On a MAF sensor, isn't the voltage at Pin "C" supposed to increase as airflow increases?
I've tried 3 different (2 were re-manuf) MAFs, but the voltage does not change (just stays at 5 volts) and I keep getting a code 33.
I've checked and double checked the chassis and analog grounds, and I have batt voltage present at pin "E". No power is present at pin "D".
On my scanner, the MAF g/sec display shows the MAF to be working properly. Reads ~10 g/sec at a 1000 RPM idle.
I'm stumped...

 

hey welcome to my world, ive been dealing with this problem now for a month and a half. ive basically replaced everything but ecm and tps. were does the "C" wire go to? i havent checked that out yet, but im gonna.

 

Well I think I've found the problem. I was back-probing the maf connector for abt the millionth time and WALAAAAA!!! 2.5 volts.
Tweaked the MAF connector pins a little, sprayed a little contact cleaner on them, and so far so good. Re-installed the original MAF and it looks good too. I re-enabled the MAF high diag threshold to 55 g/sec, and no codes so far. Just made my 4th test drive of the night. May knock the threshold down to 45 on the next burn.

 

so the "c" terminal voltage was low? what should it be at? what other stuff can you clean the pin / connector with? thanks
chris

 

Actually the voltage was high at 5 volts.
The ECM sends the MAF 5 volts. The MAFs job is to pull that voltage down. The less air there is flowing thru the maf, the lower it pulls the voltage down. When the MAF is flowing its max, the voltage will be close to 5 volts. That's why is sets the "MAF high" code.

Probably should use some real contact cleaner on the connector pins. Some di-electric grease would be a good idea after you clean it.

 

First rule of electrical troubleshooting.. Check and triple check ALL connections before throwing parts at it.

Had the same thing on my car when new, the dealership was wanting to throw MAF sensors at it (8 week backorder on them back in '85). One spread female pin on the harness caused all the problem.

 

yeh there was a bent pin on myne, straitened it...nope not the problem. how do u measure the volts at "C". do u do it with the car on or off? thanks
chris

 

You'll need something like a really small drill bit, some safety wire, telephone wire or something similiar to push into the back side of the connector. The idea to make contact with the pins with the connector still connected to the MAF. You need to sample the voltage between pins "C" and "B". This is done with the key in the run position but eng not running. You should see abt 2.5 volts.

Mine looked good too, but pin "C" wasn't making good contact.

 

check connection wirin and clip

 

oh my bad. never mind i thought it was a different problem sorry mister