ATASA 5 Emission Diagnosis & Service · 2019. 2. 18. · 2. Because it’s nearly _____ for an...

ATASA 5 th Study Guide Chapter 34 Pages 10091039 Emission Diagnosis & Service 43 Points

ATASA 5 th Emission Diagnosis & Service Please Read The Summary

1. The quality of the engine’s exhaust emissions depends on the __________ of the engine & the effectiveness of the emission control devices. (EGR, EVAP, EFE, CAT, AIR, PCV)

ATASA 5 th Emission Diagnosis & Service

Age Efficiency Make

2. Because it’s nearly __________ for an engine to always receive the correct amounts of air, fuel, and heat, even a good running engine will emit some amounts of pollutants.


Impossible Too Easy Automatic

3. The three, EPAregulated emission gases in gasoline & diesel engines are:


HC is present in the exhaust as a result of incomplete combustion, in ________________ blowby vapors and in evaporative emissions. Anything that causes a misfire or evaporation will result in HC pollution.

Misfire, Late Timing, or Restricted CAT Warms the Exhaust Mainfold Slightly!


Exhaust Crankcase Fuel Tank

CO forms when not enough _____________ is present during combustion. An overly rich A/F ratio can result in high CO. No CO and lots of HC = no burning took place.


Nitrogen Hydrogen Oxygen

NOx formed from _______ combustion temperatures, is the principle ingredient in photochemical smog. Stagnant air + NOx + sunlight = photochemical smog


High Medium Low

4. The IM240 is an ____________ & _______________ test & a ______ second emission test performed as the vehicle is driven on a chassis dynomometer simulate road conditions.


Inspection, Maintenance, 240

5. If a vehicle fails I/M 240, it is the job of the technician to determine under what __________ and engine speeds the vehicle failed.


NOTE: This is not the same as an OBDII drive cycle for noncontinuous monitors

Conditions Loads Speeds

6. The ____________ is the maximum allowable amount of each exhaust gas.


NOTE: These may differ from statetostate & from yeartoyear.

Cut point Break point Snap point

7. Gases both _________ and _________ the cut point are important for diagnostic reasons.


Initials Full Name Type Pollutants Lowered TAC Thermostatic Air Cleaner precombustion HC CO NOx EGR Exhaust Gas Recirculation precombustion HC CO NOx EVAP Evaporative System evaporative HC CO NOx EFE Early Fuel Evaporation precombustion HC CO NOx ~~~~~~ CAT Catalytic Converter postcombustion HC CO NOx AIR Air Injection System postcombustion HC CO NOx PCV Positive Crankcase Ventilation postcombustion HC CO NOx

East & West Above & Below Inside & Outside

8. Low amounts of 4 out of 5 of the major exhaust gases are desirable. ______ should be 12%15%.


O 2 CO 2 NO x

9. At _______________ (Lambda (£) of 1.0), HC & CO are at their lowest levels & CO 2 will be highest.


Stoichiometric Systematic Automatic

10. ____________ diagnosing the cause of excessive emissions, inspect the entire vehicle for obvious problems. Battery, filters, base engine, air induction hoses, fuel pressure regulator, EVAP & PCV, vacuum leaks, etc.


Before During After

11. Check both the_____________ and _____________________ OBDII monitors with a scan tool.


Note: DTCs cannot be set if a monitor is not run to test the system.

Large & Verysmall Continuous & Noncontinuous Continuity & Noncontinuity

12. EVAP systems will need to be smoke checked for small _________.


Squeaks Leaks Peaks

13. Canister _________ solenoids windings can be ohm tested. They can also be operated using the functional test Mode $08 in the scanner and “smoked” to see if they respond to commands.


Purge Merge Verge

14. A canister saturated with _________ or water causes back pressure in the fuel tank.


Exhaust Fuel Nitrogen

15. OEM diagnostic smoke machines use ___________ gas because it is inert and can’t support a fire.


Oxygen Nitrogen Hydrogen

16. Fuel ______ testers create a pressure so leaks can be detected.


Cap Tank Line

NOTE: Both small leaks (under .040”) and gross leaks (over .080”) anywhere in the EVAP system can be found by the onboard leak detection strategy, which is part of the EVAP selfdiagnostic system.


NOTE: Low amounts of 4 out of 5 of the major exhaust gases are desirable. CO2 should be 12%15%.


NOTE: Low CO 2 readings result from a Rich A/F mixture.


NOTE: Higher than normal NOx can be caused by an inoperative EGR system or very lean A/F mixtures.

Electronic EGR


Phase 1 of the IM 240 test is the 1st 95 seconds under moderate load on a flat highway at 33 mph max.


Phase 2 of the IM 240 test is next 145 seconds under hard acceleration to 56 mph for 1.4 miles.


17. Some engines use a fixed ____________ tube in place of a PCV valve.


Orifice Expansion Drip

18. Stuck ________ PCV valves cause excessively lean A/F ratios.


Open Up Shut

Note: A PCV valve stuck open can also cause a rough idle and stalling.


