LS1 Cold start problem
12-02-2009, 01:57 PM
#1
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LS1 Cold start problem Over the past couple of months my car has been acting funny on cold starts (6-7+ hours of sitting). It will start normal, but then act like it is stumbling and will drop down to 8-900rpm, then surge quickly back to ~1700-1800rpm. It usually does this twice before it settles down to normal. Also, when it is revving itself up the exhaust sounds "crackly" or as if it is misfiring or otherwise running funny.
I know these aren't very good details, but it's on a 98 LS1 with full tune, 228/230 cam, etc.
Any advice is appreciated, can take a video if needed
I know these aren't very good details, but it's on a 98 LS1 with full tune, 228/230 cam, etc.
Any advice is appreciated, can take a video if needed
12-07-2009, 09:34 PM
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Not sure about the smoke, but also sometimes on warm starts the car will have trouble idling (starts fine, then rpms dip down really fast, lights flicker, etc. Then surges back up to normal). I had it checked for a vacuum leak and the mechanic said he didn't find one, but that does sound like the cause of my problem
12-07-2009, 10:42 PM
#6
Clean your MAF. Your MAF is what handles the engine on cold start up till it gets warmed up...then the 02 sensors take over.
Your MAF could wacky and causing your IAC valve to freak out. That would cause your rpm's to jump around until it gets warmed up.
Also, spray the **** outta the IAT sensor in the lid with the MAF cleaner while your at it.
Pretty cheap thing to try before you start really digging into it.
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Your MAF could wacky and causing your IAC valve to freak out. That would cause your rpm's to jump around until it gets warmed up.
Also, spray the **** outta the IAT sensor in the lid with the MAF cleaner while your at it.
Pretty cheap thing to try before you start really digging into it.
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12-07-2009, 11:09 PM
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MAF and IAT sensor for sure. Mine did the same thing and cleaned those and it stopped.
Exhaust is normal until its warmed up. Mine always pops when I shift until its warmed up.
Exhaust is normal until its warmed up. Mine always pops when I shift until its warmed up.
12-07-2009, 11:54 PM
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Clean your MAF. Your MAF is what handles the engine on cold start up till it gets warmed up...then the 02 sensors take over.
Your MAF could wacky and causing your IAC valve to freak out. That would cause your rpm's to jump around until it gets warmed up.
Also, spray the **** outta the IAT sensor in the lid with the MAF cleaner while your at it.
Pretty cheap thing to try before you start really digging into it.
.
Your MAF could wacky and causing your IAC valve to freak out. That would cause your rpm's to jump around until it gets warmed up.
Also, spray the **** outta the IAT sensor in the lid with the MAF cleaner while your at it.
Pretty cheap thing to try before you start really digging into it.
.
12-07-2009, 11:59 PM
#10
My MAF is disconnected and I don't use my 02 sensors either, I believe I have an SD or static tune of some sort. Can you diagnose a vacuum leak with a diagnostic tool such as AutoTap? I believe last time I was in the shop my IAC was stuck between 130-150 count, so I should probably replace that sensor
So your IAC is probably wigging out. Why...it could be anything from a failing IAC or a PCM problem to a short somewhere. Something is opening the IAC.
I don't know if a failing TPS sensor or IAT sensor can cause the IAC to freak out, but maybe.
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