Fluctuating idle during cold cycle

[Dougeefresh]

Happens when cold starting and last anywhere from 10 - 30 seconds at the end of the cold cycle then settles down. Car shakes more than usual when this happens and you can also hear it. Started a couple months ago.

Do I need to take it to the dealer?

Here is the video of the last 10 seconds I caught. You may need to listen with a headphone.

[Stallion150]

Wow, same exact thing my car is doing. Its in the shop now: same noises and tachy needle bob. They changed idle control valve, coolant temperature sensor, idle air fluctuator and no fix.
.
A friend told me that maybe the DME (Digital Motor Electronics) needs to have a software update. Mine is a 2011 E90.
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Will post when I get my car back.

Check out my video:

[MikeD]

Idle air control valve issue. Very common in our cars.

Get it fixed asap or at worst your car won't hold idle and will be nearly impossible to drive safely. Ignition would cut out while you're stopped at a light, etc. Happened to me before when I let this problem persist. Almost couldn't drive it in traffic bc engine kept cutting out without my foot on the gas.

Should be covered under warranty or 7-years emissions warranty

[Stallion150]

Originally Posted by MikeD

Idle air control valve issue. Very common in our cars. Get it fixed or at worst your car won't hold idle and will be nearly impossible to drive safely.

Should be covered under warranty or 7-years emissions warranty

From my experience it's not that simple; the dealer replaced all of the above and the problem still hasn't gone away.

[MikeD]

Originally Posted by Stallion150

From my experience it's not that simple; the dealer replaced all of the above and the problem still hasn't gone away.

Yep, for you, you've got more complex issues related to DME...

I'm just saying at a minimum all the idle related hardware needs to be replaced first. OP implied he's never taken his car in before.

[Stallion150]

Yeah wish it wasn't complicated, you would think it would be a simple fix!

[nickdrivesm3]

Ask them to clear the DME engine adaptations. I've had to replace a DME before for a reoccurring idle valve fault.

[Dougeefresh]

Originally Posted by Stallion150

Wow, same exact thing my car is doing. Its in the shop now: same noises and tachy needle bob. They changed idle control valve, coolant temperature sensor, idle air fluctuator and no fix.

Does your problem only happen when cold starting?

[Stallion150]

Originally Posted by nickdrivesm3

Ask them to clear the DME engine adaptations. I've had to replace a DME before for a reoccurring idle valve fault.

Thanks man! Will definitely let the techs know.

OP, this happens only on the 2nd start of the day usually. On a cold start in the am, it idles fine. Usually I'll come back about 8 hours later from work, and I'll notice it when it starts up. If they fix it, I'll definitely let you know what it was.

[Stallion150]

I just got the car back. They couldn't replicate the fault, but replaced the differential pressure sensor for intake. Does that make any sense?
Apparently checked DME and it was functioning normally.

[Dougeefresh]

Had the car in for brake fluid flush and oil change so I mentioned the idle fluctuation.
They replaced idle control valve and the car seems to idle fine (first day back).
Will report back if anything changes.

[anom3]

so, i had the same issue. when i say same issue, IDENTICAL. first 0-30 secs idle would bounce like a basket ball.

i changed 2 things, and the issue was fixed right away:

a) this is a known issue with shell vpower 100 gas. if thats what you filled up with, switch to another brand for 1-2 tanks. chances are if you filled up with shell, this will go away.

b) i installed rpmsport tune, in the process my ecu was upgraded from 50E to 240E.

i did both of the above at the same time, and my idle is super stable now. cold start or not. its at 800rpm solid.

[anom3]

i have also read this happens frequently when people change their spark plugs.

you may ask your dealer to reset your adaptations. regardless weather you changed your plugs or not.

[rocket_science]

Can it really be all of the above??? From years of being a shadetree mechanic working on engines, there is almost always a common denominator. Seems the culprit is still up for debate though...

[Dougeefresh]

No Shell or spark plug change for me.
I may have spoken too soon. I felt a bit of the bouncing act coming back, shorter time frame, however. WILL see if it gets worse.

[happos2]

Can't see the video where I am at...but potentially a vaccuum issue?

[Stallion150]

Originally Posted by anom3

so, i had the same issue. when i say same issue, IDENTICAL. first 0-30 secs idle would bounce like a basket ball.

i changed 2 things, and the issue was fixed right away:

a) this is a known issue with shell vpower 100 gas. if thats what you filled up with, switch to another brand for 1-2 tanks. chances are if you filled up with shell, this will go away.

b) i installed rpmsport tune, in the process my ecu was upgraded from 50E to 240E.

i did both of the above at the same time, and my idle is super stable now. cold start or not. its at 800rpm solid.

That's interesting--I get my gas from shell exclusively. I'll try switching it up. I got the car back; They checked it through and through and called the regional BMW lead tech. No further faults gleaned.

[kablammo]

Check your m3 supplement manual. States it will rough when cold due to emissions systems.

[s85e90]

Totally normal and sometimes more than others. Started my car the other day after sitting for 2 days and the car was like being awakened from the dead and actually didn't run well until warmed up and on the freeway. The personality of the motors.

[Bel-Tirid]

i have this idle poping more then 4 years now

[Stallion150]

OP, any resolution on this problem? I'm still having it on every other cold start. It's driving me nuts. Off to the dealer again...

[GTB/ZR-1]

I just tell people my car has a 'cam' in it... lol
Seriously, my car is an '11 with all of 4700 mi on it & doing this already.