Idle issue
10-22-2013, 10:43 PM
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Idle issue so initially when i start the car everything is fine with the idle. once i turn the ac on it starts to bog out and want to turn off. here's the thing. if i start the car and drive for about 5 min to warm the car up then turn the a/c on everything is ok. but if i turn it on immediately after it will start the bogging.
10-23-2013, 09:26 AM
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ok so as i was reading I saw on a site it said to adjust the ac idle speed. anyone know how to do this? pics maybe where is the location? been looking online cant find exactly what i need thanks!!!
10-23-2013, 01:52 PM
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Commanded idle speed can only be adjusted via a PCM re-tune. You can force a higher idle speed by enlarging the TB air bleed hole, or by adjusting the blade set screw, but both of those methods will result in a higher idle under ALL conditions, and also some unwanted side-effects (idle hang/"cruise control effect", possibile high idle codes, etc).
Your engine was designed to idle properly, with all accessories running (including A/C), with the factory commanded idle speed. This is not the sort of thing that can fall out of adjustment. There is some other issue causing your engine to run roughly prior to warm up under the additional load of the A/C system.
I would start with a simple cleaning of the MAF, and any obvious areas for vacuum leaks (PCV system). If you have access to a scan tool, you can look at items such as fuel trims and O2 values during the condition (though it sounds like this problem is only happening during open loop). It would also be a good idea to check fuel pressure; if it's borderline low, then driveability issues might be more noticeable under conditions where the engine needs more fuel (cold start) and is also under greater load (A/C running).
Your engine was designed to idle properly, with all accessories running (including A/C), with the factory commanded idle speed. This is not the sort of thing that can fall out of adjustment. There is some other issue causing your engine to run roughly prior to warm up under the additional load of the A/C system.
I would start with a simple cleaning of the MAF, and any obvious areas for vacuum leaks (PCV system). If you have access to a scan tool, you can look at items such as fuel trims and O2 values during the condition (though it sounds like this problem is only happening during open loop). It would also be a good idea to check fuel pressure; if it's borderline low, then driveability issues might be more noticeable under conditions where the engine needs more fuel (cold start) and is also under greater load (A/C running).
10-29-2013, 07:46 AM
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so everything seems ok.. someone told me it may need a PCM tune today when i started it the rpm would go up to 1k then down to about 500rpm then up and down for about 3-5 min i had to apply gas to keep the car from shutting down. and I did not even turn the A/C on yet. ideas?
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10-29-2013, 09:55 AM
#10
Take the negative cable off the battery. I don't know the actual time for the idle relearn, but I usually leave it off for a few hours. Turn it back on, it wont want to idle more than likely. Once it's idling turn on all the accessories and let it idle for a while. Then go for a joy ride and break the dick off it.
I did it recently and it. It wants to die at first when you hit the throttle. My afr's were a little rich at WOT to start. The more you drive it the better it idles and the it'll get a solid wot AFR reading and run good if thats the issue.
I did it recently and it. It wants to die at first when you hit the throttle. My afr's were a little rich at WOT to start. The more you drive it the better it idles and the it'll get a solid wot AFR reading and run good if thats the issue.
10-29-2013, 11:13 AM
#11
You don't need a new PCM.....lol
You also do not need to do an idle relearn. An idle relearn is a 20 minute process.
When you start the engine when its cold the MAF is doing everything to regulate the engines idle.
Clean the MAF with MAF cleaner........spray the hell out of it and then also spray the IAT sensor in the lid. Just drench it........
That might fix the issue.
.
You also do not need to do an idle relearn. An idle relearn is a 20 minute process.
When you start the engine when its cold the MAF is doing everything to regulate the engines idle.
Clean the MAF with MAF cleaner........spray the hell out of it and then also spray the IAT sensor in the lid. Just drench it........
That might fix the issue.
.
10-29-2013, 12:10 PM
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so everything seems ok.. someone told me it may need a PCM tune today when i started it the rpm would go up to 1k then down to about 500rpm then up and down for about 3-5 min i had to apply gas to keep the car from shutting down. and I did not even turn the A/C on yet. ideas?
Idle surge on a stock engine is an indication of a problem. Might be an IAC issue, or vacuum leak, or poor sensor data, etc. Whatever it is, it seems to be getting worse since it's now happening without the A/C on as well.
A comprehensive OBD scanner would be helpful in this case.
10-29-2013, 01:23 PM
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Is your car modified in any way, beyond basic bolt-ons such as an air lid/catback, etc.? I ask because, unless you have some sort of significant modifications, you absolutely should not ever *need* a tune to get the engine to run and idle properly.
Idle surge on a stock engine is an indication of a problem. Might be an IAC issue, or vacuum leak, or poor sensor data, etc. Whatever it is, it seems to be getting worse since it's now happening without the A/C on as well.
A comprehensive OBD scanner would be helpful in this case.
Idle surge on a stock engine is an indication of a problem. Might be an IAC issue, or vacuum leak, or poor sensor data, etc. Whatever it is, it seems to be getting worse since it's now happening without the A/C on as well.
A comprehensive OBD scanner would be helpful in this case.
180 thermostat full exhaust stock end and heads also what is the average cost of a tune nowadays?
Last edited by BrainFreezE; 10-29-2013 at 02:09 PM.
10-29-2013, 02:54 PM
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There might not be anything wrong with the car at all, other than a poor tune.
Cam/intake/TB modifications add a whole new element to the potential causes for idle issues. These are important details to mention when looking for help with driveability issues.
Do you know the history of the build (who did it, specs on the cam, who tuned it, etc.)? Did it always behave this way since you've owned it? Did you do anything/change anything with the car prior to this issue popping up?
10-29-2013, 04:41 PM
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Well that changes everything then.
There might not be anything wrong with the car at all, other than a poor tune.
Cam/intake/TB modifications add a whole new element to the potential causes for idle issues. These are important details to mention when looking for help with driveability issues.
Do you know the history of the build (who did it, specs on the cam, who tuned it, etc.)? Did it always behave this way since you've owned it? Did you do anything/change anything with the car prior to this issue popping up?
There might not be anything wrong with the car at all, other than a poor tune.
Cam/intake/TB modifications add a whole new element to the potential causes for idle issues. These are important details to mention when looking for help with driveability issues.
Do you know the history of the build (who did it, specs on the cam, who tuned it, etc.)? Did it always behave this way since you've owned it? Did you do anything/change anything with the car prior to this issue popping up?
Cam (Comp 54-444-11 (XER273) 224/230 .581/.588 114)
Comp Magnum Pushrods
Comp 918 Valve Springs
F.A.S.T. 90 MM Intake Manifold
Nick Williams forged 90 MM Throttle Body
SLP Air Lid w/ K&N Filter
180* Thermostat
Pacesetter Coated Headers
Off-Road Y pipe
Corsa 3" Exhaust
10-29-2013, 08:48 PM
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Since the car is new to you, sounds like the best bet would be to have a good, experienced LS1 tuner look over the current tune and see if it can be improved, maybe do some general diagnostics with a comprehensive OBD scanner as well. You might have a hard parts issue (vacuum leak, etc.) or it might just be a poor tune. There are many variables when dealing with a modified setup like that, especially one that is new to you and may be the victim of stories you don't know about.
10-29-2013, 10:28 PM
#18
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yikes I hope not I just finally got a hold of the dude that sold me the car and said it is certain it will need a tune so guess I am going to have to do that.. anyone know what price range i should expect on a tune for my specifications?
