Can anyone tell me:

1. Is there a way to bench-test the MAF for an '86 coupe
2. Will a MAF from a '86 Camaro 305 work in the '86 coupe

any help will be greatly appreciated.

tia

 

The easiest way to test one is to use another from a good running car, they take less than 3 minutes to remove/install - find a friend with a TPI. The part numbers are the same for the TPI Camaro's & Corvette's, 305 or not. This information was easily found at Schucks.com, PepBoys.com, etc. by looking up the part number for each vehicle.

 

Actually, you can test it on the car if you either have a scan tool, voltmeter, or a lab scope. Scan tool is in grams per second, voltmeter and lab scope checks voltage. Answer to second question is a definite no. MAF for a 350 Camaro will not work either. Has to be for a corvette. [8D]

 

I've got a voltmeter. Where exactly should I be looking for voltage? I know there is a 5v signal voltage on terminal C and a 12v supply on A.

 

Let me go into a little more detail on this MAF issue.

My '86 coupe is throwing out two codes: 33 & 44. Here is what I found going thru the FSM for each:

code 33 - Went all the way to step 5 reading all voltages I should I should, ie, light stayed on when using test
light (step 3), read "0" volts on D (step 4), and read 5v at "C" (step 5). So that's telling me that
everything going into the MAF is good, its down to the connections or the MAF itself. THAT'S WHY I
WAS INTERESTED IN THE BENCH TEST.

code 44 - Went thru step 2 and my tests basically showed the ECM is bad. When I ground the diagnostic terminal
and measure the voltage at the O2 sensor, with the engine running, I get a constant .17v. I then
disconnected the O2 sensor, started the engine and the voltage stayed at .17v, then started dropping
to as low as .08v. I then tested ckt. 412 for a short to ground. I didn't find one. Consequently, the
only thing left is a bad ECM. AM I GOING DOWN THE WRONG PATH HERE?????

I thought I would attempt to fix code 33 first, then move onto 44. Thats why I asked the question about the "86 305 MAF. There is one available on EBay.

thanx for your help!!!

 

Code 44 is a lean code, which would probably coincide with the MAF problem. The MAF generates a 5v digital signal back to ECM and the duration between pulses tells the ECM, in so many words, the more frequency, the more airflow. Does your voltmeter have Hz? You can use the Hertz setting on the return signal to the ECM to see if the MAF is working. You should be looking for a change in hertz reading (more) when you snap the throttle. Carquest and lots of other A/P have rebuilt MAF's from A1 and sometimes you get lucky and get a good one. BTW, they all have good warranty's. Good Luck. [8D]

 

Unfortunately, my voltmeter doesn't have a Hz setting. Do you think it would be possible to read the voltage frequency using the voltage scale??? From what you are saying, it sounds like the return signal is acting like a AC voltage signal.

 

You can read a voltage signal, DC around 2 to 2.5 volts which is an average because your voltmeter isn't fast enough to switch from 5 volts to 0 and back. On a lab scope it is a what we call a square wave, or digital signal. It is either on or off. [8D]

 

I have a Genuine Bosch MAF Sensor from a very low mileage '88 I'll sell you. I paid $300 for it - it's yours for $200 and I'll pay the shipping.

 

ALL2kool---thanx for the offer. As soon as I'm sure about the MAF, I might take you up on your offer.

mech259---I replace the 1-wire O2 sensor with a 3-wire unit and that got rid of the code 33. Its still kicking out the code 44. I measured the voltage on the 5v signal lead and, at idle, it reads about 1.24v. as the rpms are increased, the voltage increases to 2.5-2.8v. The car seems to run smooth but, as soon as the SES light goes on, the idle roughens up a bit, but the voltages i read on the 5v signal lead didn't change. All these voltages are measured with the MAF connected and the car in PARK.

The other thing that is bothering me is that I went back thru the code 44 FSM and am still getting only .17v on the O2 sensor signal lead (with the diagnostic terminal grounded). At times, it drops to .02v with the engine running. I ckecked circuit 412 for shorts to ground and didn't find any. Thats leading me towards a bad ECM. Incidentally, the .17v is on the O2 signal lead with/without the SES light being on.

Any suggestions???

TIA