Rough Idle on Denali

Does anyone else have a rough idle on their Denali? Are the RPMs supposed to noticeably fluctuate at idle? Given all of the computer controls and my experiences with other vehicles/engines, it seems as though the idle should be smooth and without fluctuation.

Thanks for any input.

I've got a black on black '07 Denali and it idles smooth as butter. When the engine gets up to temp the tac is pegged at the 500 rpm mark and doesn't move unless I hit the gas. Does your engine light ever come on or do you have any DIC warnings flash?

Thanks for the response. I wish mine was the same. However, I don’t have any warning lights on. The engine just seems to skip a beat every couple of seconds and the tack fluctuates. I am going to take it back into the dealer soon, but I suspect I will get the standard “If there are no codes or lights on, nothing is wrong†when I know the engine should run smooth.

Any thoughts on what I should look for?

Thanks

GMCYukonDenali said:

Any thoughts on what I should look for?

Thanks

Click to expand...

Dirty injector? Coil pack? Plug wire? Spark plug? You didn't say how many miles you had on it. First thing I'd try if dealer can't/won't help is to run a couple of bottles of Techron thru it. Do dealers still have ignition analyzer scopes? If you are getting a misfire condition, you should get a code, but that would also set the check engine lite.

Thanks. The Denali has about 4,000 miles on it, and the inconsistent/rough idle has been present from the beginning. I am perplexed too concerning the codes and lights—why hasn’t anything lit up? You guys are leading me to believe that I am somehow making this up, but when I see the tack bounce, that doesn’t seem right.

I appreciate all of the comments and suggestions you guys have posted thus far. Is there any condition that you could think of that wouldn’t trip the service engine light?

I know we have the 5 year/100,000 mile power train warranty, but I would like to get this fixed, as I am sure everyone can understand with a $50K vehicle.

Thanks again.

Can you hear/feel anything like the engine is actually missing intermittently? If not, maybe there's something going on with the tach. Just a thought. Also listen to the exhaust when idling, if missing, should be able to hear it there.