Thread: Air Flow Meter on a 3.9

Originally Posted by Camo

Hi there

Just wondering if anyone knows a way of testing an airflow meter. My 3.9 in my rangie has suddenly lost power and is using about 5l/100 k more fuel. Engine dosn't smoke or run rough..just feels tired but I don't believe its the actual motor.

Cheers

Camo

Looks like it might be a job for Rovacom and a Emissions Gas Tester.......

The resistance of the unit can be tested with a multimeter but I do not know what the values are meant to be. Any competant LR mechanic will be able to tell you is it is stuffed or just in need of adjustment.

Justs a thought have you checked the vacuum advance on the dizzy? These do periodically fail which could be contributing.

IMHO its quite easy to check the MAF.
If I recall correctly there are 4 wires.
1 is 5volt feed
2 is earth
3 is reference voltage ( the end nearest the engine)
4 is signal to ECU
With a volt meter and the engine idling check each wire
If it is working properly the power wire will be 5 volts
The earth will be nothing
The reference will be a constant 0.5 -1.5 volts
The signal will vary from a low value upwards with engine revs.
If you have 2 with nothing you have a problem.
As long as the voltage on one wire varies with engine revs, you can be pretty sure it is OK, as they usually fail open circuit.
Also check that the terminals on the connector are clean
Regards Philip A