Rough idle 2011 GS
Thread Starter
Advanced
Joined: Oct 2011
Posts: 51
Likes: 2
Rough idle 2011 GS
My new GS has idled rough since the day I drove it away from the Dealership 200 miles away from home. I took it to my local Chevy dealer at around 1,200 miles and they said the computer shows nothing is wrong. It always idles rough (sometimes really bad), cold start or warmed up doesn't seem to matter. Anyone else have this problem and if so how did you get it fixed?
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,703
From: Far NW 'burbs of Chicago
St. Jude Donor '13
How rough is rough?
Our 2009 LS3 idles noticably rougher than our 2006 LS2 did, and that's typical. But overall, I wouldn't say it is rough on the grand scale of things.
Can you get a ride in another LS3 car?
Our 2009 LS3 idles noticably rougher than our 2006 LS2 did, and that's typical. But overall, I wouldn't say it is rough on the grand scale of things.
Can you get a ride in another LS3 car?
Pro
Joined: Jul 2011
Posts: 515
Likes: 1
From: Boca ARton FL
I think it is emission related on all new cars, my 11 Tundra has a rougher cold start idle than the 07 it replaced, my 11 Grandsport is rough til warm up but the grand prize winner is the 11 Infiniti GS37, it sounds like a Pro Stock for the first 2 minutes then it quiets down 
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,150
From: SW Florida
2021 C6 of the Year Finalist - Modified
I have a 2011 GS A6. It idled very smooth until I installed an aftermarket CAI.
Now, the idle is not as smooth as it was before. Most noticable when idleing in Drive and when the engine is not fully up to temp.
I am having a Chuck CoW tune done in a couple of days. Hopefully, he can tune out the slight roughness at idle.
Not really what I would call 'rough', but still noticable.
Now, the idle is not as smooth as it was before. Most noticable when idleing in Drive and when the engine is not fully up to temp.
I am having a Chuck CoW tune done in a couple of days. Hopefully, he can tune out the slight roughness at idle.
Not really what I would call 'rough', but still noticable.
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Drifting
Joined: Sep 2009
Posts: 1,606
Likes: 115
From: Chandler, AZ
when you go back to the dealer ask to sit in a couple others and just have them start up. you will be able to know right then if yours is different or not. if there is a big difference then obviously something is wrong, if not then just enjoy the feel of a beast under your butt.
Drifting
Joined: Jan 2006
Posts: 1,554
Likes: 158
Ok, most are saying that the 2011 Grand Sport idles rough. Tim said it is common with GS. I have a 2011 C6 436HP and I would not describe the idle as rough. Not Cadillac smooth but not rough either. Don't both models have the same LS3 engine with the only difference being the oil sump system. Just trying to understand why if the engines are the same why one model would tend to idle rough and not so much in non GS C6? What am I missing?
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,703
From: Far NW 'burbs of Chicago
St. Jude Donor '13
Ok, most are saying that the 2011 Grand Sport idles rough. Tim said it is common with GS. I have a 2011 C6 436HP and I would not describe the idle as rough. Not Cadillac smooth but not rough either. Don't both models have the same LS3 engine with the only difference being the oil sump system. Just trying to understand why if the engines are the same why one model would tend to idle rough and not so much in non GS C6? What am I missing?
The engines may be interchangable parts, but the people are not.
Racer
Joined: Jul 2009
Posts: 384
Likes: 2
From: Warrenville IL
My 09 LS3 did this when it was stock. It definitely has a small amount of cam "shake" to it at idle. It didn't do it all the time but often enough to notice.
