I'm going through a bunch of shady wiring on a new (to me) '86 Z28 that I just bought. The car has idled consistently at about 1250rpm in the week that I've owned it. Tonight I noticed that the MAF is not plugged in; it was dangling beside the sensor connector.

I was about to take the throttle body off to clean and inspect it anyway, so I didn't think anything of it. I cleaned off all of the deposits from the throttle body and thoroughly cleaned the MAF with a proper MAF cleaning spray. After I reassembled it, ensured that the MAF plug was secured properly and fired the car up, it idles between 2000-2500rpm. When I unplugged the MAF the idle again dropped to 1200ish as it had been running before.

I am getting both codes 32 and 33. Is it safe to assume that the MAF itself is shot, or does this point toward a different problem all together?

 

Tomorrow after work, I guess I'm going to start with checking out the IAC sensor.

 

Alright, I finally got my IAC out, I discovered that it was completely seized with carbon and rust. No amount of wiggling or turning could budge it. I bought a new one and installed it, following the instructions on resetting the IAC and minimum air adjustment screw here on TGO.

I know of a small vacuum line leaking, and perhaps there are others, but I could not set the idle to 400-450 RPM's per the guide. I got it as low as I could and after hooking the IAC back up and starting the car with all sensors and harness plugs inserted, the car is idling at about 850 RPM's in gear. This is a step in the right direction, so I'll continue to try to figure out why I can't idle any slower.

 

IMHO 450 rpm idle is too low. Mine idles at 1200 in park and that seems fine.

 

Yeah, I don't think I'm going to get this car to run as low as its "supposed to". I fixed my one and only vacuum leak. The TPS was about the only brand new part on the engine when I bought the car so I never even thought to check it. Well, last night I did and it was only at .24 volts. I've got it up to .54, going to try to adjust the idle again today.

 

450=too low & 1200=too high (almost double)

It should idle closer to 650/700.