got a code:
33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor)
and a
36. Burn off at mass air flow sensor OR
Problem in transmission shift OR
Fault in direct ignition system OR
Missing pulses in electronic spark timing signal
Car has (since i got it running about 2 weeks ago) always had a miss from idle to about 2500. But only now has these 2 codes shown up. Car will also randomly, around once a day, just bog down to about 500 rpm and start backfiring really bad if i try to give it gas, though it will idle just fine. The funny thing is all i have to do to make it run normal again as far as boging down is just disconnect that battery and hook it back up again. I know this is really confusing, so any help would be appreciated. By the way its an 86 LB9.

 

Holmes,

Your LB9 is a TPI engine, therefore, it has a MAF sensor, not a MAP. The code '33' is for unexpectedly high voltage (high indicated intake flow) from the MAF sensor. The '36' is for a MAF sensor burn-off cycle fault.

Chances are the MAf burn off relay or circuit has a problem. This may be affecting the '33' as well. Check/replace the relay and clear the error codes, then see what you get.

 

Vader, where is the MAF relay located? This is probably a stupid question but im 17 and this is my first f-body, still getting used to working on cars. Also i just copied and pasted what those codes meant from the tech articles on this site, so i didnt take the time to revise them. While we're at it, what do you think are any probable causes for it missing at idle to 2500 rpm? Thanks.

 

Holmes,

Your car has two relays for the MAF - one for power, and one to control the burn off function.



A quick check would be to exchange the MAF power and burn off relays, then clear the codes. If you generate another error code, check them again and report back.