IAC issue and surging
IAC issue and surging Mods in sig:
100% STOCK Tuning
200+ miles since cam in stall.
IAC counts at 189 deg oil temp
690-725rpm Idle speed
IAC(AC Off) = 15-18
IAC(AC On) = 30-32
I've recently been getting some surging and stalling after a warm start <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" /> . Normal driving is fine, buy if I stop at a store, shut it off, and then re-start, I start running in to problems.
After restart, the engine hits right around 700-725rpm and does not hunt for idle. Throw it in reverse, back out and then hit the brake. This is when it dies. Now the surging/hunting for idle starts. If I start moving then brake it dies. Once I get moving it seems to be fine. After a several minute drive I can stop and then move without a problem.
Checked a-tap and everything seems fine with the exception of the IAC counts, which seem abnormally low. Cold start there both over 100, but as the vehicle warms up, they go down, as low as the 15-18/30-32 at full operating temp.
TB hole has been drilled... Think its too big?
I also have performed a PCV mod, infcluding a filter. Would a partial blockage of the PCV system, have any effect on the IAC counts or surging/stalling issues.
Any help or other things to check would be greatly appreciated.
100% STOCK Tuning
200+ miles since cam in stall.
IAC counts at 189 deg oil temp
690-725rpm Idle speed
IAC(AC Off) = 15-18
IAC(AC On) = 30-32
I've recently been getting some surging and stalling after a warm start <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" /> . Normal driving is fine, buy if I stop at a store, shut it off, and then re-start, I start running in to problems.
After restart, the engine hits right around 700-725rpm and does not hunt for idle. Throw it in reverse, back out and then hit the brake. This is when it dies. Now the surging/hunting for idle starts. If I start moving then brake it dies. Once I get moving it seems to be fine. After a several minute drive I can stop and then move without a problem.
Checked a-tap and everything seems fine with the exception of the IAC counts, which seem abnormally low. Cold start there both over 100, but as the vehicle warms up, they go down, as low as the 15-18/30-32 at full operating temp.
TB hole has been drilled... Think its too big?
I also have performed a PCV mod, infcluding a filter. Would a partial blockage of the PCV system, have any effect on the IAC counts or surging/stalling issues.
Any help or other things to check would be greatly appreciated.
Re: IAC issue and surging The best way to get rid of this problem is tuning. There is a table in your car that controls airflow through the IAC. The hotter your car, the less airflow it admits. This is why your car runs fine cold but chokes and dies when it is warm.
The 'old school' solution to your problem is to drill your TB hole more. Unfortunately, it sounds like your car runs 'right' most of the time. If you drill your TB more the car will probably idle correctly all the time, but you are going to run into the dreaded "auto-roll" or "RPM creep" (where your RPM will stay at 2500 at the stoplight). Both of these are from too much air getting in at low RPM.
To completely fix your problem to get your car to run how it did before the cam then you are going to have to get it tuned.
Good Luck,
Kevin
The 'old school' solution to your problem is to drill your TB hole more. Unfortunately, it sounds like your car runs 'right' most of the time. If you drill your TB more the car will probably idle correctly all the time, but you are going to run into the dreaded "auto-roll" or "RPM creep" (where your RPM will stay at 2500 at the stoplight). Both of these are from too much air getting in at low RPM.
To completely fix your problem to get your car to run how it did before the cam then you are going to have to get it tuned.
Good Luck,
Kevin
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Joined: Nov 2001
Posts: 1,975
Likes: 2
From: SW Florida
Re: IAC issue and surging I am not an expert at PCM issues at all, but this is what Geoff at Thunder told me:
He said the IAC count with the engine at normal operating temp, idling, with the A/C off should ideally be around 15-25
He said if it was at 0, the hole in the TB was too big.
My PCM was shipped to him a couple of days ago for some tweeking. I had some of the same issues as you in my A4 car.
Ron,
He said the IAC count with the engine at normal operating temp, idling, with the A/C off should ideally be around 15-25
He said if it was at 0, the hole in the TB was too big.
My PCM was shipped to him a couple of days ago for some tweeking. I had some of the same issues as you in my A4 car.
Ron,
Re: IAC issue and surging Thanks for the input. I'll probably have to just deal with it for now. I need to get headers first, then the tuning... no need to pay for it twice.
Mike
Mike
