is insufficient fuel returning, there may not beenough fuel in the swirl pot of the fuel pump and senderunit.

As a result, the common rail system could take in airwhen cornering. The air taken in could cause majordamage to the injection system.

The electric fuel pump draws only fuel from the fuelpump and therefore assists with filling of the swirl pot.

The electric fuel pump is activated around 5 secondsafter the engine starts by the PCM. The pump isdeactivated again when the engine is stopped.




1. Which of the following statements about the fuel metering valve is incorrect?

a. It controls the fuel feed to the high-pressure chambers of the fuel pump.

b. It is actuated by means of PWM signals by the PCM.

c. The larger the cross section of the opening, the greater the fuel pressure delivered by the fuel pump.

d. The valve is always open when de-energised in all systems.

2. Which common rail systems are equipped with a fuel pressure regulator?

a. Only Siemens systems with piezo-controlled fuel injectors.

b. Only Bosch systems with piezo-controlled fuel injectors.

c. Only systems with piezo-controlled fuel injectors.

d. Only systems with solenoid valve-controlled fuel injectors.

3. Why do piezo-controlled fuel injectors require a "discharge voltage"?

a. To end fuel injection.

b. To open the fuel injectors.

c. To protect the piezo elements from excessive voltage peaks.

d. To protect the output stage in the PCM from excessive voltage peaks.

4. The EGR valve comprises which components?

a. EGR valve and position sensor

b. EGR valve and actuator motor

c. Actuator motor, position sensor and EGR valve

d. Actuator motor, position sensor, EGR valve and EGR control unit


Test questionsLesson 5 – Actuators

Pollutant emissions reduction

Maximum exhaust emission levels for passenger vehicles in grams per kilometre (g/km)Particulate

matter (PM) (g/km)

HC + NOXNOX (g/km)HC (g/km)CO (g/km)

0.050.560.50-0.64EmissionStandard III

0.0250.300.25-0.50EmissionStandard IV

0.18-1.200.403.20EOBD limits

In order to meet the increasingly stringent emissionstandards, exhaust gas aftertreatment will increase insignificance even for diesel engines, despite the progressmade with regard to engine modifications.

By constantly improving the injection systems (directinjection in conjunction with constantly increasinginjection pressures) and their electronic control, theperformance, economy and comfort of the diesel enginehave steadily been increased.

Also of significance is the reduction of exhaust gasemissions, the maximum levels of which have to becontinuously improved due to legal requirements.

The oxidation catalytic converter, in some for someyears now, was the first step towards exhaust gasaftertreatment. It significantly reduced HC and COemissions.

The measures inside the engine (high injectionpressures, nozzle design, timed introduction of fuel andcombustion chamber shape) have once more loweredthe CO, HC and diesel particulate emissions.

The NOX emissions produced by excess air in dieselcombustion are more and more effectively reduced byexhaust gas recirculation systems which are constantlybeing improved.

Diesel particulate matter

As already mentioned, a considerable reduction in dieselparticulate matter has been achieved by modificationsto the engine.

Since the first emission standard for diesel passengercars was introduced by the EU Commission in 1989,the limit for particulate matter has now been reducedby a factor of 44 from 1.1 g/km to only 0.025 g/km(Emission Standard IV).

With regard to the imminent Emission Standard V(0.005 g/km) it is becoming clear, however, that themeans by which diesel particulate emissions can bereduced through engine modifications have beenvirtually exhausted.

A further incentive for achieving a reduction isincreasing environmental awareness and the fact thatthe residual diesel particulate matter has a harmful effecton the human body.

Diesel particulates are composed mainly of a chain ofcarbon particles (soot) with a very large specific surfacearea.

The noxious effect of diesel particulate matter is a resultof adsorption of unburned or partially burned HC. Inaddition, fuel and lubricant oil aerosols (solid or liquidsubstances finely distributed in gases) and sulphates(depending on the sulphur content of the fuel) bind withthe soot.

DPF (general)

The use of a DPF enables the diesel particulates stillemitted today to be efficiently removed from the exhaustgas.

By using appropriate filter materials it is possible toretain more than 95% of the diesel particulates in theDPF.

With this method almost all of the particulates can beretained, however the complete removal of dieselparticulates using conventional catalytic methods is notpossible. The diesel particulates are deposited in theDPF.


Lesson 6 – Engine Emission ControlIntroduction

How the DPF works

E54231

Exhaust gas from the engine1


Filtered exhaust gas3

DPF4

Catalytically cleaned exhaust gas5

The DPF has a honeycomb structure, the walls of whichare made of porous silicon carbide. In addition, theindividual channels are sealed at one side and offset toeach other.

After combustion has occurred, some diesel particulatesmay still be present in the exhaust gas. As part of thefiltration process, the exhaust gases loaded with dieselparticulate matter flow into the DPF and are then forcedto flow through the porous walls as a result of the offsetposition of the sealed channels.

The build up of diesel particulate matter in theintermediate chambers of the porous walls increases thefiltration effect still further.

The DPF is always downstream of the oxidationcatalytic converter.

Regeneration of the DPF (general)

As the collection capacity of the DPF is only limited, ithas to be regenerated at regular intervals.

Regeneration means burning off the deposited dieselparticulates in the DPF.

An exhaust gas temperature of at least 550 to 600 °C isrequired for burning off the deposited diesel particulates.In this temperature range, the carbon content of thediesel particulates oxidises with the O2 content presentin the exhaust gas to form harmless CO2 (CarbonDioxide).

Such high exhaust gas temperatures are rarely attained,however, during actual driving. The average exhaustgas temperature for the average driving style is approx.270 °C.


IntroductionLesson 6 – Engine Emission Control

In order to nevertheless attain the necessary exhaust gastemperature, different measures must be taken dependingon the current exhaust gas temperature.

Intervention in the engine management system

During regeneration, comprehensive control loops areactivated in the engine management system dependingon different temperatures and pressures.

To attain the necessary temperature for regeneration,different operations are performed (e.g. throttling theintake air, post-injections, reducing the boost pressure).

These operations serve to raise the exhaust gastemperature while keeping the added fuel consumptionas low as possible.

