I have a 87 GTA with a 5.7 tpi. The car was running okay, a bit soft on the high end. All of a sudden when the engine was started, it would die right away. It was possible to keep the engine running if revved to 1,000 rpm, but if it dropped below that, the engine dies. We have replaced the fuel filter & have not been able to locate any vacuum leaks. The engine is showing trouble codes for the MAF & Knock sensors. Is it likely to be one of these, or is there something else that would cause these codes as well? I would hate to spend $200 on a MAF and still have the problem.

 

MAFs rarely go bad. Save your money, start elsewhere.

I'd check the throttle position sensor, its on the passenger side of the throttle body, has three wires hooked up to it. I think theres a tech article that says how to check it, or search for any post by Vader You will need to verify closed voltage (should be between .35 and .6V) and also make sure as you open it that the voltage steadily increases and doesnt jump around. IIRC its the center wire thats the signal wire, and then you just need to hook up a voltmeter to that and ground, and read it.

If thats ok, try replacing the MAF power relay. Check the timing too.

 

OK, I replaced the E.S.C., cleaned up the M.A.F., tested the T.P.S. came out at .54 volts closed throttle and 4.54 volts W.O.T. Voltage seemed stable as throttle was opened, also i ran the engine at 1000 RPM and read about 19gms/sec. At 2000 RPM it was 25gms/sec through the M.A.F. I have an error code 34 in the ECM. As far as the relay, where, what, and how.
I haven't a clue where to find this or test it. Also just for grins i removed the cat, but that did nothing.

any help is aprreciated

T.I.A.

AFAST87

 

87,

You can either replace the relays, or exchange the MAF burnoff relay with the MAF power relay. If the error code changes to a '36' or disappears, replace both of the relays to be safe.

If the problem persists, check the relay socket wiring connections, MAF electrical connector, and inspect the intake ductwork for cracks, splits, holes, etc. The plastic air resonator box in front ot the throttle body on your '87 is a potential source for hidden splits and cracks, so inspect it closely.

You should also look for any vacuum leaks. Make sure the CCV system is sealed and that you are NOT using a breather-type oil filler cap.

If the MAF error persists through all of that, you can "tap-test" the MAF sensor while the engine is idling. If tapping lightly on the MAF housing causes the engine to stumble or kill, you likely have a failed hot wire sensing element in ths MAF and need a replacement. If you determine a need to replace the MAF, I would suggest taking a close look at the Wells/Conrad SU-145 MAF replacement.

 

Thanks Vader!!
We just bought this car about two weeks ago. We got the car running and here is what we did…
The resonator box WAS leaking and we took care of that. The MAF relay needed to be replaced and we cleaned up the connections. We also decided to give the car a tune-up while we were at it. We found that whoever did the last tune-up only changed half of the spark plugs. After looking at the plugs, its a wonder it even ran at all. The cap & rotor were in just about as bad of shape. The timing was also about 6 degrees retarded. So… I think the idle problem was a combination of the MAF relay & the resonator box leaking. The car still seems a bit sluggish on top end but I think I still have a vacuum leak somewhere.
The MAF relay and resonator box was a wonderful tip! Thanks oh so much for the advice! :hail: