Cold start question
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Intermediate
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Cold start question
Just wondering why my c6 doesn't really have a "cold start". Car can sit for days & after starting doesn't idle up like normal to get the cats up to temp. Should I be looking at IAT sensor or coolant temperature sensor? Or is this normal on the ls2 to not have a cold start? I am new to the ls family so not sure if this is normal. I do have a cat back & I have not had the pleasure of hearing this thing cold start. Any ideas are appreciated
Melting Slicks
Joined: Oct 2022
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From: Ulta Vista, AZ
It should. I haven’t seen a car that doesn’t,
Could the car have been tuned prior and maybe the tuner removed the cold start enrichment and idle up? Seems illogical, but spit balling.
I would venture to guess your iacv determines this rpm ramp up for a cold start.
Could the car have been tuned prior and maybe the tuner removed the cold start enrichment and idle up? Seems illogical, but spit balling.
I would venture to guess your iacv determines this rpm ramp up for a cold start.
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Intermediate
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I do not know if it's been tuned by previous owners. The last guy that had it wasn't really into cars that much so I highly doubt he did anything to it. I don't really know why someone would tune that out but leave the cats on. It does have a cat back system & I've seen the cats. I'll have to look into the idle air control valve. Probably cheap enough to just replace.
Safety Car
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From: Etobicoke (Toronto) Ontario
My LS3 cold starts and immediately settles at 650 rpm, to the best that I can read the tac. There’s no fast idle. Same when I’ve run it for hours. No difference in start up idle.
Melting Slicks
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From: Ulta Vista, AZ
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From: Cape Coral, Florida
Just wondering why my c6 doesn't really have a "cold start". Car can sit for days & after starting doesn't idle up like normal to get the cats up to temp. Should I be looking at IAT sensor or coolant temperature sensor? Or is this normal on the ls2 to not have a cold start? I am new to the ls family so not sure if this is normal. I do have a cat back & I have not had the pleasure of hearing this thing cold start. Any ideas are appreciated
Last edited by C5 Diag; Jun 16, 2024 at 08:02 PM.
Safety Car
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From: Etobicoke (Toronto) Ontario
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Intermediate
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The only "cold start" would be the ECT sensor...the colder it is the ECM will increase injector pulse width...what do you expect to hear on a cold start ???...if you have a scan tool look at your ECT after the car sits overnight...ECT and ambient temperature should be fairly close to one another...look at global or generic OBD2...the temperature you will see will be what the ECM is seeing...there is something called "substituted values" which is like a default value that the ECM may use if the sensor is reading incorrectly...it can't use these substituted values in Global OBD2.
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From: Database Error Indiana
Its not going to happen. The ECM is not going make it idle any faster than needed.
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do you think that's odd? I've owned so many cars from imports to domestics. Maserati to Honda. Every single motor whether v8 v6 or i4 have warm up periods for the catalytic converters. Even in the summer when temperatures are 100 here in northern Indiana. They all had warm up periods.
Safety Car
Joined: Aug 2017
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From: Etobicoke (Toronto) Ontario
do you think that's odd? I've owned so many cars from imports to domestics. Maserati to Honda. Every single motor whether v8 v6 or i4 have warm up periods for the catalytic converters. Even in the summer when temperatures are 100 here in northern Indiana. They all had warm up periods.
Burning Brakes
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2023 C6 of the Year Finalist - Unmodified
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Melting Slicks
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From: Ulta Vista, AZ
When it’s warm mine barely does it. When it’s cooler it will do it and for longer when cold.
it all runs off the ect sensor if memory serves
Melting Slicks
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From: Klein TX
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I do not know if it's been tuned by previous owners. The last guy that had it wasn't really into cars that much so I highly doubt he did anything to it. I don't really know why someone would tune that out but leave the cats on. It does have a cat back system & I've seen the cats. I'll have to look into the idle air control valve. Probably cheap enough to just replace.
Melting Slicks
Joined: Oct 2022
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From: Ulta Vista, AZ
I am going to assume you are being a smartass for the guys that know cars, just don’t know LS engines.
You could have just said LS engines do not have an iacv.
Any other car the iacv coupled with the ect sensor would control this feature.
You could have just said LS engines do not have an iacv.
Any other car the iacv coupled with the ect sensor would control this feature.
Racer
Joined: May 2024
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I love my 2013 GS my cold start (FBO)..made my 79 year old mother jump when she was standing next to it in the garage and I started it up for her (she was visiting from out-of-state and it was her first time seeing my car). Wish I had got that on video. 
Last edited by Save the Manuals; Jun 18, 2024 at 11:52 AM.