Fuel additive system

By adding a fuel additive to the fuel tank, the burn-offtemperature of the diesel particulates can be loweredby 100 °C to approx. 450 to 500 °C.

However even these exhaust gas temperatures are notalways attained during average driving. Theinterventions by the engine management system are,however, less severe than without the use of fueladditive.

Coated DPF

The filter material of this DPF is coated with a preciousmetal. This precious metal coating helps to convert thediesel particulates catalytically at a temperature of 300to 450 °C (passive regeneration).

However, it is often not possible to attain temperaturesthis high in urban traffic. In this case, the dieselparticulates are deposited in the DPF. To burn them off,active regeneration must be initiated at regular intervalsby means of intervention in the engine managementsystem.


Lesson 6 – Engine Emission ControlIntroduction

Component overview

DPF system in the 1.6L Duratorq-TDCi (DV) diesel engine

1 2

3

13

9

1112

6

5

4

10

E48490

7

8

Catalytic converter exhaust gas temperaturesensor

1

Catalytic converter2

DPF differential pressure sensor3

PCM4

Fuel additive control unit5

Instrument cluster6

Tank flap switch7

Tank flap solenoid8

Fuel additive tank9

Fuel additive pump unit10

Injector11


DPF with fuel additive systemLesson 6 – Engine Emission Control

Fuel tank12 DPF13

DPF system in the 2.0L Duratorq-TDCi (DW) diesel engine

9

10

1112

65

E48491

13

4

14

2

13

7

8


1

DPF exhaust gas temperature sensor2

DPF3

Pipes to the DPF differential pressure sensor4

Instrument cluster5


Tank flap switch7

Tank flap solenoid8

Fuel additive tank9


Injector11


Lesson 6 – Engine Emission ControlDPF with fuel additive system

Fuel tank12 PCM13


DPF

A B

12

c

d

1

2A B

12

c

d

1

2

E97467

DPF/oxidation catalytic converter unit in the1.6L Duratorq-TDCi (DV) diesel engine

A

DPF in the 2.0L Duratorq-TDCi (DW) dieselengine

B

Exhaust gas temperature sensor1

Pipes to the DPF differential pressure sensor2

Oxidation catalytic converterc

DPFd

DPF of the 1.6L Duratorq-TDCi (DV) engine:

• The DPF is located downstream of the catalyticconverter in the flow direction of the exhaust gases.

• The oxidation catalytic converter and DPF arecombined in one housing.

DPF of the 2.0L Duratorq-TDCi (DW) engine:

• The DPF is contained in a separate housing,downstream of the oxidation catalytic converter.

The diesel particulates contained in the exhaust gas aredeposited in the DPF. The pressure drop across the DPF(measured via the DPF differential pressure sensor) isan indicator for the soot load of the filter.

The soot load capacity of the DPF is limited, however,so that it has to be regenerated at regular intervals(burning of the diesel particulates).

After regeneration, ash residues that have formed fromthe fuel additive, engine oil and fuel remain in the DPF.These constituents cannot be further converted and canonly be deposited in the DPF up to a certain degree.

This means that the DPF must be renewed at prescribedservice intervals (see the current Service Literature).



Charge air cooler bypass

System in the 1.6L Duratorq-TDCi (DV) diesel engine

E51462

1

23 4

57

8

9

6

10

MAP sensor1

Intake manifold flap housing2

Charge air cooler bypass3

Combined IAT and MAF sensor4

Connecting piece between turbocharger andcharge air cooler

5

Charge air cooler6

Turbocharger vacuum actuator7

Charge air cooler bypass flap actuator motor8

Connecting piece between charge air cooler andintake manifold flap

9

Intake manifold flap actuator motor10



System in the 2.0L Duratorq-TDCi (DW) diesel engine

E54232

Connecting piece between air cleaner housingand turbocharger

1

Combined IAT and MAF sensor2

Charge air cooler3

Connecting piece between turbocharger andcharge air cooler

4

Charge air cooler bypass5

Charge air cooler bypass flap vacuum actuator6

Intake manifold flap housing7

Turbocharger8

Intake manifold flap vacuum actuator9

Connecting piece between charge air cooler andintake manifold flap housing

10



An intake manifold flap housing has been added to theintake system in conjunction with the DPF system. Theintake manifold flap housing contains the followingcomponents:

• charge air cooler bypass flap,

• intake manifold flap,

• MAP sensor,

• IAT sensor (not illustrated).

The intake manifold flap creates the connectionbetween the cooled air from the charge air cooler andthe intake ducts of the engine via the intake manifoldflap housing.

The charge air cooler bypass flap creates a directconnection between the compressor side of theturbocharger and the intake ducts of the engine via the

intake manifold flap housing. The charge air cooler isbypassed. The charge air cooler bypass flap is onlyadjusted during the regeneration phase.

During the regeneration phase, the air mass flowingthrough the charge air cooler (regulated by the intakemanifold flap) is reduced.

At the same time, the flow of uncooled air mass via thecharge air cooler bypass (regulated by the charge aircooler bypass flap) is increased.

This reduces the engine's cylinder charge while keepingthe intake air temperatures constant. Variations inexhaust gas temperatures are thereby prevented duringregeneration.

The position of both flaps is dependent on the intake airtemperature. For this reason, there is an additional IATsensor at the intake manifold flap housing, downstreamof the intake manifold flap and charge air cooler bypassflap.

Fuel additive system – general

E51469

1 2 3

4

56

Fuel tank1

Hoses for fuel additive (top up and ventilation)2

Fuel additive tank3




Fuel additive line to the injector5 Injector6

The fuel additive system comprises the followingcomponents:

• a fuel additive tank with a fuel additive pump unit,

• fuel additive lines,

• an injector.

In addition, a tank flap switch and a fuel additive controlunit are installed in the vehicle (not illustrated).

The fuel additive is injected into the fuel tank via thefuel additive pump unit, the fuel additive line and theinjector.

The fuel additive mixes with the diesel fuel in the fueltank. The quantity of the fuel additive to be injected isdependent on the diesel fuel quantity at each refuelling.

Components of the fuel additive system

Fuel additive

Metallic catalysts, cerium and iron, are used as fueladditives. These accelerate burn-off of the dieselparticulates and lower the temperature at which burn-offcan occur.

