Anyone else having rough idle

[Robwcormack]

I've got less than 1000 miles on this thing and it started idling kinda rough today 

[eppieguy]

I've noticed a rough idle when I have the Auto Start / Stop turned off and I come to a stop, it's almost as if the truck wants to shut off but doesn't, then it smooths out a bit. 

[Sierra Dan]

Typical at times with AFM/DFM 

Plenty of topic discussion over on the K2 forum.

[Smitty]

I noticed the EXACT same thing...   I turned auto  ON \ OFF and the rough idle seemed to go away.   

[Jesus Garcia]

My 2019 GMC Sierra slt works perfect all morning with ac on, idle just above 500. In the afternoon idle goes up to 650 and I have a rough idle at that rpm.

[L.P.]

I have a 2019 silverado 6 cylinder  and it is modeling tough. Took it in with  8000miles and they said basically nothing is wrong. It wasn't running  like this when I bought it.

[BlancoSilverado]

Same issue until i used 89 & 91 octane.

Cleared it right up, i switched back for a tank and it came back. So at this point my truck (L84) likes 89 octane or better. I only use Chevron, Shell, 76 fuel, unless i need fuel and cant find any of those brands, at that point i use 91 octane. 

 

Try using one tank of 91 and see if it clears up( use 91 for one tank because it will mix with the 87 that you have in the tank).

[ct_corey]

Certain days while in drive my truck will idle SUPER rough. Ive tried different octanes and still does it. 

[RaisedByWolves]

Its the cylinder deactivation.

 

You can prove this to yourself by taking your foot off of the brake momentarily and you will notice it will stop.

[ct_corey]

10 minutes ago, RaisedByWolves said:

Its the cylinder deactivation.

 

You can prove this to yourself by taking your foot off of the brake momentarily and you will notice it will stop.

I don't think the cylinder deactivation happens at idle. 

[Ricomtzjr]

I purchased a 19 Silverado LT with the 2.7 turbo 4. I had the same hesitating issue at coming to a stop with 4,000 miles on it. Took it to the dealer, they said it was a transmission sensor. Waiting on said sensor to come in for repair. 

[Mjharden]

If it’s any consolation, I had a 2019 Ram that did the same thing. I now have a 2019 Trail Boss LT, and it will idle rough from time to time. I think it’s just a characteristic of these engines.

[hotrodz37]

21 hours ago, BlancoSilverado said:

Same issue until i used 89 & 91 octane.

Cleared it right up, i switched back for a tank and it came back. So at this point my truck (L84) likes 89 octane or better. I only use Chevron, Shell, 76 fuel, unless i need fuel and cant find any of those brands, at that point i use 91 octane. 

 

Try using one tank of 91 and see if it clears up( use 91 for one tank because it will mix with the 87 that you have in the tank).

 

I second this. My k2 idled rough from the day I got it, was driving me nuts since I sit in a lot of stop and go traffic. I switched to 89 octane and it that's all I ran in it for the last 5 years and it cleared it right up. Like above, only use top tier gas too. My new T1 Sierra is doing it, only have 200 miles on it and I feel the rough idle at stop lights etc - assuming the dealer put 87 in it. I'm going to switch to 89 and see how it does. Exact same motor so should clear it up. 

Edited December 6, 2019 by hotrodz37

[Artischain]

I don’t know if this will even be seen anymore, but I have a 2019 sierra SLT with 45k miles. I idle in park for hours every day at work, and the idle has been really rough recently even killing the truck once or twice per day. Any ideas?

[Anacortes Army Guy]

20 hours ago, Artischain said:

I don’t know if this will even be seen anymore, but I have a 2019 sierra SLT with 45k miles. I idle in park for hours every day at work, and the idle has been really rough recently even killing the truck once or twice per day. Any ideas?

I'm sure the more knowledgeable amongst the forum members will respond, but when I hear about rough idle issues I think things like dirty injectors or a bad spark plug, but I'm no automotive mechanic.