Cold Start Idle Stumble

[alpinecoupe]

During the cold start cycle; the first 10-20 seconds after the ignition button is pressed, the rpms are dropping lower than before.
On a few occasions there was a slight stumble, one time in particular the engine felt as though it was going to die..
(The car is routinely garaged, driven daily, and on this occasion the dash temperature read 72F).

This phenomenon did not occur until the engine had approximately 20K miles.
Before that the start up was smooth, going through the various rpm cycles until it settles in to a stable speed after ~20-30 seconds.

I mentioned this to the dealer and the reply was that these engines do not get hot enough during routine use.
Yes, but it did not happen when the car was new, nor did it occur on days when the ambient temperature was down in the 30s...

Given all that can, and unfortunately does, happen this is minor unless it progresses.
When I drove a vintage 914-6 with triple Webers, I expected some cold start "personality" but having this with the M3 seems out of character.

Anyone else experience this or have feedback from the dealer?

TIA

[Krozi]

Idle control valve?

[JCtx]

Yep, your idle control valve is going out buddy. You're going to be greeted by the 'christmas lights' pretty soon, I'm afraid . When you do, you can usually get rid of them a couple of times by restarting the engine, but will be permanent after that. Apparently for us '08 owners is not a matter of IF we're going to have a problem with the stupid idle valve, but WHEN. Just hope mine acts up within warranty, which I'm starting to doubt as I only put about 4K miles a year at best. Good luck man.

[alpinecoupe]

Originally Posted by elp_jc

Apparently for us '08 owners is not a matter of IF we're going to have a problem with the stupid idle valve, but WHEN.

This would indicate that there is a known problem...
which only adds to my dealer frustration as they blew it off as temperature related despite a detailed description.

In a perfect world I'd think they would at least note the issue and advise me to bring the car in when it fails or when impending failure is displayed via the "Christmas lights."

Might be time to look into the other dealer in town.

Thanks for the feedback.

AC

[alpinecoupe]

Additional clarification:

This low rpm / stumble only occurs during start up.

When the ignition is pressed the rpms go up,

then down, *

then back up,

finally settling down to normal idle speed after ~20-30 seconds.

The rpm drop only occurs at the 1st start up cycle drop.
After that the idle rpm remains stable.

Given that, do you still suspect the idle valve?

[Ant Man]

Originally Posted by alpinecoupe

Additional clarification:

This low rpm / stumble only occurs during start up.

When the ignition is pressed the rpms go up,

then down, *

then back up,

finally settling down to normal idle speed after ~20-30 seconds.

The rpm drop only occurs at the 1st start up cycle drop.
After that the idle rpm remains stable.

Given that, do you still suspect the idle valve?

I had exactly the same issue, ie fluctuating idle at cold start-up. Additionally the engine would 'hunt' at low revs. My problem was a faulty vanos (there are 4 vanos units in all). My dealer also changed the fuel vent valve as a precaution as this part was subsequently modified by BMW.

After picking the car back up, the issue was fixed but now the engine makes a deep low frequency knocking / thumping noise that is linked to engine speed and not dependent on accessory loads. It's going back again to the dealer.

[brava09]

Originally Posted by alpinecoupe

Additional clarification:

This low rpm / stumble only occurs during start up.

When the ignition is pressed the rpms go up,

then down, *

then back up,

finally settling down to normal idle speed after ~20-30 seconds.

The rpm drop only occurs at the 1st start up cycle drop.
After that the idle rpm remains stable.

Given that, do you still suspect the idle valve?

My M3 started to do exactly the same, and only after the car hasn't been used for a while.

I hope it's not an expensive fix, as my car is out of warranty.

Let me know what was wrong with your car in case you find out.

[NYCM3ryder]

yea man my m3 did the same thing and i just got the car. its an 2011 e90 with 2000 miles on it lol...

[mdosu]

idle air control valve is clogged up with junk already or just a faulty valve?
usually this doesn't get clogged for a good 90k miles.