Each time after the fuel tank is filled, a metered quantityof fuel additive is injected into the fuel tank where itmixes with the fuel.

When combustion takes place, the cerium and iron tracesmix with the particulates from the diesel exhaust gasand provide for a considerably lower burn-offtemperature.

As a result, the particulate matter collected in the filtercan be burned off at temperatures of just over 450 °C.

The homogeneously bound cerium oxide/dieselparticulate matter is then filtered out by the DPF, whereit becomes embedded.

Thanks to the combination of fuel additive (reductionin the burn-off temperature of the particles) and theengine management system (increase in the exhaust gastemperature), the DPF can be regenerated not only underfull load conditions, but also in the partial load range atcomparatively low exhaust gas temperatures typical forurban traffic.

Fuel additive tank

E48498

1

5

2

3

4

6

Fuel line to the fuel tank1

Overflow (when filling)2

Fuel filler connection3

Fuel additive tank4


Vent assembly6

The fuel additive tank is located behind the fuel tankand is attached to the crossmember. The fuel additivetank forms a unit together with the fuel additive pumpunit and can therefore only be renewed as a whole.

The fuel additive tank has a capacity of 1.8 litres for anaverage total mileage of 60,000 km. Therefore, the fueladditive has to be topped up according to the servicespecifications.

Note: The fuel additive tank cannot be emptied fully.Once the quantity remaining falls below 0.3 litres, fueladditive injection ceases (the driver is informed beforethis occurs by means of the relevant warning indicators).The residual quantity prevents the fuel additive pumpfrom drawing in air, which could result in incorrectquantities of fuel additive being metered.

The maximum top-up quantity is therefore 1.5 litres.



Fuel additive pump unit

E48499

3

21

Connection to the fuel tank1

Fuel additive pump2

Piezo sensor3

The fuel additive pump unit is designed as adisplacement-type pump (piston pump). It feeds the fueladditive, metered according to the command issued bythe fuel additive control unit, via a short fuel line to theinjector where it is injected into the fuel tank.

The piezo sensor at the bottom end of the fuel additivepump unit contains two sensor elements with thefollowing functions:

• They determine changes in the viscosity of the fueladditive as a result of changes in ambienttemperature.

• They detect when the fuel additive tank is empty(measurement of the precise fuel level in the fueladditive tank is also envisaged and will beimplemented at a later date).

In the event of an empty fuel additive tank, initially theengine system fault warning indicator illuminates. Thismeans that from this point, only a residual quantity offuel additive is available for approximately 250 litresof fuel. If the fuel additive tank is not refilled, the MILilluminates and the fuel additive injection process isstopped.


• The fuel additive pump unit is part of the fueladditive tank and must not be renewed separatelyduring servicing.

Injector

E48500

The injector is connected to the fuel additive tank bymeans of a fuel line.

The fuel additive pump generates pressure in the fuelline. The injector non-return valve opens and fueladditive is fed into the fuel tank.



Component overview – system control

Components of the Bosch system

E70769

1

2

3

4

5

6

7

8 9

10

11

12



IAT sensor3

Tank flap switch and solenoid (in the tank flap)4

Piezo sensor on the fuel additive pump unit5


PCM7

CAN8

DLC9



Fuel additive pump12



Components of the Siemens system

E70774


1



IAT sensor4

Tank flap switch and solenoid (in the tank flap)5

Piezo sensor on the fuel additive pump unit6


PCM8

CAN9

DLC10

Charge air cooler bypass flap solenoid valve11


Fuel additive pump13



PCM

During the regeneration phase, the PCM partiallyassumes control of the system.

During the regeneration phase, completely differentparameters are required for engine management. Forthis reason, the PCM is equipped with an additional dataset for the regeneration phase.

The fuel additive system is monitored by a separate fueladditive control unit which communicates with the PCMvia the CAN data bus.

The PCM and the fuel additive control unit can bediagnosed by means of the WDS via the DLCconnection.


When installing a new PCM or before loading newsoftware as well as when installing a new DPF, alwaysread the instructions in the current Service Literature.

Fuel additive control unit


E48493

1


The fuel additive control unit is located under theright-hand rear seat.


A separate fuel additive control unit is responsible forfuel additive injection. It is connected to the PCM viathe CAN data bus.

The fuel additive control unit detects when the vehiclehas been refuelled on the basis of various input variablesand subsequently controls metering of the fuel tankadditives to be injected into the fuel tank.

The fuel additive control unit also features a counterfunction. Using this counter, the fuel additive controlunit calculates the level in the fuel additive tank byrecording the frequency with which the fuel additivepump unit is actuated and the duration of theseactuations.



As soon as the level in the fuel additive tank dropsbelow a specific, calculated quantity remaining, theengine system fault warning indicator in theinstrument cluster is actuated, indicating in this casethat the quantity of fuel additive remaining is sufficientfor approximately 250 litres of fuel.

This means that in the case of a fuel tank with a capacityof 50 litres, sufficient fuel additive remains availablefor approximately five complete refuelling operationsor, for example, for ten refuelling operations at 25 litreseach.

Information concerning the actual quantity of fuel addedis sent by the fuel level sensor. With a properlyfunctioning system, a minimum tank quantity of 5 litresis registered.

If the engine system fault warning indicator illuminates,this is a signal to the driver that they should drive to thenearest Authorised Ford Workshop as soon as possible.

If the driver does not do this, the MIL is set when thefuel additive tank has been emptied completely.

To indicate an empty fuel additive tank, the fuel additivecontrol unit sends the appropriate information via theCAN bus to the PCM, which logs a DTC and, in turn,actuates the corresponding indicator in the instrumentcluster, also via the CAN bus.

Note: If one of the previously mentioned lampsilluminates to indicate that the fuel additive tank isempty, the corresponding DTC must be cleared in thefault memory by means of the WDS once the fueladditive tank has been refilled. In addition, the countermust be reset with the help of the IDS.

Note: The fuel additive tank cannot be emptied fully.Once the quantity remaining falls below 0.3 litres, fueladditive injection ceases (the driver is informed beforethis occurs by means of the relevant warning indicators).The residual quantity prevents the fuel additive pumpfrom drawing in air, which could result in incorrectquantities of fuel additive being metered.

