Rough idling 07 Yukon Denali...

[livingez_123]

It sounds like it's time for GM to get a tune put together and a recall to fix this issue. it seems more people than not are having this issue. GM working on the problem? I really don't see them doing anything about it. The trucks are 7 years old, out of warranty, and they have other things to worry about.

 

[harveje]

I'd like to know why and what the root cause is. It's just friggin annoying.

 

[Rosko]

I don't think I'm going to worry about it unless it causes a major problem. Right now, it's a tiny bit annoying at idle, but it doesn't affect it much (never drops below 500rpm), and runs perfectly, responsive, has gobs of power.

I'm guessing others must have bigger issues than I do, and maybe mine will progress to that, until then I guess I'll wait.

 

[livingez_123]

I wonder if it could be as simple as raising the idle speed up 50-100 rpm.

I know when I tuned my Denali I changed all of the idle settings.

 

[harveje]

I'd like to try a tune but have not pulled he trigger. I raised my rpms temporarily with a tech 2 but still had the erratic shimmy,sputter,twitch whatever it is. It feels worst in the passenger set than the drivers. I may see if I can put some rubber or something where the seats mount down. Engine mounts look good. I guess not knowing the cause is driving me crazy. OCD I guess. And I guess I expect better.

 

[08grey]

Try marvel mystery oil mixed in with a full tank, mix as per instructions. Fixed my studder. I use it every full up.

 

[GM Customer Service]

Rosko,

Hey there! I understand that you are experiencing a vehicle issue that is annoying you. I might not be able to give you any technical advice but if you find that this may be a major concern, I would be happy to look into this concern for you. I am only a private message away!

Jennifer T.
GM Customer Care

 

[992dr]

I believe that the DOD/AFM is the culprit.
It was introduced in 07, correct?

 

[Rosko]

I believe that the DOD/AFM is the culprit.
It was introduced in 07, correct?

Not on the 6.2L, and I actually think it's more common there from what I've read.

 

[daddyrim]

Any updates on this?
Had my 08 Denali XL to the dealer for this twice. They say its normal for the 6.2 to have a rough idle? I kept explaining that it started getting worse about a year ago, and we never had that issue before. Dealer shrugs it off as I believe they have no clue what the problem is. No codes, no issue in their mind?

 

[Rosko]

I still have the issue. It hasn't gotten much worse for me, I have 90k now. Still aggravating/annoying but hasn't stalled on me yet.

 

[08grey]

Try some marvel mystery oil mixed with your fuel.

 

[Rosko]

I figured I'd revive this thread because it seems that I've found at least a temporary fix to the rough idle issue.

A few weeks ago my Denali was taking longer than normal to start, maybe 10s of the starter turning before it would kick over. After a week or so it finally threw the P0340 code and check engine light came on. The next day the light was off, it started fine...and continued to start fine for a few days.

I decided to buy a camshaft position sensor (NOT crankshaft), and had the dealer install it. So far, it hasn't had any issue starting and my idle is COMPLETELY stable....I mean, it doesn't feel like it's misfiring, doesn't "bump".....feels exactly like I'd expect it to, smooth and responsive. It also seemed to get rid of the tiny lag it had when you'd release your foot from the brake, and hit the gas.

It's only been a few days...but so far it's been pretty noticeable. I hope it continues to run this way and proves to be a permanent fix.

 

[992dr]

I had a pretty choppy/rough idle, only while in park or stopped.

I recently cleaned my TB and that has really smoothed it out.
Its worth a try

 

[Rosko]

I had a pretty choppy/rough idle, only while in park or stopped.

I recently cleaned my TB and that has really smoothed it out.
Its worth a try

Weird, so my rough idle was much more noticeable when I was in gear with the brake on, at a stoplight or stop sign. You could feel it almost pushing/lurching a bit in what felt like a misfire...caused vibrations etc, but it's all gone now.

I haven't cleaned the TB in 2yrs, I'll probably do that next along with some 100k mile maint.