Uncontrollable idle with A/C
Thread Starter
Teching In
Joined: May 2008
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From: PA
Uncontrollable idle with A/C Don't know if this is the right spot for this or not.
I have an 02 ss with 1800 miles on it. I installed a set of lt headers on it with all the air hook ups and high flow cats. I did a mail order pcm for the tuning. The car runs great with the new pcm installed until I turn on the A/C. When the A/C kicks on the car stumbles for a second and then comes back to normal idle, but as soon as I give it any gas it will rev up to btw 2500 to 3500 rpms and just hang there until I turn the A/C off. Once the A/C is off it will eventually return to normal idle after 15 or 20 seconds. Any one able to help with this??
I have an 02 ss with 1800 miles on it. I installed a set of lt headers on it with all the air hook ups and high flow cats. I did a mail order pcm for the tuning. The car runs great with the new pcm installed until I turn on the A/C. When the A/C kicks on the car stumbles for a second and then comes back to normal idle, but as soon as I give it any gas it will rev up to btw 2500 to 3500 rpms and just hang there until I turn the A/C off. Once the A/C is off it will eventually return to normal idle after 15 or 20 seconds. Any one able to help with this??
Thread Starter
Teching In
Joined: May 2008
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From: PA
I thought that as well, and I did send it back. The second pcm he sent does the exact same thing. I would not think the tune for this car should be very hard, since all it has is headers. Also I have put the stock pcm back in and the car does not exhibit the uncontrollable high idle with the A/C on. It does have a very rough idle with the stock pcm thought. I would suspect it would not idle correctly though with the stock pcm because of the changes made to the car.
sounds like a vacum leak. Check the lines on the back of the intake. Also if you trace the line back there is also a T-fitting on it that could have gotten pulled out while putting the headers in
Thread Starter
Teching In
Joined: May 2008
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From: PA
I checked all the vacuum lines and fittings, and they all seem to be fine. If it were a vacuum leak wouldn't it idle high all the time? Also why would the stock pcm not idle high?
Not always. I've had issues with vacum leaks where it would drive fine but the RPM's would just take forever to come back down. Maybe the IAC valve isn't tuned right. You can try disconecting the IAC on the throttle body and see if that makes a difference.
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I thought that as well, and I did send it back. The second pcm he sent does the exact same thing. I would not think the tune for this car should be very hard, since all it has is headers. Also I have put the stock pcm back in and the car does not exhibit the uncontrollable high idle with the A/C on. It does have a very rough idle with the stock pcm thought. I would suspect it would not idle correctly though with the stock pcm because of the changes made to the car.
Sorry for the cost you've expended, but it's time to cut your losses with Tuner #1 (try and get some money back) and go find another tuner. There are plenty of forum sponser tuners here who know what they are doing.
For the idle routines, there are separate tables for idle p/n, idle gear, idle AC p/n and idle AC gear. Sounds like something is wrong with the AC section.
Adding headers will not noticeably affect the tune. The car will just run rich, especially at WOT.
Thread Starter
Teching In
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From: PA
If you're saying you stuck the old PCM in and the problem went away, than it's definately the tune. No question.
Sorry for the cost you've expended, but it's time to cut your losses with Tuner #1 (try and get some money back) and go find another tuner. There are plenty of forum sponser tuners here who know what they are doing.
For the idle routines, there are separate tables for idle p/n, idle gear, idle AC p/n and idle AC gear. Sounds like something is wrong with the AC section.
Adding headers will not noticeably affect the tune. The car will just run rich, especially at WOT.
Sorry for the cost you've expended, but it's time to cut your losses with Tuner #1 (try and get some money back) and go find another tuner. There are plenty of forum sponser tuners here who know what they are doing.
For the idle routines, there are separate tables for idle p/n, idle gear, idle AC p/n and idle AC gear. Sounds like something is wrong with the AC section.
Adding headers will not noticeably affect the tune. The car will just run rich, especially at WOT.
Yes, that is correct, with the original stock pcm in the car runs as it always did. No. idle issues. Just to verify I just put the original pcm back in, and drove a few miles just to let it learn a bit, and the car runs fine, no high idle with the ac on.
I then put the new pcm in, and it went right back to an uncontrollable high idle with the ac on. It idles and runs fine with the ac off, but as soon as I turn on the ac it idles up to between 2500 to 3500 and just hangs there until I turn the ac off.
There are sections in your tune that are specifically tweaked for AC conditions and it sounds like these are bit off. It almost sounds like he forgot to tweak your "In Gear AC/Off" target idle to match or be close to your "In Gear AC/On" although symptoms don't exactly follow that.
How are you flashing your unit?
Do you have bin's you can upload?
Its been a while, I wonder if all bin's are the same. I don't think they are.
I don't think someone with HPTuners could read your before and after.
I was thinking if you could post it someone could look at the two and see what was missed.
I'd consider putting this ? in the PCM/Tuning section if you haven't already done so, or request a thread move.
How are you flashing your unit?
Do you have bin's you can upload?
Its been a while, I wonder if all bin's are the same. I don't think they are.
I don't think someone with HPTuners could read your before and after.
I was thinking if you could post it someone could look at the two and see what was missed.
I'd consider putting this ? in the PCM/Tuning section if you haven't already done so, or request a thread move.
without looking at the before and after tune files it's hard to say. But you have answered your own question, if the stock one works fine and the other is crazy the tuner screwed up.
