Rough idle

[Doubeleive]

get a fuel injection service done or throw a couple bottles of injector cleaner in it for the next few fill up's this generally resolves it. I use injector cleaner in mine on a regular basis she idles smooth. Even when the ac kicks on it doesn't skip a beat

 

[BG1988]

I also forgot to ask, was it idling smooth before and now you notice a rough idle? You said that it seems the LS engines can have a rough idle even when new. If it was smooth and now rough, then that makes no sense as an excuse for what you are experiencing. I would at least pull the plugs and post pics here. You may have a fouled plug for some reason. Get a fuel pressure reading in drive and in park to compare, after engine is warm. I also forgot to ask, problem with cold or warm engine?

rough idle might be normal to an extent.... if it was misfiring the whole SUV would be shaking violently or the timing would go negative (retarded ignition timing) the CEL would be flashing.....

the rpm would drop and recover over and ever

or the engine stall out


a better way would be to check the live data stream data.. this will give more information... example at idle the converter converter temp would increase (at idle after warming up) as you will be burning fuel in the converter instead..

Less MPG

check for broken motor/transmission mounts etc..

 

[FrankU]

Did you check the gap on the plugs before the install ? They "say" the plugs are gaped at .40 and that wasn't the case when I changed the plugs.

 

[JBravo1977]

This sounds like the problem I'm having with my 2014 with 109k miles. Would a miss like that throw a code?

 

[OR VietVet]

Need to check with a scanner and see if has any history codes. History of tune related components, MAF and MAP, throttle body clean, check motor mounts....etc.

 

[wsteele]

This sounds like the problem I'm having with my 2014 with 109k miles. Would a miss like that throw a code?

Generally it will throw a code. A very slight and very occasional miss might only show up in the miss counter in a scanner and not store a code.