Idle Rpms & Shake

txdox21 · January 31, 2011

I noticed recently that after my engine has been warmed up, and I stop at a traffic light, the RPMs will drop slightly, the truck will shake and then the RPMs will go back up. This cycle will continue approximately every 45 seconds.

I know I should take the truck into the dealership, but I hate my dealership, and I dont trust them.

I think I might try to clean the throttle body first, but with 15k on the odometer I wouldnt expect there to be a lot of carbon buildup.

BlackSilver · January 31, 2011

It's a new truck under warranty. Take the summabitch in and get it fixed.

redsled2007 · January 31, 2011

Sounds like a trip to the dealer for warranty! You do know that you do not HAVE TO take it back to the selling dealer? Any GM dealer will do.

MaverickZ71 · January 31, 2011

There are several prior posts on this topic. Some GM engines, the 5.3L in particular, seem to have a reputation for not always idling the smoothest. I read a review in a national automotive magazine back in 07 or 08 (still a GMT900) in which the reviewer said it was a great truck but he worried about the idle quality of the 5.3L engine. Maybe this is an AFM thing, I don't know. But I've learned that, for some reason, it is normal for the powertrain electronic nannies to jump your idle up and down a little at stoplights. You might try running some fuel with a little higher octane rating (mine likes the 'silver' or mid-grade fuel the best) and a couple of bottles of Chevron Techron fuel system cleaner (only additive recommended by GM) through it to see if that helps. If it is still running rough enough where you're not satisfied, you'll have to ask the dealer to fix it under warranty. When I inquired about it, my local dealer said "yeah, they all do that, as long as it doesn't die, there's nothing wrong." Good luck!

pilsner · January 31, 2011

Happens to my 2009 6.0L as well.

Just a rough idle is what everyone calls it. It dips about a needle width, or more.

cdb95z28 · January 31, 2011

There are several prior posts on this topic. Some GM engines, the 5.3L in particular, seem to have a reputation for not always idling the smoothest. I read a review in a national automotive magazine back in 07 or 08 (still a GMT900) in which the reviewer said it was a great truck but he worried about the idle quality of the 5.3L engine. Maybe this is an AFM thing, I don't know. But I've learned that, for some reason, it is normal for the powertrain electronic nannies to jump your idle up and down a little at stoplights. You might try running some fuel with a little higher octane rating (mine likes the 'silver' or mid-grade fuel the best) and a couple of bottles of Chevron Techron fuel system cleaner (only additive recommended by GM) through it to see if that helps. If it is still running rough enough where you're not satisfied, you'll have to ask the dealer to fix it under warranty. When I inquired about it, my local dealer said "yeah, they all do that, as long as it doesn't die, there's nothing wrong." Good luck!

I agree with this, My '09 Pontiac G8 GT 6.0L with AFM and my current '10 Sierra 5.3L with AFM both do this. Just learn to live with it and accept that it is the little idiosyncrasies of these engines.