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I need some help. I am restoring a z51 4+3 yellow coupe. My MAF is making me pull what is left of my hair out.
The stock MAF works but pulls a code 33. If I run the AC the car will have a tough time idling, but the car will run.
i purchased a replacement amazon $80 MAF and the car will run only when warmed up. I have to pedal it to get it to run and it backfires. It will not run at all with the AC on.
I returned the cheap MAF and purchased a Delphi MAF.
Now I get no code but the car will not run. I have to pedal it to get it to move and it backfires.
I replaced the burn off relay and the MAF relay, but still same result.
Adam I think we need more info.
Has it ever idled / run correctly ? When did it start to fail, suddenly or slowly ?? How is timing ?? How old / clean is fuel ??? Has it sat a long time ?? will it idle better if you unplug the MAF ?? Why do you suspect the idle problem and the MAF are related ?? What is the fuel pressure ?? Have you checked the fuel pressure regulator vacuum port for raw fuel / gasoline smell ?? Is ECM coolant temp sensor good ?? Have you double checked plug wires ??
Any other codes ??
Last edited by Vets-Vet; Jul 29, 2025 at 03:21 PM.
I suspect it is the MAF because I keep getting code 33 or 36 codes.
it did run fine with code 33.
Car was sitting a long time.
I tuned the car up.
New fuel pump, cleaned out the fuel tank and new fuel filter.
set the timing to 6deg advanced, with the car warmed up.
fuel pressure is good at 55psi
No other codes.
I would do the base idle set procedure with the original maf that it runs with and then try swapping mafs. A janky base idle setting or sticky or bad IAC could be confusing your results with different maf's.
Make sure you check the grounds also. The system ground is always there I am not sure about the analog ground. The MAF power relay is very important as well.
Do you have the ability to see ECM / OBD1 data.
Sorry about the code 33 question I confused it with the burn off code 36.
.
Last edited by Vets-Vet; Jul 30, 2025 at 07:16 AM.
None of the few relays I've looked at were anywhere near as well made as the original GM ones. I'm pretty sure one could replace them both with the correct Bosch ones with a little work.
1986 MAF problems
