HOW TO - Test G70 AIR MASS METER (aka MAF Sensor)simon637404-10-10, 22:05

The air mass meter is a critical sensor and well known for causing performance issues. But don't rush into replacing it until you do these checks.

The signal from the air mass meter is required by the control unit to calculate the required injection quantity and to control the exhaust gas recirculation. The smaller the signal from air mass meter G70 the smaller the quantity of fuel injected.

TESTING (requires driver and VCDS operator)

1. open vagcom / select engine / meas blocks 08 / groups 010 and 0022. when at normal temp / accelerate from 1500 rpm atfull throttle in second gear/ at 3000 rpm press log or screen capture as above3. compare specification / block 4 accelerator position 100% / block 1 air mass drawn inabove 700mg/stroke/ renew if less than this4.if constant 550mg/H(predetermined value) indicates fault / switch off ignition / remove connector / switch on ignition / measure voltage supply between contacts as per diagram below

ADDITIONAL CHECKS AND MAINTAINANCE

* Check basics - hose connections from air cleaner to turbo. Any leaks will allow unmetered air into the system and reduce power.* A loose suction pipe leading from air cleaner to turbo inlet is the most likely culprit. Replace o-ring inside pipe and secure properly. See photo below* Remove sensor and spray liberally inside with Isopropyl Alcohol or similar to remove dirt, allow time to dry and refit.* Use electrical contact cleaner to remove deposits off connector plug, once dry apply silicone grease which acts as a good insulator. Remember the slightest improvement in voltage signals can have a dramatic effect on performance as the readings received by the ECU are more accurate.* Some people unplug the sensor to determine whether it is working or not. Unplugging it will trigger a DTC and the ECU will estimate injection quantities using predetermined values. In theory, if it runs worse then the sensor was working ok and if it runs the same or better than it may need replaceing. Personally I do not think this is a reliable method and should not be used.* Check wiring for short to one another / short to earth / short to positive / spec