M3 idling rough...

[Ashbc]

Could it be down to a service??!!

[thekurgan]

More details man, more details.

Rough idle when cold
Rough idle when warm
Rough idle after a track session/driven hard
RPM indicator bouncing during the rough idle
Are there any codes?
How is the quality of your fuel?

[nthretourNAFTW]

^ What he said.

[SpacegrayMe90]

Don't mean to jack the thread, but I'm having some idle issues as well.

My idle is rough upon cold start. The idle is a little better once warmed up, but still noticeable and does not completely smooth out.

The RPM indicator does bounce during the cold start, and does it occasional while stopped at a light. It will just rev up and I'm like wtf is going with this car.

My car stalled two times in stop and go traffic this past Saturday. Kind of embarrassing.

Almost stalled as I was making a left with on coming traffic, I had to shift to neutral to keep it alive. Very scary moment.

No stalling Sunday or Monday Just the Idle is still erratic.

The only thing I remember doing Saturday prior to having stalling issues was turning on the AC, as it was damn near 80 degrees in NYC.

I use Shell V power religiously. I emptied the tank with multiple WOT pulls and then filled up with V-Power from another Shell station Saturday night.

[grantmax]

Originally Posted by Ashbc

Could it be down to a service??!!

Yes.

[vsix]

Hmmm...sound's like the BMW's in general do act sometime's funny when the weather get's warmer! Buddie's E92 335i idle's for a few second's irratic on cold start's, only when the weather temp's climb up.

[Ashbc]

Rough idle on cold and does bounce slightly on occasions once it's warmed up

[Ashbc]

Rough idle on cold and does bounce slightly on occasions once it's warmed up

[thekurgan]

Originally Posted by Ashbc

Rough idle on cold and does bounce slightly on occasions once it's warmed up

There have been issues with the fuel tank purge valve, some have had luck running a fuel system cleaner. If you have no codes thrown ... how many miles on the vehicle and have the spark plugs been changed?

[Ashbc]

60k miles, spark plugs haven't been changed as far as I'm aware, il get the service bits n change plugs and leads.. Let's see how it runs after that..

[buddalun]

Originally Posted by Ashbc

Rough idle on cold and does bounce slightly on occasions once it's warmed up

My car is exhibiting similar behavior on occasion. I had spark plugs and oil change (in addition to other maintenance items) completed by dealer yesterday. I'll report back if the slight bounce (on colder days especially) goes away after this work. My car has 29k miles and is an 11.75' E90.

[Flying Ace]

check battery connection

check idle air control valve

these two are the most common causes. Idle air control valve has been documented as a common problem.

[buddalun]

Battery connection is solid, just checked.

I just began researching the IACV issue; I was unaware of this before, thanks Ace.

http://www.m3post.com/forums/showthread.php?t=433138
http://www.m3post.com/forums/showthread.php?t=836709
http://www.m3post.com/forums/showthread.php?t=744557

Here is a DIY:
http://www.m3post.com/forums/showthread.php?t=842102

For posterity, I just discovered, the IACV is also called an Idle Control Device on our cars. It is covered by the factory California extended emissions warranty for 7yr or 70k miles. The CA extended emissions warranty also covers other jurisdictions, like Oregon, good for me. Check your factory warranty manual for details. For MY 11' E9X M3s the warranty applies to:

*The California Emissions Control System Limited Warranty applies to all 2011 U.S.- specification BMW vehicles registered in California, Connecticut, Maine, Maryland, Massachusetts, New Jersey, New Mexico, Oregon, Pennsylvania, Rhode Island, Vermont or Washington.

This is a costly repair. Benvo reported it cost nearly $4k in 12':
http://www.m3post.com/forums/showthread.php?t=744557

[Sandye90m3]

It also might be your O2 sensors. Just dynoed my car, and the car made no power after 7200rpm and a/f was very rich at 11.4.

I also have a very rough cold start, but it does sound cool haha.

Next two weeks, will include replacing, rod bearing, O2 sensors, engine mounts (if needed) and solid rear diff bushings

[Ashbc]

Changed all service parts plus plugs and leads, runs like a complete different animal now 😍😍😍