Effects of faults

If a damaged fuel additive control unit means that fueladditive can no longer be added to the fuel, then theDPF can no longer be systematically regenerated. Theresult is a blocked DPF.

Diagnosis

The fuel additive system is a stand-alone systemcontrolled by the fuel additive control unit.

The fuel additive control unit detects faults in the fueladditive system and sends these via the CAN bus.

The PCM registers the CAN fault data from the fueladditive control unit and subsequently logs acorresponding DTC.

Faults in the fuel additive system can lead toillumination of both the engine system fault warningindicator and the MIL.

In the event of CAN communication failure, the MILis also actuated.

Possible fault codes: P2584, P2585, U0118

Fuel additive pump unit

Function

E48499

3

21

Connection to the fuel tank1

Fuel additive pump2

Piezo sensor3

The fuel additive pump unit consists of the fuel additivepump and a two-piece piezo sensor.

The internal piezo sensor can only detect when thefuel additive tank is empty. In conjunction with thecounter of the fuel additive control unit, this devicetherefore makes doubly sure that an empty fuel additivetank can be detected.

Note: There are plans to enable the external piezo sensorto detect the precise level and these will be implementedat a later date.



The external piezo sensor establishes the changingviscosity of the fuel additive affected by the ambienttemperature and sends this reference value to the fueladditive control unit.

On the basis of this input signal, the fuel additive controlunit is able to precisely determine the injection time forthe fuel additive.

The fuel additive pump is actuated by the fuel additivecontrol unit using pulse width modulation and suppliesthe injector on the fuel tank with a precise quantity offuel additive due to its defined stroke.

Tank flap switch


E51571

1

2

Solenoid (in the tank flap)1

Tank flap switch (reed contact)2

The tank flap switch is incorporated into the fuel tankfiller shroud. The actuating solenoid is located in abracket at the tank flap.


The tank flap switch is designed as a reed contact andinforms the fuel additive control unit when the fuel tankis filled.

However, the fuel additive control unit only registersthat refuelling has taken place if detected by the fuellevel sensor in addition to the tank flap switch signaland if the vehicle speed is less than 3 km/h.

If a clear signal is received from the tank flap switch asa result of opening and closing the tank flap and if anincrease in the fuel quantity (differential quantity) of atleast 5 litres is detected in the fuel tank once the ignitionhas been turned on, the fuel additive control unitassumes that refuelling has taken place.

The fuel additive control unit calculates the fuel additivequantity to be injected according to the differentialquantity calculated, and activates the fuel additive pump.

Activation/metering is performed as soon as the vehicleexceeds a speed of 40 km/h or, if this speed is notreached, 4 minutes after the engine is first started.

Note: After the fuel additive tank has been filled (aspart of a scheduled service), the counter in the fueladditive control unit must be reset. It can be reset byopening and closing the tank flap in a certain way anduse should be made of this feature (see the currentService Literature). Resetting the counter via the tankflap switch is not possible if either the engine systemfault warning indicator or the MIL has illuminated as aresult of the fuel additive tank becoming empty. In thiscase, the counter must be reset with the help of the IDS.

When the tank flap is closed, the tank flap switch isopen.

Effects of faults

If the signal from the tank flap switch fails, smallrefuelling quantities (below 10 litres) cannot be detected.

The software in the fuel additive control unit has beendesigned to only allow fuel additive to be injected inthe case of a missing signal from the tank flap switchif the refuelling quantity is at least 10 litres.

The reason for this is that, in the worst case scenario,the vehicle may, for example, have been rolled onto aslope with the "ignition OFF". Then, when the ignitionis next switched on, the fuel additive control unit couldregister an increased quantity of fuel via the fuel levelsensor and might misinterpret this as a refuellingoperation. To prevent fuel additive from being injectedunnecessarily, if the tank flap switch is faulty the fuellevel difference is increased from at least 5 litres to aminimum of 10 litres.

If the signal fails, the engine system fault warningindicator is actuated.



Exhaust gas temperature sensor(s)


E48497

The Bosch system

• has just one exhaust gas temperature sensor. This islocated directly in the oxidation catalyticconverter/DPF unit upstream of the DPF.

The Siemens system

• has a catalytic converter exhaust gas temperaturesensor and a diesel particulate filter exhaust gastemperature sensor.


The exhaust gas temperature of at least 450 °C to 550°C required for burning off the diesel particulates isdetected by the sensor(s) and transmitted to the PCM.

The exhaust gas temperature input variable is used forcalculation purposes by the PCM, which also takes otherparameters into account.

Depending on the exhaust gas temperature calculated,the PCM decides whether or not the regeneration processcan be initiated.

Through the arrangement of the two sensors, the exhaustgas temperature required for regeneration can beadjusted and monitored very precisely.

The regeneration process cannot be terminated unlessa minimum temperature of 450 °C is reached andmaintained.

Effects of faults

Bosch system:

• In the event of a fault, the PCM reverts to a substitutevalue. The substitute value is calculated on the basisof:

– coolant temperature,

– engine speed,

– engine load.

Siemens system:

• If a fault occurs in one of the two sensors, the valueof the other exhaust gas temperature sensor is usedby the PCM.

• If both the sensors are defective, a substitute valueis calculated.

Diagnosis

The following checks are carried out:

• short and open circuit (by means of a limit rangecheck),

• logical rise/fall rate of the signal, by which meansintermittent errors (e.g. loose connector contact) aredetermined,

• plausibility (after engine start-up, a certaintemperature increase is expected by the PCM withina certain period).

A faulty sensor has no direct influence on exhaustemissions. As regeneration is, however, significantlyimpaired and clogging of the DPF is possible, the MILis set in the event of a fault.



DPF differential pressure sensor


E59691

The differential pressure sensor is located in the enginecompartment, near the bulkhead.


The sensor measures the current exhaust gas pressureupstream and downstream of the DPF and determinesthe differential pressure based on the readings.

For this purpose there is a pipe connection upstreamand downstream of the DPF.

The readings are converted by the sensor into a voltagesignal and transmitted to the PCM.

