Mass Air Voltage Too High

[mhuckabee]

I was driving down the road the other day and my car just started dumping out black smoke and lost all power. After a day of troubleshooting, I found that my MAF voltage is 2.74 volts at idle. I have tested my MAF voltage in the past to troubleshoot a different issue, and at idle, voltage was .87. I also tested this on a buddys car, and at idle, his MAF voltage was under 1 volt.

Right away I thought the MAF was bad. I borrowed a buddys meter, it did the exact same thing. I put my meter on his car and it produced .8 volts at idle as it should.

I tested to make sure that I was getting 12 volts at the power going in to the meter as well.

Does anyone know what could cause this? Bad ground maybe somewhere?

I also tried 2 computers.

The car is an 89 GT

[u1arunit]

Injector stuck open or bad O2 sensor maybe?

[mhuckabee]

I should add that the car will run ok with the MAF unplugged, but that 2.7 volts at idle is telling the computer that there is significant air flowing into the engine and is dumping fuel to compinsate.

[StreetLethal]

Does the voltage change when you raise the rpm? or does it stay at that voltage?

[mhuckabee]

It does go up as you raise rpm

[mhuckabee]

Well I found the problem. The bypass valve was leaking, so the blower was pulling air through the meter and pushing it out of the discharge tube where the bypass valve connects.

[u1arunit]

Good deal. Glad you fixed it!

[billyNOTnice]

good find.