19. A PCV valve should allow air flow only ______ way through it. When pinched off, you should hear a click. A restricted PCV valve results in blowby entering the air filter along with oil sludge.


One Two Ten

20. At idle, a _____________ sound should be heard in the PCV valve & a vacuum should be present.


Missing Hissing Kissing

21. PCV system operation can be upset by a leaking ____________, valve cover or oil filler cover.


Dipstick Transmission Differential

22. Until 2007, most diesel engines removed crankcase pressure & blowby with a ____________ tube.


Updraft Downdraft Sidedraft

23. Crankcase pressure can be measured with a water manometer connected to the ___________ tube.


Dipstick Transmission Differential

24. Too ______ or to ________ EGR flow can cause performance problems like rough idle, nostart, surging, stalling, detonation & excessive NOx if inoperative, and poor fuel economy.

EGR can be controlled by pulsewidth modulation of a vacuum switching valve


High, Low Much, Little Tall, Short

25. Diagnose ______ malfunction with scan tool Mode $08 functional tests & Mode $06 output state tests.


EGR PCV CAT

26. Vacuum operated EGR valves can be turned on with a vacuum__________.


Gauge Pump Scope

27. EGR vacuum regulator solenoids get their coils ohm tested for ___________ and _________. Note: a short coil in a control solenoid can damage a driver circuit in the PCM


Shorts & Opens Opens & Closed Above & Below

NOTE: A shorted EGR vacuum regulator solenoid (EVR) winding can either shut down (fail safe strategy) or if not shut down, will destroy the controlling quad drivers in the PCM.


NOTE: EGR on at all times will give a rough idle, poor performance, stalling or even a nostart.


EGR Valve

DPFE Hoses

EVR Hoses

Red EVR Hose = Manifold Vacuum Green EVR Hose = EGR Apply Vacuum

EVR = EGR Vacuum Regulator


IAC

DPFE

EVR

EVR Applies the EGR on the Command from the PCM

DPFE Verifies the EGR Valve actually turned on

DPFE = Differential Pressure Feedback EGR Transducer


NOTE: EGR off at all times will cause an IM240 NOx problem and detonation resulting in spark knock.


NOTE: Teeing a vacuum gauge into the EGR apply hose allows you to watch the vacuum switching.


NOTE: When EGR is energized with a vacuum pump at idle, the engine should stall. However, this only demonstrates that the valve opens & closes. It doesn’t indicate full proper system operation and proper metering of exhaust gases.


NOTE: The Knock Sensor (KS) is a major input to the PCM which directs EGR to turn on…and is the timing retard signal during detonation.


NOTE: A KS can be tested by lightly tapping with a small hammer on the engine block near the sensor while observing the spark timing retard on the scan tool.


NOTE: On some systems, A 12 volt test light intermittently touched to the KS wire leading to the PCM can also simulate a spark knock which should then “back down” the timing advance. View it with a scanner.


OLD SCHOOL NOTE: The PCM will switch the A/F mixture heater (EFE grid) on if the ECT is below 122 F°. (timer to limit operation)

Found on Carburetor

& TBI Systems

Maintains Fuel Vaporization Below the Throttle Plates in the Intake Manifold


28. The catalytic converter monitor looks at the converter’s ability to store ___. ATASA 5 th Emission Diagnosis & Service

29. A dead CAT will show the ________ waveform for the S1 (upstream) and S2 (downstream) HO 2 S.


Same

NOTE: A plugged (restricted) CAT causes a loss of or lack of engine vacuum, stalling & a loss of power.


30. An unrestricted CAT will show less than ____ psi of exhaust backpressure at 2000 rpm.


1.25 3.0 10.5

31. A “rattling” CAT indicates a ____________ catalyst substrate. (probably melted from misfire) Fix that problem too!!


Stuck Loose Missing

32. A CAT working to reduce emissions should be at least ____°F hotter outlet vs. inlet temperature.


5°50° 500°

NOTE: A functioning CAT will yield oxygen readings of 12 % in the exhaust stream. (CO 2 between 1215%)


33. A secondary air system (AIR) can cause an emission failure from either too ____ or too _______ flow and also from air flow at the wrong time past the oxygen sensors.


High, Low Much, Little Tall, Short

34. AIR divert solenoids can also be actuated with a ________ tool using Mode $08 functional tests.


Scope DMM Scan

35. All types of air injection systems have a ___________ ___________ valve in common. This valve prevents exhaust from entering the air pump itself or the control valves.


OneWay Check TwoWay Check Ten Way Check

AIR Diverter Valve AIR Check Valve


Vacuum Reservoir


OBD II Readiness Monitors


ATASA 5 Emission Diagnosis & Service · 2019. 2. 18. · 2. Because it’s nearly _____ for an...

Documents

Transcript of ATASA 5 Emission Diagnosis & Service · 2019. 2. 18. · 2. Because it’s nearly _____ for an...