TPI problem is it the IAC? - Third Generation F-Body Message Boards

UK-1991-Z28 · 09-22-2009, 01:09 PM

Hi guys im over in the uk. 1991 350 tpi engine code 8. I have replaced all the vacume hoses, plugs, leads, dizzy, rota arm and fuel filter. The rev counter dose not work so the revs are a guess. The car was hunting ie revs going up and down and stalled under load at traffic lights if i turn the aircon off it improved so i replacd the vacume hoses and removed the throttle body and cleaned out the inlet. it ran like crap if you touched the throttle it stalled and at idle the revs went from 800 to 1800. So i remoed the throttle body again and the gasket fell apart so i used instant gasket put it all back together crossed my fingers and it went like a rocket. with the cruise on at 50 it would surge and made me feel sick so i went back to foot on the throttle and it was fine. that was yesterday. went to the supermarket all was fine when i went to leave it started messing around again after a few min i got it home. Now its running rough and stalling again. After talking to my parts guy he said it might be the idlea air control valve but i have no idea where it is as my haynes manual sucks and at $150 its a lot of money for a maybe. any one got any ideas please as im going nuts. PS: the check engine light is not on and from my understanding there are no fault codes loged but i am probably wrong...

axion dan · 09-22-2009, 04:34 PM

Hey,the IAC is threaded at the bottom of the throttle body and has a 4 prong connector. Maybe this will help you find it. If you replace the IAC you need to set the pindle it should be in your book on how to do this.

UK-1991-Z28 · 09-22-2009, 06:06 PM

Hi thanks. Do you think the symptoms i am describing could be the IAC ?

bgmoss · 09-22-2009, 08:00 PM

Sounds like the MAF sensor to me. Can you scan it and see if it has code 34 (MAF low). THat's usually how they fail.

axion dan · 09-22-2009, 08:45 PM

1991 didn't have a MAF sensor.