Why do A6 08 LS3 Corvettes idle poorly?

**Larry** · 05-10-2008, 05:04 AM

I am in the market for an 08 LS3 automatic Z51. I've test driven three and idle quality is bad enough that I'm not going to spend over $50K for a car that runs no better than this. From idle in neutral to about 1500 rpm I detect a random misfire or sputtering. Moving in 6th gear light throttle in the 1200-1400 rpm range you can feel this misfire. It's not cam lope. I know cam lope. Does anyone with an A6 08 have this problem?

**7camaro7** · 05-10-2008, 09:24 PM

never driven one, but I personally wouldn't care about "idle quality" I'd just want it to be fast as hell hahahaha. Chances are the car you drove was probably not broken in all the way too, you think that may be the problem?

**vetteemt** · 05-15-2008, 08:26 AM

Being a new car, it might be that the computer has not learned enough about what timing and fuel setting it wants to have. During the learning program in the ECU you can experience some odd idles and can see this for about the first 200 miles or so. Tho it does not seem right this would be normal on an undriven new car.

**Larry** · 05-15-2008, 08:31 AM

Originally Posted by vetteemt

Being a new car, it might be that the computer has not learned enough about what timing and fuel setting it wants to have. During the learning program in the ECU you can experience some odd idles and can see this for about the first 200 miles or so. Tho it does not seem right this would be normal on an undriven new car.

Test drove a used 08 vette last night with 6400 miles and had the same misfire from idle up to about 1400/1500 rpm in neutral and very light throttle moving in 6th with converter locked.

**vetteemt** · 05-15-2008, 10:57 AM

Originally Posted by Larry

Test drove a used 08 vette last night with 6400 miles and had the same misfire from idle up to about 1400/1500 rpm in neutral and very light throttle moving in 6th with converter locked.

It might just be how GM has the computer tuned from the factory. They have to worry about emissions and other things that aftermarket tuners don't have too. I'm not saying that they did it because of emissions, but you might want to check with some of the dyno tuners to see if they have seen this and if they have been able to eliminate it. If you plan on mods then you’ll be getting a dyno tune most likely anyways.

**Larry** · 05-15-2008, 01:54 PM

Originally Posted by vetteemt

It might just be how GM has the computer tuned from the factory. They have to worry about emissions and other things that aftermarket tuners don't have too. I'm not saying that they did it because of emissions, but you might want to check with some of the dyno tuners to see if they have seen this and if they have been able to eliminate it. If you plan on mods then you’ll be getting a dyno tune most likely anyways.

I think you are right, it's in GMs tuning. However not sure it can be tuned out. Talked to one tuner and he said he has not been able to tune it out. Apparently most Corvette owners are not dialed into their cars enough to even notice this. It's not terribly bad as I mentioned but still a misfire is evident.

**vetteemt** · 05-16-2008, 04:05 AM

Originally Posted by Larry

I think you are right, it's in GMs tuning. However not sure it can be tuned out. Talked to one tuner and he said he has not been able to tune it out. Apparently most Corvette owners are not dialed into their cars enough to even notice this. It's not terribly bad as I mentioned but still a misfire is evident.

LOL Corvette owners not dialed into their cars

I'm in my local Corvette club and it always gets me when some of the newer c5 and c6 vette owners know nothing about there cars. After building my SS Lsx engine up I would give most advice on parts to use were to get a tune done etc.. and they always argue with me that the engine in my Camaro is different then the Corvette version (LS1 is a LS1 LS6 is a LS6 etc) Which I’d ask how and the normal response is I don’t know but the Corvette version must be better then the Camaro version. Also if you buy a 08 you could always put in a bigger cam which will give you a lopey idle and misfires would be normal then. This would not fix the problem but would give a good excuse to why its misfiring??

**stanger88** · 05-16-2008, 06:37 PM

Originally Posted by Larry

I think you are right, it's in GMs tuning. However not sure it can be tuned out. Talked to one tuner and he said he has not been able to tune it out. Apparently most Corvette owners are not dialed into their cars enough to even notice this. It's not terribly bad as I mentioned but still a misfire is evident.

Anyone who buys a 'vette is not nit-picking for quality. THey buy it for the looks, power, or stigma. I have NOT YET seen ONE C6 that didn't have trash in the paint down to the metal in a visible area or have a body-panel misalignment issue with the headlights/front end. We aren't talking micrometer measurements, we are talking I saw where they ground a panel down and painted clear over it on one side and the other stuck up 1/3 inch from flush. We are talking backyard mechanic front-end job type quality. I am very impressed with the driveline and suspension, but the body work/QC makes me gag.