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Discussion Starter #1
So I went on a 20 minute ride to get a haircut. After I was done (about 30-40 minutes later) I started the car and the idle was fluctuating from 700-1000 while stationary. I drove a few minutes and eventually it stopped doing it but why would it do that when the car was already warmed up?
 

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My car did the same thing. I *****ed/moaned/complained to the dealership and it fell on deaf ears. Got my oil changed a few weeks ago and low and behold the car does not idle crazy anymore.

The only downside to the dealership changing the oil is that now my car is a little quieter. They did not install the foam pad thingys in the air intake system.

My car was extremely loud at startup (stock exhaust/stock everything) and it was kind of cool. Now, the car is behaving itself and I'm worried.
 

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My car did the same thing. I *****ed/moaned/complained to the dealership and it fell on deaf ears. Got my oil changed a few weeks ago and low and behold the car does not idle crazy anymore.

The only downside to the dealership changing the oil is that now my car is a little quieter. They did not install the foam pad thingys in the air intake system.

My car was extremely loud at startup (stock exhaust/stock everything) and it was kind of cool. Now, the car is behaving itself and I'm worried.
I take that back. My car still fluctuates wildly at idle. Both cold and warm startups.
 

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Discussion Starter #4
What's bizarre is that after another 6 hrs of sitting, no fluctuation on the idle

I take that back. My car still fluctuates wildly at idle. Both cold and warm startups.
So, I came back at work at 12:30 and had the car parked for 6 hrs. Started it up and it idled perfectly. Obviously something is going on otherwise it would be more consistent than that. Either steady idle at every start or fluctuating idle at every stop. Why is it flip flopping?
 

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Mine the same, very occasional and normally when very hot and idling in traffic for long periods, made having a loud exhaust unbarable and embrassing!!

Jay
 

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mine too and stalls... I pulled out some spark plugs and it had oil on the threads and tip.... any idea?
 

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mine too and stalls... I pulled out some spark plugs and it had oil on the threads and tip.... any idea?

These motors are built kind of loose which is why they burn so much oil. Loose is fast but as a result the car will burn oil when you beat on it. Burnt oil is just oil slipping past the piston rings so I would think to see a little oil on the plug is not completely out of the ordinary. How much oil is supposed to be there, I am not sure.

My car idles like pretty bad when I first start it up, hunting up and down trying to find it's way. I've never had an issue after warmed up.

At 30K miles I believe the plugs are supposed to be changed, so if your car is coming up around that milage maybe it's time to change the plugs. (don't quote me on the exact mile for the plug change but I know it's around there).

Check your idrive, it will tell you when the plugs need to be changed.
 

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I am very affraid that this may be a failing fuel pump. It was very common on BMWs with the N54 engine. Here's a link to the class action lawsuit: Lemon Law Search Results for bmw 335
 

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Discussion Starter #10
Are you sure about that? The failing HPFP on the 335is literally put the car in limp mode. The rough idle I was talking about when I started the thread is just that, rough idle and it only happens after you run the car hot, turn it off for a while and start it back up. Doesn't sound like a fuel issue to me. It sounds more like an ECU programming issue.
 

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I'm not to sure, my father has a 2007 335xi but I don't think he has ever experienced somehting like this. The oil temps though... 270 degrees. I suggested that he get the Sports Package with the Oil Cooler but well, he din't. Just thought I'd mention it though. I've found video tapes go a long way with the mechanics at the dealers. If you experience it try to video tape it.
 

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I have the rough idle problem as well (somewhat)... I start the car up when the engine is cold and the idle fluctuates from 750-1000RPM for a 5-10 seconds but smooths out quickly. I was concerned at first but I don't seem to be having any problems with the car and this only happens on a cold start. I am a little nervous about winter though if the cold is what causes the fluctuation at start-up. We'll see how it goes. The car is still under warranty until next July, so I can always bring it to the dealer if something is wrong.
 

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. . . consider also that either a small vacuum leak or a dirty air idle control valve could cause idle fluctuations. If your car is out of warranty and/or if you like to tinker, you might try cleaning the ICV. There are instructions all over the internet for various car. One might be relatively applicable to our cars. Good luck finding a vacuum leak.
 

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Discussion Starter #14
The cold rough idle happens on all E60 M5s as far as I know

I have the rough idle problem as well (somewhat)... I start the car up when the engine is cold and the idle fluctuates from 750-1000RPM for a 5-10 seconds but smooths out quickly. I was concerned at first but I don't seem to be having any problems with the car and this only happens on a cold start. I am a little nervous about winter though if the cold is what causes the fluctuation at start-up. We'll see how it goes. The car is still under warranty until next July, so I can always bring it to the dealer if something is wrong.
The OP was about rough idle after the engine has been run hard, then turned off then turned on again.
 

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My car does this as well intermittently warm or cold -- generally notice it more right after starting the vehicle (even if it was just turned off). It actually bounces between 550 to 950 rpm before randomly stopping. The tech ran some tests at the dealer and thinks its the vanos pump in my case...
 

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Discussion Starter #18 (Edited)
FYI: In really cold weather, the rough idle will last longer than 5-10 seconds

I have the rough idle problem as well (somewhat)... I start the car up when the engine is cold and the idle fluctuates from 750-1000RPM for a 5-10 seconds but smooths out quickly. I was concerned at first but I don't seem to be having any problems with the car and this only happens on a cold start. I am a little nervous about winter though if the cold is what causes the fluctuation at start-up. We'll see how it goes. The car is still under warranty until next July, so I can always bring it to the dealer if something is wrong.
Possibly up to 30-45 seconds.
 

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My Dad paid a visit today and as we went out to get something at the store the car sat for about 50 minutes. When we went to go start it up, it noticed a similair problem to the one decribed in your post, odd.
 
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