Stumped! So my car has been stalling on cold starts when i shift to reverse. I was reading about cleaning the IAC might help. So i decide to do that, and i did the whole cleaning process and screwed the IAC back on. Now the car has a really ugly idle, and wont stay on unless i leave my foot on the gas. Do i have to adjust something, is there something im missing? Maybe i have to screw the pintle more in or out? Please help

 

have you reset your IACV.. Follow this link

http://www.iroczone.com/2009/10/clea...rol-iac-valve/

Let me know if this works

 

https://www.thirdgen.org/tpimod2

 

If this is the stock GM IAC and you manually threaded the pintle out then back in you need a new one. The shaft has a slot in it that is keyed to the bushing it rides in. Manually rotating the pintle shears the keys out of the bushing.

So now the IAC will step but not properly extend or retract.

RBob.

 

So i followed your advice since i thought maybe i should replace the IAC with a new one since maybe its time for a new one anyways. So the car turned on and stays on. But now the idle is really high compared to how it was before. Is there something i need to adjust or will it adjust by itself?

 

There is an IAC reset procedure in the ECM. For the '8746, IIRC, start the engine, hold the throttle open a little, let off the throttle and key-off for at least 10 seconds. At key-off the ECM will run the IAC fully extended then retract it to the park position.

At that time the IAC position and ECM are sync'd up.

If the idle stays high after this there may be a vacuum leak. Be sure that the stock 195 thermostat is in place and that it is OK. IOW, the coolant temperature is reaching 195+.

RBob.

 

Cool so i did the whole reset procedure and it idles high when its cold like around 2000 but settles around 1500 when warm in park. Its still a bit high i think but i read somewhere that youre suppose to drive the car around at 40 mph so the ecm can learn the new iac? I hope im right but either way ill keep posted! Thanks for the help guys

 

im wondering if you disturbed the base gasket when messing with the iac. i would put in a new base gasket. then do what i posted in post number 3

 

I wonder if the tach is off, that is common in our cars. There is a sticky on the electronics board here on how to fix the tach.

At 1500 RPM in park it would slam into drive or reverse, and the car would be moving without go-pedal input.

RBob.