I keep getting a code 34 (gm/sec low) on my 88 GTA. Replaced the MAF and both relays, but still get the code 34.

I am not sure if this is correct, but I read that at idle, you should read about 2.5V on the green wire coming from the maf, and that it should increase linearly with throttle.

I am reading right at .7v at idle and the voltage swings smoothly with varying throttle/rpm.

Any ideas???

 

Wiz,

Here's what I get with a true RMS digital MM:



Your results appear to be similar, and I don't get DTCs. Have you checked the TPS setting? The ECM relies on a TPS voltage to calculate the appropriate intake air flow. If your TPS is adjusted too high, the ECM will expect more flow than you are actually getting.

You also need to check for leaks in the intake tract, including the plumbing between the MAF and TB, TB gaskets, intake gaskets, vacuum hoses, and the PCV system and power brake booster. You need to verify that the PCV vent is connected at the TB instead of using a breather type oil filler cap.

 

Vader,

Thanx man.......TPS reads .55v at idle with no apparent loose hoses or vaccum leaks. Car seems to run fine otherwise.

Anymore ideas ???

 

I had a similar problem a few years ago, try to change the TPS a little and see if it helps....... I have mine set at .57 now.....

 

If anything, a lower TPS voltage should tend to "fool" the ECM into accepting the lower g/S reading from the MAF.

Make sure you aren't leaking air anywhere around the plastic air boxes, the bellow tubing between the MAF and throttle body, and anywhere other air could be entering the engine.

Not to bring up the obvious, but are you certain the MAF is oriented correctly? There is supposed to be only one direction it should be installed, indicated by flow marking on the outer shell. And, if it is a replacement, what type is it?