2008 .... rough idle

[BigRed76]

I looked at a 2008 XL Denali today which was in perfect condition 31k miles but had a little rough idle when in park. Can someone tell me what could be the possible cause of this? I asked the seller to bring it to the dealer and have it looked at before I would consider it. Any ideas?

 

[mlwald79]

my denali idles rough sometimes even with 93 octane. i am gonna try cleaning the throttle body and see if that helps.

 

[Modded]

Thats a commom complaint on the 6.2L engine models (like the Denali), try cleaning the throttle and see if it helps, def. won't get rid of it though.

 

[m332is]

My 2008 Denali does that as well. I really hate this answer, but they all do that. But step on the gas and it goes like a ***** ape however

Vince

 

[BigRed76]

well I passed on that truck and am glad I did .... Just put a deposit on a loaded 08' XL Denali with 19k miles

 

[jetfn62]

Dont bother cleaning the throtle body the 6.2 just runs rough at idle. I bought my denali crew 2008 new...rough idle since day 1...brought it in 5 times for that and other reasons...always told that theres no message posted from gm on how to fix(correct me if im wrong, but arent mechanics supposed to figure out a problems cause and fix it!!! Not wait for it to be written down in front of them before they know how to take action)...my suspicion is the computer is not fast enough to keep up with engine data???...what ever it is, as usual gm isnt going to take responsability and fix it...other problems with this model included 2 trips for leaky sun roof...and 5 new door handles that keep breaking. And i baby this thing!!! (just turned 18k miles-garage kept)

---------- Post added at 05:40 PM ---------- Previous post was at 05:34 PM ----------

 

[KMeloney]

My '09 idles rough as well. I cleaned the TB, and there was no change.

What's worse is that mine developed this problem -- it didn't start out that way. I'd say that after 2 years it developed this issue.

Oh -- and mine's a 5.3, not a 6.2. So, it's not even just a 6.2 thing. I think there's something else going on...

 

[Faceplant]

My 5.3 has done it since I bought it used with 50k. Bro in laws does the same thing. ******* GM quality.....

 

[ChrisAU]

My 5.3 does it as well.

 

[KMeloney]

Thats 9 trucks that do this in barely a 2 page thread? Is there any explanation from GM on this?

I've heard some people report some nonsense about the idle changing to compensate for temperature or other changes. Whatever it was specifically, it was complete crap. Yes, it may be true that these trucks do that -- but why? None of my other vehicles have ever done that.