blackz28x07

My car is a 98 z28 with 89k miles on it and is an A4. At the beginning of winter when the cold weather came in(below freezing) my car had problems after starting for the first time in the morning. It would start up fine but then go from 1500 rpms to 1150 rpms(where it usually idles when cold) and then bog down and die. Took it to get a diagnostic since there were no codes being thrown and the technician said he only say the MAF sensor to have a slightly low voltage. So i unplug it before i start it in the mornings, when it was usually around 20 degrees and the car would be fine.

So i get a brand new MAF sensor and the car started fine when it was 18 degrees out. Now a bad cold front has came in and the temperature was 8 degrees. I go to start my car and it kind of lags for a second, but nothing not normal, and it goes all the way up to between 2500-3000 rpms and just completley dies. I then unplug the MAF and the car is fine. What is going on? Could it just be how cold the weather is(very unusal for Louisville, KY). The car was fine in 18 degree weather but not in 8

blackz28x07

well i don't know if this would cause the problem, but since my old maf was bad and i got a new one i searched that you had to reset the ecu because the ecu adapts to your old maf?

I thought that sounded dumb, but i didn't reset the ecu after i installed my new maf.

just tried the car again and it will still run when the maf is unplugged but won't when it is plugged in.

LS6427

iTrader: (2)

What happens if you start the engine and unplug the TPS? Does it rev and run normal too?
My PCM, about 5 years ago, BY ITSELF, went into a speed density tune. I don;t need my MAF or my Throttle Position Sensor, and it runs perfect.

blackz28x07

so you didn't get it tuned to speed density? it did it by itself? I've only driven my car once while the maf was unplugged and the shifts were rough, so i'll usually just keep it unplugged until the car is warmed up and then i'll plug it back in so the shifts are smoother. This whole thing has just been pissing me off, and it only does it when it's cold out.....like 20 degrees or colder.

LS6427

iTrader: (2)

Yes...as strange as it may sound, one day I unplugged my MAF to remove so I could clean it. I installed it back on the car after I cleaned it with MAF cleaner and I forgot to plug it back in. I drove around like that for like 4 days. Then I unplugged the throttle position sensor and went for a drive and everything was normal also. I was told by people in the PCM section here that the PCM defaulted or switched to a SD tune by itself. Whatever....it runs like its brand new so I didn't bother doing anything about it.

However..if I unplug the MAP sensor in the air lid while the engine is running, it runs like crap.

I searched and found a that a few other people have had that same thing happen.

blackz28x07

well it does run fine with the maf unplugged......where's the TPS located? I'll unplug that and see how it runs.

O yea thanks for the advice!! i love this sight and the users on here.

blackz28x07

well i kept the TPS and MAF unplugged and my car ran fine in park, but when i started driving it wouldn't shift unless i went above 2500 rpms. So i put the tps back in and it would shift where it usually does, but it was still a hard shift. So then i plugged the MAF back in(and since my car was warm it ran fine) and it shifted a lot smoother.

So if no one else has any ideas i might just unplug my MAF when i start it and plug it back it when it's warm. I'll stop doing that whenever it gets warmer(around 35 degrees)