IAC Adjustment on a TPI

[The Fixer]

I've read the procedure over at www.thirdgen.org and it's simple enough. My question is this; should the adjustment be done when the car is cold and in open loop, or after it's been up to operating temperature and in closed loop?

[Ian]

the IAC operates the same in both open loop and closed loop, so I would think if wouldnt matter.

[Fasterthanyou]

Set the min idle with the IAC closed and the engine warmed up. When the engine is cold, the IAC is commanded to open more and won't let the motor stall. Setting it CAN be done with it running. Just hook up a scan tool and set the min idle watching the desired RPM, actual RPM, and IAC step counts. With TPI dry flow the IAC counts aren't all the important but I'd aim for 20-40 counts at idle, also get your TPS voltage below 0.65v.

[Ian]

damn, I suck! I should just wait until AFTER jon posts so I dont sound so dumb

[HardcoreZ28]

I can vouch for Jon's IAC count numbers....got my car all straightened out on friday....thanks again

[Fasterthanyou]

Originally Posted by Ian

damn, I suck! I should just wait until AFTER jon posts so I dont sound so dumb

I've studied thirdgens all my driving life if that makes you feel any better.

[The Fixer]

Originally Posted by Fasterthanyou

Set the min idle with the IAC closed and the engine warmed up. When the engine is cold, the IAC is commanded to open more and won't let the motor stall. Setting it CAN be done with it running. Just hook up a scan tool and set the min idle watching the desired RPM, actual RPM, and IAC step counts. With TPI dry flow the IAC counts aren't all the important but I'd aim for 20-40 counts at idle, also get your TPS voltage below 0.65v.

This sounds good, and I have a scantool. So, my plan would be to:

- warm the car up

- shut the car down, then turn the key on to let the IAC extend

- pull the plug on the IAC, then start the car

- adjust the idle according to the scanner (using the setscrew on the TB?)

Hopefully this'll do it. I'm trying to cure a stalling/stumbling problem when the car is cold. It will start fine, then the idle will go south and stall. If I keep pedaling it to have it stay running, it will pop back through the intake sometimes. Once the temp has come up a bit, it's fine. Any other thoughts?

[Fasterthanyou]

You said it idles poorely when cold and stalls... sometimes backfires, that's a lean condition. The scanner will tell you with BLM's above 128. This was paul's problem, well that and the fact that it couldn't "get it's learn on" because of too high a min idle. It was so weird, never had so much trouble with an idle. Thank's Paul.

[HardcoreZ28]

Haha no problem pal.....we'll just chalk it up to a learning experience.