Cascade Crew

scott in wa. · Posted: Sun Dec 03, 2006 10:04 am Post subject: chip tuning

Well,
I was messing around with the car last night,
The problem is that the IAC opens way up after the car is ran a few miles.
I set the min air/ time it/ set TPS to .540 then after a few miles the darn thing sounds like a broken shop are hose sssssssssssssssssssssss
And the idle is way high, about 1800 rpms.
Time after time, I go through and re-set everything and bam it does it again.

It didn't do this before but its a hole different setup, 7730 computer with stealth ram and the huge Holley throttle body.

Any ideas???????

Thanks
Scott

Twilightoptics · Posted: Sun Dec 03, 2006 12:11 pm Post subject:

Sounds like wiring or something set in the chip. Lower your minimum IAC counts/rpm.

scott in wa. · Posted: Sun Dec 03, 2006 12:44 pm Post subject: yep

Ya, if I can today, I'll set the minimum IAC counts/rpm to zero all across the board just to see if it stays closed.
If I set it to zero it shouldn't move while driving right?
Thanks

Scott

Twilightoptics · Posted: Sun Dec 03, 2006 6:47 pm Post subject: Re: yep

scott in wa. · Posted: Mon Dec 04, 2006 7:21 am Post subject: oh ya

I changed all the counts to 30 on the iac stuff in the chip, left the park position at 160.
Hooked up the computer and ran it, was at 30, big difference in idle.
Before those changes it was at 160 at idle. So it looks like the iac is working correctly.
So I will have to go back and change them all back, about 4 different things back to where they were before the change. Then go and change one at a time and see what one makes a difference.

Would a bad o2 sensor do this to the iac?? What tells the computer to open the iac? Mat sensor????
I notice that when I stab the throttle the counts go up on the iac.
Cool

Scott

Twilightoptics · Posted: Mon Dec 04, 2006 8:14 am Post subject:

The counts always change when the thorttle moves. Wouldn't worry about it.

The computer opens/closes the IAC to control air coming in or to stop air from coming in... aswell as controlling the fuel that way.

Bad O2 makes your BLMS and your o2 readings bad so the computer tries to compensate off false information, which causes the engine to run even worse, which makes the ecm try to compensate more, etc etc.

Mangus · Posted: Wed Dec 06, 2006 9:21 am Post subject:

Your IAC is controlled based off of a number of factors, including TPS, target idle vs. current idle, temp, correctors (fan anticipate, A/C anticipate, P/S anticipate, etc), and a few other things.

Check to make sure you don't have a vacuum leak (which a hissing would indicate you might have), and go on thirdgen and search on "reset IAC". Keep in mind that IAC communication is one-way. The computer commands a count, but has no idea if the IAC is actually at that count. If the devices get out of sync, that could cause problems. A reset is the way to go to correct that.

After all else, pull the throttle body and clean up the IAC passage ways, pintle, etc.

Don't mess with the chip to correct for mechanical problems, of course.