The soot particles and ash collected in the DPF resultin a change in pressure in the exhaust gas streamupstream and downstream of the DPF. The change inpressure is used by the PCM as an input variable fordetermining the soot load.

If the measured value exceeds the programmedmaximum value, regeneration of the DPF is initiated,taking into account the necessary boundary conditions.

In addition, the sensor is also used for diagnosing thecondition of the DPF.

Effects of faults

In the event of a fault, the PCM reduces the enginepower output by reducing the injected fuel quantity.

Diagnosis

The monitoring system performs the following checksvia the sensor:


• DPF efficiency,

• DPF overloaded,

• DPF blocked,

• monitoring of the maximum regeneration attemptsin the lower load range.

The plausibility check is divided into two tests:

• With the engine running: The differential pressureis measured via the DPF. This is determinedaccording to the difference between the anticipatedpressure of the exhaust gas stream as calculated bythe PCM and the actual pressure of the exhaust gasstream before and after it passes through the DPF.This test is performed under certain operatingconditions (depending on coolant temperature, enginespeed and engine load – regeneration not activated).Assuming that these conditions are met, the sensorsignal must be within the specified limits.

• With the engine switched off: Here, the differentialpressure is measured before the engine is started orimmediately after it has been switched off. If thedifferential pressure calculated via the DPF is greaterthan the value specified by the PCM, this isrecognised as an implausibility.

The DPF efficiency test determines whether the filtermaterial in the DPF is in sound condition.

The DPF element itself poses a certain resistance to theexhaust gas stream that is calculated by the PCM. Toachieve the calculated exhaust gas stream, the test isperformed under certain operating conditions.

If the value measured here is below the minimum valuecalculated, the DPF is recognised as inefficient.

A DPF is recognised as overloaded if the differentialpressure across the DPF exceeds the overload limitcalculated by the PCM.

A DPF is recognised as blocked if the differentialpressure exceeds the blocking limit calculated by thePCM.



Monitoring of the maximum regeneration attemptsin the lower load range: the DPF regeneration systemis designed to enable regeneration to be performed evenunder unfavourable conditions (low coolant temperature,engine speed and engine load).

In the worst case scenario, the system may startregeneration attempts but be unable to complete them.These attempts are counted by the PCM. If themaximum number of regeneration attempts is reached,this results in a fault entry the next time the ignition isswitched on.

Intake manifold flap actuator motors(Bosch system only)


E513731

2



During the regeneration phase, the intake manifoldflap closes off the air flow via the charge air coolerdepending on requirements. At the same time, uncooledcharge air is fed via the charge air cooler bypass flap.

The intake manifold flap actuator motor incorporatesa DC motor and a position sensor which detects thecurrent position of the intake manifold flap.

In the de-energised state (actuator motor not actuated),the intake manifold flap is fully open.

Effects of faults

In the event of a fault, limited regeneration is stillpossible depending upon how high the intake airtemperature is and the operating condition of the engine.

Note: For further information on the intake manifoldflap actuator motor, refer to "Lesson 5 - Actuators".

Charge air cooler bypass flap actuatormotor (Bosch system only)


E51674

During the regeneration phase, the charge air coolerbypass flap opens, enabling uncooled charge air to bedirected to the combustion chambers.

The uncooled air prevents cooling of the combustionchamber at low engine speeds/engine loads and thispromotes the regeneration of the DPF.

The charge air cooler bypass flap actuator motorincorporates a DC motor and a position sensor whichdetects the current position of the intake manifold flap.

In the de-energised state (actuator motor not actuated),the charge air cooler bypass flap is fully closed.



E51722

2

1

1

3

4

PCM1

Actuator motor2

Position sensor3

DC motor4

The DC motor is supplied with battery voltage by meansof the ignition relay in the battery junction box.

The actuation of the DC motor and therefore theadjustment of the charge air cooler bypass flap isperformed by the PCM connecting to ground (pulsewidth modulated).

The position sensor is supplied with a reference voltage.The voltage drop at the position sensor (variableresistance via sliding contact) signals the precise angularposition of the charge air cooler bypass flap to the PCM.

Effects of faults

In the event of a fault, limited regeneration is stillpossible depending upon how high the intake airtemperature is and the operating condition of the engine.

Diagnosis

Monitoring of the charge air cooler bypass flap (bymeans of the position sensor) includes the followingchecks:

• reference voltage of the position sensor,

• limit range check,


• control deviations,

• sticking charge air cooler bypass flap.



Intake manifold flap and charge air cooler bypass flap solenoid valves (Siemenssystem)


E54236

Intake manifold flap vacuum actuator1

Charge air cooler bypass flap vacuum actuator2


Charge air cooler bypass flap solenoid valve4

PCM5

The intake manifold flap has another function inaddition to restricting the intake air for exhaust gasrecirculation and closing the intake system when theengine is stopped.

During the regeneration phase, the intake manifold flapcloses off the air flow via the charge air coolerdepending on requirements. At the same time, uncooledcharge air is fed via the charge air cooler bypass flap.

Adjustment of the intake manifold flap is performed bythe intake manifold flap solenoid valve via vacuum.

During the regeneration phase, the charge air coolerbypass flap opens, enabling uncooled charge air to bedirected to the combustion chambers.

The uncooled air prevents cooling of the combustionchamber at low engine speeds/engine loads and thispromotes the regeneration of the DPF.

Adjustment of the charge air cooler bypass flap isperformed by the charge air cooler bypass flap solenoidvalve via vacuum.

In accordance with the requirements, the solenoid valvesare actuated at a specified duty cycle by the PCM.

Effects of faults

If a fault occurs at one (or both) of the two solenoidvalves, limited regeneration is still possible dependingupon how high the intake air temperature is and theoperating condition of the engine.

Diagnosis

Both solenoid valves are monitored for short and opencircuit.



Overview of the DPF

Illustration shows the DPF in the exhaust tract of the 2.2L Duratorq-TDCi (DW) diesel engine

7

1 42 3

56

7

1 42 3

56

E97474


Flexible pipe2


DPF4

Rear pipe to the DPF differential pressure sensor5

Front pipe to the DPF differential pressure sensor6


7

The coated DPF is shaped like a honeycomb and is madefrom silicon carbide, similar to the DPF in the systemwith fuel additive (see relevant section in this StudentInformation).

