Brand new 2021 Denali shuddering

[Mike Diaferio]

I am not sure what all are talking about when it comes to rough idle. My 21 Denali was built in September 2020 and I now am just south of 18,000 miles. I have never experienced a rough idle at any time. I have never experienced a new engine running rough because they have to run lean! They are designed to run on the fuel they are expected to use. n the case of the Denali 6.2, you should be running premium fuel.

 

[cdgtahoe]

I have been running 93 octane fuel the whole time.

 

[Terry Hurlburt]

I have two Denalis, a 2014 and a 2018. Both with the 6.2 liter engine. Both engines have a slight “lope” to the idle that seems to be normal for this engine. I have asked the question at two different dealers and both said it was normal.
Interestingly the 2014 has had a super charger installed, bigger injectors to run E85, cat back exhaust and a custom tune to make max power. It still has the slight “lope” at idle.
Both vehicles have around 40000 miles now and seem to be doing just fine with routine maintenance.
Both are run on 93 octane regularly and of course E85 when I can get it.

 

[ddivinia]

Our 2022 Z71 tahoe doesn’t have auto stop. They paid me $50 since it didn’t have it. Heck, they should make it optional for people to delete that “featire“ for sure.

d.

 

[Quark]

Dealerships are known for putting the cheapest gas they can find in your new car. Next fill up use a top tier brand of gasoline and run it like you mean it.

 

[killjoy]

FWIW, my '21 AT4 is at the dealer getting all 16 lifters replaced. IME, the rough idle was very noticeable at stop lights... meaning you coast up to the light and stop, and the engine is trembling to the point it sounds/feels like it's going to stall. Tach blipping down below 300 RPM at idle, them blipping back to normal, then back down... like every second or two.

On mine, I think it was a exhaust lifter that went out, since it sounded like a popcorn popper under the hood. Cylinder was filling with gas/oil, then exploding into the exhaust manifold. Mine was may more than a typical lifter tap which is fairly quiet... this sounded like an exploding firecracker every second or two coming from directly under the intake manifold. Popcorn popper is the best description I give you. There was no debate/denying something wasn't right.... lol.

 

[JayBaywatch]

Hey there. I have a brand new 2023 Yukon Denali XL and I am experiencing what sounds like the same thing. I have about 1,500 miles on it and it just started happening today.

Did you ever figure out what it was?