Quote:
Originally Posted by CorSVXette
Just to get off the subject a little. Is there anyway to check if a MAF is in "good working order" when it is off the car?
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The short answer is no, Paul, not easily anyway.
You know what the maf does, I suspect. It runs a current through a wire to heat it up. The cooling effect of the air flowing past the hot wire cools it, requiring more current to heat the wire.
This variation in current is sent to the ECU as a range of voltage. If the ECU see voltages coming across that are outside the range it expects to use to define the fuel map, it sees this as a "fault".
From people working with the standard maf and superchargers or turbochargers, we already know by measuring the voltage on the car that at near to max airflow the voltage can be unstable. Unstable = inaccurate metering.
There is one thing you can do. Way, way back somebody took the top off the square part of a malfunctioning maf, got access to the circuits, and soldered loose connections inside that were causing his problem. He stuck it all back together, sealed properly, problem solved!
It would not surprise me at all if this fix would actually repair more than half the bad mafs out there; the bad connections are caused by a combination of age and temperature cycling from underbonnet heat.
To check the maf off the car you would need a factory set-up. You would need to feed the correct current through the pins, plus read the voltages coming off on the signal wire. You would also need to feed air through the chamber in a controlled arrangement to mimic the feed to the manifold, so that you could graph airfeed vs voltage output. It could be done but it's too much trouble.
Joe