A passive regeneration of the DPF is possible attemperatures above 300 °C with the aid of the coating(platinum ceroxide).

In this temperature range, the trapped diesel particulatesare converted catalytically.

The exhaust gas temperature required for passiveregeneration is often not attained. In this case, thetrapped diesel particulates must be burned off from timeto time with the aid of an active regeneration process.

Passive regeneration

The exhaust gases flow through the walls of the siliconelement. In doing so, the diesel particulates remainadhered to the ceramic wall that has been coated witha platinum ceroxide layer.

Oxidation of carbon monoxide (CO) andhydrocarbon (HC):

• As with the oxidation catalytic converter, CO andHC are oxidised. With high levels of CO and HCexhaust emissions, the energy release is considerable.The resultant jump in temperature acts directly atthe point at which high temperatures are required foroxidising the diesel particulates.

Oxidation of nitrogen monoxide (NO) into nitrogendioxide (NO2):

• NO is oxidised into NO2 at the catalytic coating.

• NO2 is a more active oxidation agent than O2 andtherefore oxidises the diesel particulates even at lowexhaust gas temperatures (from 300 to 450 °Capprox.). The effect is known as the CRT(Continuously Regenerating Trap) effect or aspassive regeneration.


Coated diesel particulate filter (DPF)Lesson 6 – Engine Emission Control

Oxidation of carbon monoxide (CO) into carbondioxide (CO2):

• Another operative mechanism is the oxidation of theCO, which is produced at low regenerationtemperatures during the oxidation of dieselparticulates, into CO2. The combustion of dieselparticulates is improved by the localised generationof heat.

At temperatures from 300 °C to 450 °C (attained largelyoutside of cities), a passive regeneration of the DPFtherefore takes place continuously. It is not necessaryfor the engine management to intervene.

Active regeneration

For situations where the vehicle is frequently driven forshort distances, active regeneration must be initiated atcertain intervals.

The PCM registers the engine's operating data andinitiates active regeneration after evaluating the datafrom the DPF differential pressure sensor.

An attempt is then made by the engine managementsystem to attain the necessary temperature ofapproximately 600 °C for combusting the trapped dieselparticulates. The following measures are taken toachieve this:

• a post-injection close to the main injection,

• increasing the injected fuel quantity,

• retarded main injection,

• restricting the intake air via an intake manifold flap,

• a second post-injection at a distance from the maininjection (if necessary).

Note: The measures listed above are not always allactive. The map decides the measures that have to betaken to increase the temperature as a function of theoperating conditions.

During active regeneration, the EGR system isdeactivated.

The active regeneration process can take up to 20minutes.


The coated DPF is installed in the vehicle for life. Ittherefore has no maintenance intervals (at the time ofgoing to print).

However, if it is necessary to install a new DPF, aparameter reset must be performed via the IDS.

With some versions, the parameters of the DPFdifferential pressure sensor must also be reset. In thisregard, always refer to the instructions in the currentService Literature.

Notes on the oil change interval

High exhaust gas temperatures of approx. 600 °C mustbe generated for active regeneration of the coated DPF.

With frequent journeys in the lower partial loadrange, the maximum number of available measuresmust usually be taken to attain the exhaust gastemperature necessary for an active regeneration.

The intervals between the individual regenerationprocesses are then also shorter, so that the maximumnumber of available measures have to be taken moreoften.

When using the maximum number of availablemeasures, retarded post-injection is frequently used.

Retarded post-injection results in a greatly increaseddilution of the engine oil. In extreme cases, this meansthat the engine lubrication is no longer adequatelyguaranteed.

In order to detect excessively diluted engine oil, an oilquality calculation strategy has been implemented inthe PCM software.

This strategy calculates the oil quality, taking intoconsideration the engine operating conditions and themeasures for increasing the exhaust gas temperatureduring the regeneration processes.

If the strategy determines more than 7 % fuel in theengine oil, a corresponding text message is activated inthe instrument cluster. This text message signals to thedriver as well as to the Ford Service personnel that anoil change must be carried out ahead of schedule.

After each oil change, the parameters for the oil qualitycalculation must be reset (see also the instructions inthe current Service Literature).


Lesson 6 – Engine Emission ControlCoated diesel particulate filter (DPF)

DPF regeneration indicator (2006.5Transit only)

E98563

It is not always the case that vehicles are operated inthe temperature ranges required for regeneration of theDPF.

The indicator indicates to the driver when there is a riskof the DPF becoming overloaded.

Illumination of the indicator signals to the driver thatthe vehicle needs to be operated at a higher engine speedto initiate and complete an active regeneration process.

To this end, the vehicle should be driven at a higherengine speed for at least 30 minutes. Long periods ofidling should be avoided.

The indicator goes out again following successfulregeneration. The vehicle can now be used as normal.

If the required active regeneration process cannot besuccessfully completed, in addition to the DPFregeneration indicator, the MIL is also switched on.If this happens, the vehicle must be brought to thenearest Authorised Ford Dealer. The technician caninitiate active regeneration using the IDS.

If in addition to the DPF regeneration indicator and theMIL the transmission control indicator is alsoswitched on, a new DPF must be installed.

Note: If the vehicle is mainly operated with sufficientexhaust gas temperatures, it is very possible that theDPF regeneration indicator will never come on. Withsufficient exhaust gas temperatures, the vehicle is alwaysable to independently initiate and complete the necessaryregeneration processes.

Intake manifold flap


Illustration shows the system with vacuum control

E98519

The intake manifold flap is located in a housing that ismounted directly on the intake manifold.


A high temperature (approx. 600 °C) is needed to burnoff the diesel particulates trapped in the DPF. Thistemperature, however, is not attained in all of theengine's operating conditions.

Under certain operating conditions, the intake manifoldflap is partially closed in the lower partial load range.

The resulting lack of fresh air intake results in thecombustion chambers no longer being cooled as sharply.This helps to increase the exhaust gas temperature.



