86 trans am with the TPI 305 engine, this car was running ok with no codes and just has been sitting over the winter. I started it once a month, now I get a code 34, which I believe was a MAF error. Tried replacing with another known good MAF sensor, no help..funny thing is the code explanation I found said something about a voltage reading over 2500 rpm and this code comes up with the engine just idling. Any ideas on what I should check next?

 

I had this happen on my 88. Code 34 is generally a stuff problem to solve. It took me over a year of troubleshotting to eventually figure out what was setting it off. Since you swapped the MAF out and it did not fix it. You can probably be pretty sure it is not the MAF itself. Generally, when the MAF it self goes bad it set's a code 33 instead of a 34.

In my case it turned out the fuel injectors were leaking and causing the code 34. My research over the years on this problem has turned up that leaking injectors to be a very common cause of the code 34 in tpi cars.

From what I can tell here's what happens. The injectors coils will test fine with an ohm meter but the injectors slowly leak fuel into the cylinders. Then the cylinders have to much fuel in them and the computer thinks there is not enough air and to match the fuel and bam a false code 34. The computer has no way to tell you something is wrong other then the code 34. Because the injectors are only controled by the ecm but provide no failure signals to it if there is a problem with them.

My .02 cents is swap in a new set of injectors. Also be sure to check your tps voltage and make sure it is at .54. I misadjusted tps is also another common cause of a code 34.

Tell you what check your tps voltage first before swapping injectors and let me know the results. We can start there with the diagnois process. I will try and walk you some tests.

 

Before you start ripping out injectors, try replacing your MAF power and burn off relay. My 88 was thowing a 34, and I fixed it by replacing the relays.

I also had leaky injectors a few years ago, never threw a code 34 though.

 

DIng ding dign . I had this problem too . Was the stupid relay . It causes alot of code 34 . Which I thought 34 was actually for the relay not the sensor.

 

Thanks for the responses guys, I will give the relay a shot. Which one is it on the bank of 3 on the firewall?

 

Their is two MAF relays. One is a burnoff relay and one is a power relay. You can try changing both and see if that solves your problem. If not you will need to begin troubleshooting. The below image is a page I scanned directly out of my GM service manual. I hope this helps.

 

I am getting a 34 in my firebird, it runs fine, but when i shift or it isnt in gear it dies, and has been hard to start, did you have any of these problems?
BTW, the flowmaster exhaust you gave me sounds better than the flowmaster that was on my car when i came to pick up the parts,
Mike

 

Hey Mike, no issues with the car other than the code being thrown. I ended up taking the car apart before I got to swap out the relay, gonna try that as soon as the engine is back up and running again. Have a good one!

 

how did you end up making out dave?

I am having sporadic code 34 now. I think its probably one of the relays, just need to swap em.