2010 Denali Rough Idle

mike699 · August 31, 2010

I have a 2010 Sierra Denali with 3800 miles on it and I have been experiencing a rough idle condition almost all of the time. Sometimes it is worse than others. I took it to the dealer and they told me it was just the nature of the beast because no codes showed up on the Tech2 programmer. When I notice the rough idle I can usually see the tach bounce a little. I don't notice any issues at any other time so it may be just the nature of the lean fuel map. Does anyone have a 6.2 and experiencing similar symptoms? Should I be concerned or maybe try another dealer?

Thanks,

Mike

Jennabear · August 31, 2010

What type of fuel are you running?

mike699 · August 31, 2010

92 octane currently. I have tried 87 with a similar result.

mmccampbell · August 31, 2010

I have a 2010 Sierra Denali as well (4900 miles) and have not noticed any rough idling or "tach jumps".

Jennabear · August 31, 2010

92 octane currently. I have tried 87 with a similar result.

Could be bad quality gas, have you tried going to different gas stations?

mike699 · September 1, 2010

Yes, I have filled up at different stations over 400miles apart so I don't think the fuel is the problem. By the way on my last road trip I decided to see what kind of mileage I could get and actually got 19.6mpg going on average 3mph over the speed limit. So I was pretty pleased with that result. Now just to figure out this rough idle... Do you think running some Chevron Techron through would help anything?

[email protected] · September 1, 2010

If the tach's bouncing, it almost seems like a small vacuum leak. Maybe you need to get it smoked.

highspeedvehicle · September 1, 2010

Come to think of this I get this with my 6.2 at first start up in the morning. It does go away after 10-20 seconds though. There have been a few odd times when driving in heavy traffic it starts to vibrate but overall a smooth idle. Hopefully you can isolate yours and get it fixed.

Denali_Joe · September 8, 2010

from what I've gathered the 6.2 doesn't idle as smooth as other engines. I came from a tundra before the denali and I thought there was something wrong with it. When I got my blackbear tune, I was talking with Justin and he was telling me he thought it's the low idle on the engine that produces the not so smooth sensation. He cranked up the idle a couple hundred rpm's and it was super smooth. Justin told me his 6.0 ran real smooth and then he put heads on off of a 6.2 and along came the not so smooth idle. Apparently the 6.2 heads move a lot of air.

You mash on the gas and it goes, right? No stalling or sputtering? Just takes a little getting used to. I put a CAI on and cleaned the MAF, same idle. Sea Foam, no different, always run 91 or 93. Dealer found nothing wrong with truck. Bugged me for a little while, but I'm over it. Brakes work and accelerator does not stick either! Have not regretted going back to the GM truck once, only regret was getting the Tundra in 07 instead of the GM just to get rid of it in Feb 10!

semper3318 · July 18, 2011

Don't know if you've been lucky enough to figure out the rough idle or not yet? But I have the same thing with tach fluctuation and all. I have a 2010 crew cab Z71 with the 5.3. It's very aggravating because I haven't had any codes thrown. But the tach will dance from 500 to 700 RPM when at an idle sporadically. Did you ever find out what it could be?

Yes, I have filled up at different stations over 400miles apart so I don't think the fuel is the problem. By the way on my last road trip I decided to see what kind of mileage I could get and actually got 19.6mpg going on average 3mph over the speed limit. So I was pretty pleased with that result. Now just to figure out this rough idle... Do you think running some Chevron Techron through would help anything?