Components of the engine emission control system

1

3

4

5

6

7 8

9

10

2

11

1

3

4

5

6

7 8

9

10

2

11

E98520


1



MAP sensor4

Intake manifold flap position sensor (only withvacuum-controlled systems)

5

PCM6

CAN7

DLC8

Intake manifold flap solenoid valve (only withvacuum-controlled systems)

9

Fuel injector10

Intake manifold flap unit (with systems withelectrical actuator unit)

11


Before installing a new PCM or before loading newsoftware as well as after installing a new DPFdifferential pressure sensor, always read the instructionsin the current Service Literature.



Exhaust gas temperature sensor(s)


E48497

One or two sensors are installed, depending on thesystem.

System with one sensor:

• The sensor is located immediately upstream of theDPF.

System with two sensors:

• One sensor is located upstream of the oxidationcatalytic converter and

• one sensor is located immediately upstream of theDPF.


The exhaust gas temperature of at least 550 °C to 600°C required for burning off the diesel particulates isdetected by the sensor(s) and transmitted to the PCM.

Depending on the exhaust gas temperature calculated,the PCM decides whether or not the regeneration processcan be initiated.

Effects of faults

In the event of a fault, the PCM calculates a substitutevalue.

Specific regeneration of the DPF, however, is no longerpossible.

Diagnosis



• logical rise/fall rate of the signal, wherebyintermittent faults are detected (e.g. loose connectorcontacts),

• for plausibility.

DPF differential pressure sensor


E59691

The differential pressure sensor is located in the enginecompartment, near the bulkhead.


The sensor measures the current exhaust gas pressureupstream and downstream of the DPF and determinesthe differential pressure based on the readings.

For this purpose there is a pipe connection upstreamand downstream of the DPF.

The readings are converted by the sensor into a voltagesignal and transmitted to the PCM.

The soot particles and ash collected in the DPF resultin a change in pressure in the exhaust gas streamupstream and downstream of the DPF. The alteredpressure value owing to the ash/soot load is used by thePCM as an input variable for determining soot and ashload.



Furthermore, the sensor detects a defective DPF.

Effects of faults

If the sensor is defective, the PCM calculates the timingof the next regeneration.

Overloaded or blocked DPF:

• The PCM continuously calculates the load status ofthe DPF from the engine's operating conditions andfrom the input variable of the sensor.

• With an increasing soot load, the engine torque isalso continuously reduced.

• If the DPF is blocked, the MIL is set.

Diagnosis



• the measured sensor values for plausibility(comparison with the map data).

Via the sensor, the monitoring system detects:

• an overloaded/blocked DPF. (The pressure dropacross the filter is too great and the differentialpressure exceeds a calibrated maximum value.)

• a defective/missing DPF. (The pressure drop acrossthe filter is too low and the differential pressure fallsbelow a calibrated minimum value.)


With some systems, it is necessary to carry out aparameter reset using the IDS after installing a newsensor. In this regard, always refer to the instructionsin the current Service Literature.

Intake manifold flap position sensor(vacuum-controlled systems)


E97945

The sensor is installed at the intake manifold flaphousing, near the intake manifold flap.


In vehicles with coated DPF, the exact position of theintake manifold flap has an effect on the activeregeneration process (see the section "Intake manifoldflap" in this lesson).

The sensor works inductively (contactless) and istherefore insensitive to slight contamination.

The sensor is supplied with a reference voltage (5 V ±5 %). The analogue output signal to the PCM is between5 and 95% of the reference voltage.

Effects of faults

Specific regeneration is only possible to a limited extent.In extreme cases, this leads to overloading of the DPFand thus to reduced engine power output.

Diagnosis


• the sensor for short to ground/battery (by means ofa limit range check) and open loop,

• the logical rise/fall rate of the signal, wherebyintermittent faults are detected.


Following installation of a new sensor, it must beinitialised using the PCM (refer to the instructions inthe current Service Literature).



Intake manifold flap unit


Intake manifold flap unit with integrated actuator motorand position sensor

E98522

The unit is mounted directly at the intake manifold.


The intake manifold flap is partially closed as requiredduring the active regeneration process. This helps toincrease the exhaust gas temperature.

The intake manifold flap unit consists of the followingcomponents:

• intake manifold flap,

• actuator motor,

• position sensor.

The intake manifold flap is operated by a DC motor.Actuation is performed via PWM by the PCM.

The current position of the intake manifold flap isdetected by a position sensor (potentiometer). The outputsignal is an analogue voltage signal.

Effects of faults

Specific regeneration is only possible to a limited extent.In extreme cases, this leads to overloading of the DPFand thus to reduced engine power output.

If the intake manifold flap becomes jammed closed, theengine cannot be started.

Diagnosis

Intake manifold flap unit monitoring is divided into thefollowing steps:

• Monitoring of the DC motor via the PCM outputstage

• Monitoring of the position sensor:

– Limit monitoring: the PCM constantly checks ifthe incoming signal is within the limits.

– Monitoring for short circuit and open circuit.

– Reference voltage monitoring.

• Monitoring of the intake manifold flap:

– The position sensor detects a jammed or stickingintake manifold flap.


With some systems, it is necessary after installing a newintake manifold flap unit to carry out an initialisationusing the IDS. In this regard, always refer to theinstructions in the current Service Literature.



General

1

2

3

4

2

5

6

7

8

9

1

2

3

4

2

5

6

7

8

9

E98530

Fuel vaporiser system fuel pump1

Fuel line2

Non-return valve3

Fuel vaporiser4

Centring5

Fuel outlet bore6

Electrical connection for glow plug7

Main oxidation catalytic converter8

DPF with integrated oxidation catalytic converter9


Lesson 6 – Engine Emission ControlFuel vaporiser system

NOTE: At the time of going to print, the fuel vaporisersystem is only planned for the 2.4L Duratorq-TDCi inthe 2006.5 Transit.

For space reasons, the coated DPF of the 2.4LDuratorq-TDCi (Puma) diesel engine is located farbehind the main oxidation catalytic converter. Theexhaust gas temperature (approx. 600 °C) generated byengine-based measures for active regeneration of theDPF would cool too rapidly before the DPF is reached.Active regeneration of the DPF would therefore not bepossible.

To attain the necessary exhaust gas temperature foractive regeneration, a fuel vaporiser system is installedhere.

