For the last month or two my 91 3.1 bird has had a code 35 (IAC malfunction). The car idles steadily at about 2k-2.5k in park and 1.5k in drive. When I first start the car it fires right up, no problem. But once I shut the engine off and try to start it back up (key on, engine off), all the lights come on the dash but the engine will not start. I'm thinking of trying an IAC adjustment but in the post it mentions using a paperclip as a jumper between the A and B ports in the ALDL connector and starting the engine with the IAC disconnected. I don't want to fry my ecm but would this cause the car even with the IAC disconnected to operate in "limp home mode"? Where is this torx screw on the side of the throttle body located? Here is the original post:

https://www.thirdgen.org/tpimod2

Any help would be appreciated, thanks!

 

Don't mess with the idle stop screw, at least not yet. Most likely need to clean the throttle body (TB) and IAC. The IAC may be bad but cleaning everything is first. The EGR dumps in right behind the throttle blade and makes a mess of the TB.

There is also an idle learn procedure that needs to be done. This is more important on an automatic car then one with a stick.

There is a thread on the V6 board that covers both the cleaning and idle learn. I'll find it and post the link here.

Note that the procedure you linked to isn't correct for the 3.1l V6 MPFI engines. It is for the early MAF TPI engines, right off the TPS isn't adjustable on the 3.1l engines.

RBob.

 

Link:

https://www.thirdgen.org/forums/v6/1...dle-learn.html

It also has information on troubleshooting code 35.

RBob.

 

Thanks for the info RBob. I removed the IAC valve and started the car and let it run and the pintle extended on it's own, I think it was an autozone (Duralast) one and the TPS is the same. I also checked for vacuum leaks with a vacuum gauge and it held steady between 19 and 20. I don't think my o2 sensor or EGR valve has ever been replaced, I had cleaned the throttle body itself pretty good earlier this year but if you think it needs a good cleaning again I'll pick up some carb cleaner and get in there real good again. I haven't done an idle learn procedure in awhile, usually when I start up the car from the moment it starts running the SES light stays on.