I'm getting a code 34 (MAF sensor) for my 86 Iroc. I put in a new MAF sensor, which didn't fix anything. My mechanic thinks I've got a vacuum leak somewhere but he can't find it. The engine sputters at low rpm and generally runs rough, as if it did have a vacuum leak. But, it's not idling too high, so if there is a leak it's small.

has anyone ever dealt with a code 34 on a 305 tpi where replacing the MAF didn't fix the problem? It's been six weeks and I'm at my wits end. replaced my throttle body to plenum and plenum to upper runner gaskets last night. nothing. I've cleared the code.

if anyone can offer advice I'd really appreciate it. thanks.

 

You have MAF power and burnoff relays, 86 I think is piggybacked on the ECM package, my 89 has them on the firewall. Try tapping on the control relays and see if it changes. A decent mechanic should have a scan tool to look at MAF gram/sec flow although I am not sure about 86's. It's a shame you spent money on the MAF assy, most times it is the supply relays that are the problem.

 

Thanks for the suggestion. Where on your firewall are the relays located?

I took a chance on the new MAF, and lost.

 

Among the LAST places I'd look is the MAF sensor itself. If the burn off cycle is working and the hot wire is clean, the sensor should either work, or not. There's very little middle ground, except for poor electrical connections.

Check the intake air ducts for leakage, including the accordian bellows. Also look closely at the PCV valve and hose, power brake booster, EVAP purge hose and valve, and crankcase vent supply tube. Make sure you don't have a pretty chromed breather type oil filler cap, since that will create a '34' almost immediately. The TPS voltage also needs to be set correctly.

 

BTW - This is the layout of relays on my '86 TPI:

 

Guys, it was the MAF power relay. When tapping did nothing, I took it out and cleaned the terminals off. Sure enough, everything is running normal now, no Code. I'm still crossing my fingers, but I think she's fixed. I can't believe it took me six weeks and my mechanic missed it. Thirdgen.org rocks!

thanks for your diagrams and other suggestions Vader. Man, you guys don't know how relieved I am to get this solved.

 

No need for thanks. After all, YOU did all the work. Still, it's always nice to know the outcome.

Just give back a little when you can to help out the next member. THAT is what makes this a pretty good place to visit.

 

Hey guys.. Just wanted to say thanks for this topic! Just picked me up an 87 Z28 with 305 TPI.. The previous owner assumed the MAF was bad.. I started doin some research. 3.8TransAM told me to find some posts by Vader. All in all it led me here and this was the exact problem. Still had some CRC QD Electronic cleaner left over from cleaning the MAF.. Gave it a go and no more code! Saved me one big headache and a hole in my pocket book.

Thanks!

 

similair situation, but i have maf code 34 and 36. was looking at maf sensor first but from threads read i will look to power and burnoff relay's first. my question to vader and everone else is, is that 86 pic the same setup for an 88 and also i was told the fan relay and maf power and burnoff relay's are interchangable. what do tou think?

 

I think my MAF relay was actually in the place of Vader's fuel pump relay. but my MAF relay was clearly marked "MAF Power" or something like that (car's in the shop now for new windshield, or I'd check), so it was easy for me to find. your setup may be different...but I'm definitely not the expert on this matter.