With the help of the fuel vaporiser system, vaporisedfuel is injected to the exhaust tract. The vaporised fuelreacts in the second oxidation catalytic converter, whichis located immediately upstream of the DPF. Thissecond oxidation catalytic converter and the DPF arecontained in a single housing.

Through the reaction of the vaporised fuel in the secondoxidation catalytic converter, the exhaust gastemperature of around 600 °C required for burning offthe trapped diesel particulates is attained.

The fuel vaporiser system is actuated by the PCM underthe following conditions:

• The trapped diesel particulates must be burned offwith the aid of an active regeneration process.

• The exhaust gas temperature upstream of the DPFmust be at least 205 °C.

The fuel vaporiser system is activated during the entireactive regeneration process (approx. 10 - 15 minutes).


After working on the fuel vaporiser system (e.g. afterrenewing the fuel vaporiser system fuel pump or one ofthe fuel lines), the system must be bled.

After cleaning the fuel system (e.g. due to incorrectrefuelling of the vehicle with petrol), the fuel vaporisersystem must also be cleaned and then bled.

In this regard, always refer to the instructions in thecurrent Service Literature.

Fuel vaporiser system fuel pump


E98544

The fuel vaporiser system fuel pump is a reciprocatingpiston pump. The pump stroke is generatedelectromagnetically.

All cavities are filled with fuel in currentless state. Whenthe solenoid coil is energised, the solenoid armaturepushes the pump plunger against a spring. The pumpplunger opens a non-return valve in the pump and expelsthe fuel. The pump plunger simultaneously closes thebores to the pump chamber. At the same time, thearmature chamber is filled with new fuel. If the poweris switched off, the spring pushes the solenoid armatureand the pump plunger back. This creates a vacuum andthe fuel enters via the bore.

The pump delivers fuel to the fuel vaporiser for theduration of the regeneration process.

The fuel pump is actuated by the PCM during activeregeneration with a frequency of 6 Hz.


After installing a new fuel vaporiser system fuel pump,the fuel vaporiser system must be bled. In this regard,always refer to the instructions in the current ServiceLiterature.

Effects of faults

If the pump is defective, active regeneration can nolonger be carried out. The result is a blocked DPF.


Fuel vaporiser systemLesson 6 – Engine Emission Control

Fuel vaporiser


E97163

1 2

4

3

5

Fuel vaporiser1

Glow plug2

Fuel vaporiser chamber3

Fuel outlet bore4

Non-return valve5

At the start of the regeneration process, the glow plugin the fuel vaporiser is actuated by the PCM.

A few seconds later, the fuel vaporiser system fuel pumpdelivers fuel to the fuel vaporiser chamber.

The delivered fuel flows past the heated glow plug,vaporising in the process. The vaporised fuel then flowsinto the exhaust tract via the outlet bore.

The non-return valve ensures the necessary pressureand prevents the fuel line draining. The fuel is admittedinto the fuel vaporiser chamber at a pressure of less than2 bar.


Lesson 6 – Engine Emission ControlFuel vaporiser system


1. What is the fuel additive used for?

a. To enhance the performance of the engine.

b. To lower the NOX emissions during the regeneration process.

c. To support the combustion of HC emissions inside the engine.

d. To lower the combustion temperature for the deposited diesel particulates.

2. What is the advantage of the coated DPF?

a. No interventions by the engine management system are required.

b. Active regeneration can take place at 300 °C.

c. The fuel additive tank is designed with a large enough volume so that no fuel additive needs to be toppedup for the service life of the vehicle.

d. No fuel additive is required.

3. What must be performed on vehicles with coated DPF after each oil change?

a. A reset of the parameters for the soot load of the DPF.

b. A reset of the parameters for the oil quality calculation.

c. A reset of the differential pressure sensor parameters.

d. A visual inspection of the DPF for signs of overheating.

4. The fuel vaporiser system

a. pumps fuel from the EVAP (Evaporative Emission) canister directly into the exhaust tract.

b. injects vaporised fuel into the exhaust tract.

c. injects vaporised fuel directly into the engine cylinder during the exhaust stroke.

d. injects vaporised fuel directly into the intake tract.


Test questionsLesson 6 – Engine Emission Control


1. b

2. c

3. d

4. c


1. b

2. a

3. b

4. c

Lesson 3 – Powertrain Control Module (PCM)

1. c

2. a

3. d

4. c


1. c

2. a

3. b

4. c


1. d

2. c

3. a

4. c

Lesson 6 – Engine Emission Control

1. d

2. d

3. b

4. b

Service Training162

Answers to the test questions

Anti-lock Brake SystemABS

Accelerator Pedal PositionAPP

Barometric PressureBARO

Bottom Dead CenterBDC

Brake Pedal PositionBPP

Controller Area NetworkCAN

Cylinder Head TemperatureCHT

Crankshaft PositionCKP

Camshaft PositionCMP

Carbon MonoxideCO

Carbon DioxideCO2

Clutch Pedal PositionCPP

Direct CurrentDC

Data Link ConnectorDLC

Diesel Particulate FilterDPF

Diagnostic Trouble CodeDTC

Engine Coolant TemperatureECT

Exhaust Gas RecirculationEGR

European On-board DiagnosticEOBD

European On-Board Diagnostics

Engine Oil PressureEOP

Erasable Programmable Read OnlyMemory

EPROM

Evaporative EmissionEVAP

Generic Electronic ModuleGEM

HydrocarbonHC

Heated Oxygen SensorHO2S

Intake Air TemperatureIAT

Integrated Diagnostic SystemIDS

Knock SensorKS

Mass Air FlowMAF

Manifold Absolute PressureMAP

Manifold Absolute Pressure AndTemperature

MAPT

Malfunction Indicator LampMIL

Oxides Of NitrogenNOX

Negative Temperature CoefficientNTC

OxygenO2

Passive Anti-theft SystemPATS

Powertrain Control ModulePCM

Positive Temperature CoefficientPTC

Pulse Width ModulationPWM

TurbochargerTC

Top Dead CenterTDC

Temperature And Manifold AbsolutePressure

T-MAP

Vehicle Speed SensorVSS

Worldwide Diagnostic SystemWDS

163Service Training

List of Abbreviations

Technical Service Training

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Transcript of Technical Service Training