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Discussion Starter · #1 ·
2004 M6

Is there any re-learn / or re-set protocol that needs to be followed when replacing an IAC? Thanks!
 

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pea on mea
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there is no iac relear / reset.

are you talking about the tps ?

if so, you just unplug it, turn key
on to acc position for 10 seconds.
turn key off, plug it back in, and
you should be good.

are you having idle issues ?
 

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Discussion Starter · #3 ·
No, not the TPS.
I am having some throttle response issues. When I shift gears at higher rpm's, the throttle seems to "hang" for a second before dropping down. Also, the rpm's don't drop down to normal idle speed until about 1 second after coming to a complete stop. If I push the clutch in and coast, the idle stay at around 1100.

Just trying to identify the problem. New IAC is easy enough.

Already replaced maf, iac, O2's and the problem wont go away. car is stock. No CE warnings.
 

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Your tune is no-good and you need to find a competent tuner. Since you didn't complete your profile and your location is unknown, you're on your own.
 

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that does seem high for a rolling idle. i'll have to check what the stock setting is at when i get home.

as for the throttle hanging, can you describe more? there is a feul cut off when the clutch is depressed.
 

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Discussion Starter · #9 ·
Hey guys, just to clarify, the car is high mileage...188K.
The is no tune in the car. Completely stock except for a cat-back exhaust.
Additionally, I had brought the car to a local LS specialist, and he could not figure out what the issue is.
He suggested a re-flash directly from GM, which he performed, however it did not correct the issue.

He thought there might be a small intermittent vacuum leak, but could not find one. We left off with the recommendation that I continue to drive until the issue becomes more prevalent which should make it easier to identify. However, after a few months now, the problem doesn't seem to be getting any worse, but it is a major nuisance to drive the car under this condition.
 

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Discussion Starter · #10 · (Edited)
that does seem high for a rolling idle. i'll have to check what the stock setting is at when i get home.

as for the throttle hanging, can you describe more? there is a feul cut off when the clutch is depressed.
When I press the clutch and let off the throttle to shift gears, the rpm's will hang for a second or two before dropping off. If the weather is cold and the car is still on fast-idle after a cold start, the rpms will actually increase slightly before dropping off between gear changes. Another symptom is my fast idle is way too high on cold starts. Rpms will go to 1800-1900 for a few seconds before dropping down to a reasonable rpm. The higher the rpm I shift at, the longer the delay is in the rpms dropping off. Intrestingly, this only happens during a 1-2 or 2-3 shift. Does not occur on the 3-4 shift even under heavy throttle.
 

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Discussion Starter · #12 ·
A little back story on how this issue started if you guys are interested...Back in June, I was driving along in stop-n-go traffic and had a red light come up some distance in front of me. Let off the throttle, and the car continues to accelerate hard. really hard. Push the clutch in, and the rpms shoot up to around 5000 rpm. My instant though was the throttle linkage was jammed. I blipped the throttle a couple of times and that didn't bring the rpms down. Now I'm freaking out, so I just shut the engine off. I go to restart, needed to turn the engine over a lot more than necessary with the throttle to the floor to get her started again. For about 3 seconds after starting, she idled very high, then instantly just began to idle normally again.

So I get her home and my thought is that the IAC locked up. Check linkage for binding. No binding. Movement is smooth. Pull the IAC out and its covered in muck, as is the port that the pindle sits in. Cleaned everything up with some carb cleaner. Did a thorough job cleaning the pintle seat in the TB until all traces of muck were gone. Cleaned around the throttle blade too, though it wasn't that mucked up to begin with, Re-installed IAC. And everything was fine for a couple of days until the same sequence of events happened again.

So I figured time for a new IAC. Bought a cheapo from Ebay for like $10. Put it in and never had the same issue again, however, car starts showing the symptoms I am currently dealing with. (Poor throttle response) On the notion that the replacement IAC I purchased so cheaply might be junk (you usually get what you pay for) I bought another IAC which appears to be from a different manufacturer based on its visual features. Installed it. No change in throttle response. Same as the first replacement IAC.

Which brings me back to my opening statement...Did I need to perform any type of re-learn / re-set when I installed the IAC. It seems from your responses that the answer is no.

Is it possible that these Ebay IAC's are all junk? Should I get a OE piece from GM? Is this even related to the IAC? My head is spinning right now. I've replaced all of the parts that would usually cause this type of issue. (ECU re-flash, O2's, MAF, IAC, Coolant temp sensor, cleaned TB port / blade / IAC /pindle seat, check for vacuum leaks )
 

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i honestly would have no idea. it is a bosch system that interacts with the other electronics on the car, and i'm sure it can be accessed with a tech ii, but i'm just talking out of my tail here. if fox moulder is still around i am sure he would know.
 

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Discussion Starter · #16 ·
A few months ago I went into my tire shop to get a tire plugged and the guy there that I generally deal with mentioned he had a scanner and he'd take a look for me. He hooked the ECU up to some Snap-On scanner and the only thing he came up with was a radio-related code. A few weeks earlier, I had gotten an error on the radio display because the CD mechanism was having trouble switching discs. It amazing how much detail those scanners can pull out of the system.
 
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