Iac?
Banned
Joined: Sep 2008
Posts: 0
From: tn
I know exactly how an IAC works. I guess I should have rephrased what I ment. It does help "stabilize" the idle but again it does not control it. You can delete the IAC all togather and the car will idle but do a WOT run and take your foot off the gas with out in and see what happens.
Our IAC's are step motor versions. Their are 125 steps in which they can change the seat position. That is controled by the ecm with pulses to the iac and each pulse is 1 step. If the IAC dies it will stay at the last step it was at so If it died at wot it will be stuck at wide open which will cause the hanging idle if it died at idle it will be stuck midway which will cause stalling.
And Steve is exactly right when he said the IAC controls the dashpot.
Our IAC's are step motor versions. Their are 125 steps in which they can change the seat position. That is controled by the ecm with pulses to the iac and each pulse is 1 step. If the IAC dies it will stay at the last step it was at so If it died at wot it will be stuck at wide open which will cause the hanging idle if it died at idle it will be stuck midway which will cause stalling.
And Steve is exactly right when he said the IAC controls the dashpot.
3rd Gear Member
Joined: Aug 2008
Posts: 912
From: Oklahoma
I have tuned a few cars, and I am tuning that lightning with the owner but I am a little rusty. I'm downloading some SCT updates so I can log in to Advantage, the IAC motor controls takes part in a few things
3rd Gear Member
Joined: Aug 2008
Posts: 912
From: Oklahoma
I know exactly how an IAC works. I guess I should have rephrased what I ment. It does help "stabilize" the idle but again it does not control it. You can delete the IAC all togather and the car will idle but do a WOT run and take your foot off the gas with out in and see what happens.
Our IAC's are step motor versions. Their are 125 steps in which they can change the seat position. That is controled by the ecm with pulses to the iac and each pulse is 1 step. If the IAC dies it will stay at the last step it was at so If it died at wot it will be stuck at wide open which will cause the hanging idle if it died at idle it will be stuck midway which will cause stalling.
And Steve is exactly right when he said the IAC controls the dashpot.
Our IAC's are step motor versions. Their are 125 steps in which they can change the seat position. That is controled by the ecm with pulses to the iac and each pulse is 1 step. If the IAC dies it will stay at the last step it was at so If it died at wot it will be stuck at wide open which will cause the hanging idle if it died at idle it will be stuck midway which will cause stalling.
And Steve is exactly right when he said the IAC controls the dashpot.
we are all on the right track so the OP should be informed by now
5th Gear Member
Joined: Mar 2007
Posts: 3,791
From: Cary/Charlotte, NC
Well they turned up the Idle Decay rate and the stopped idle was ok, still high but not that bad. The rolling idle was just way up there.
I don't exactly know how the SCT or CRM software is setup so I don't know what tables you would have to edit to accomplish this.
But when I asked about it, they said the car was having some idling problems that they attempted to correct.
I don't exactly know how the SCT or CRM software is setup so I don't know what tables you would have to edit to accomplish this.
But when I asked about it, they said the car was having some idling problems that they attempted to correct.
3rd Gear Member
Joined: Aug 2008
Posts: 912
From: Oklahoma
Well they turned up the Idle Decay rate and the stopped idle was ok, still high but not that bad. The rolling idle was just way up there.
I don't exactly know how the SCT or CRM software is setup so I don't know what tables you would have to edit to accomplish this.
But when I asked about it, they said the car was having some idling problems that they attempted to correct.
I don't exactly know how the SCT or CRM software is setup so I don't know what tables you would have to edit to accomplish this.
But when I asked about it, they said the car was having some idling problems that they attempted to correct.
AKA, they didn't know what they were doing...
I shouldn't say that... tuning a car at WOT is by far the easiest part. drive ability is the hard part. You tune might be really close and if the plate you installed fixed the idle problem I wouldn't worry about it.
Do you run a real A/F Gauge?
5th Gear Member
Joined: Mar 2007
Posts: 3,791
From: Cary/Charlotte, NC
Well I felt the same way about their competence....
So I took it to another shop. They did a baseline and they said the A/F was spot on but the Timing was pretty conservative.
They picked up 19 ft/lb down low which is a noticeable difference. But they didn't gain much up top.
They also fixed all of the problems I was having with the idle.
So I took it to another shop. They did a baseline and they said the A/F was spot on but the Timing was pretty conservative.
They picked up 19 ft/lb down low which is a noticeable difference. But they didn't gain much up top.
They also fixed all of the problems I was having with the idle.
Banned
Joined: Sep 2008
Posts: 0
From: tn
Deconfire you need to find a new tuner. The IAC lets in air acording to alot of other sensors (ECT, TPS, IAC, MAF, O2) so if the IAC was causing your crazy high idle something else was wrong. I would say that since it was idleing that high there is either to much fuel at idle or not enough timing.
