2011 G37x, +/- 69k miles.

Smooth idle when I bought it in August, however once in a while would stumble at a stop light. By stumble, it would feel like it stalled then regain composure, didn't happen often. Also hesitated on initial acceleration.

Cleaned intake and MAFs, intake butterflies were filthy (post here). I disconnected battery during process but manually moving the butterflies upset the ECM as when I restarted the idle bounced (1500 to 1000 to 800 and back) and I got a CEL. Did the manual re-learn which cleared the CEL and seemed to correct the issue.

It's been about a week and I notice the idle is periodically rough (slight, but can feel the idle) and when it's like this I notice the idle is right at 500 RPM. When the idle is smooth, I notice it's above 500 and approximately where 650 RPM would be (by eye).

Should I do another re-learn? Car runs great, very responsive and powerful, with no other issues or CEL but is still running the Seafoam I put in the tank when I cleaned the intake.

Thoughts?

-Eric

 

You have a vacuum leak check all the lines for the intake

 

Sounds good!

-Eric

 

I do want to add to this: in park and reverse idle is +- 650 however in drive it's 500 and switching in and out of drive the idle changes.

-Eric

 

 

That's normal

 

Thank you!

500 RPM in drive is normal? Or different in reverse and drive?

Idle isn't terrible and most wouldn't notice, it is a little rougher than before I cleaned it.

-Eric

 

Idle in reverse vs park and drive are all diff but nothing above 800

 

I'll check for vacuum leaks around the throttle body tomorrow or Monday and then I'll probably do all the relearn processes again.

I just think it's weird it will idle at 650 in Reverse but not in Drive.

-Eric

 

I'll check for vacuum leaks around the throttle body tomorrow or Monday and then I'll probably do all the relearn processes again.

I just think it's weird it will idle at 650 in Reverse but not in Drive.

-Eric

 

Or maybe it corrected itself.

 

It does that because your engine is always spinning only your transmission doesn't

 

I know this is an old thread... but better than making a new one of the same scenario. I am having the same problem the OP, llebcire, is having. I bought an OBDII Bluetooth scanner using the Torque app and I got no error codes. The "rough" idle isn't continuous. It happens randomly but mostly from accelerating from a stop position. Not sure how to explain it... it gives an erky jerky feel like it is going to stall while accelerating (if that makes sense). Would a vacuum leak cause this as well? If it was a vacuum leak wouldn't the erky jerky feeling be all the time or not?

 

 

It is a 2011 G37xS Coupe - had it since 2012 - I have always used 93 octane from the same gas station

It is not idling rough continuous... can't really explain it... it like a jerky feeling from the engine in spurts.... I can go for about 2 mins before it does it again. Doesn't matter if I had just started the engine and then going down the road or after it has been running for awhile to where it has warmed up...