i had the same problem on a brand new '09 s (3 days old)

temps got cold, but it's southern california so it's a relative term i think it hit the low 30's. it's at the service center now.

 

Our 2009 mini s is in the dealer again for the 3rd time for the engine light on, cold start rpm issues and won't move until you restart a few times and engine light is on. I talked to Mini service manager and he said they are aware of the problem and that his counterpart in Minnesota has had so many of these cars come in with this but he has only seen a few. He told me he was going to talk to the mini rep or something like that today and see if the fix is ready. He thought it may be but not released yet. Very frustrating in a new car. I will post when we hear back from the dealer.

 

Not sure if this is related, but I'll post it. I just had the thermostat fixed in my 07 MCSa. When it got cold enough, the computer detected the problem and threw up a CEL. During this time I had a very noticeable surge, sometimes at idle, but about 80-90% of the time when coming to stops for red lights and stop signs. Sometimes it was strong enough to want to jerk your foot off the brake. Also, the car would sputter quite often in reverse and if cold enough out would stall.

As time went on, on highway driving on several occasions the car would struggle to get past 60 or go into passing gear if you will. The computer was preventing it.

Turns out the thermostat was stuck open. Since being fixed, it's like night and day. I noticed that there is sometimes still a slight surge when coming to a stop, but it doesn't happen nearly as often or as strong. Though the guys at the dealer said a slight surge is normal for an S. But it no longer surges on idle and reverse is smooth as butter now. Also no problem getting up to highway speeds, that good ol turbo kick is back.

Oddly enough, when the temp was warm enough, like say about above 40 or so, the computer would not detect the problem and not throw up a CEL. I'm hoping it's fixed for good now, and with this absolutely horrible winter we're having in the northeast, it's really going to be tested.

 

got the '09 back today and so far no problems at all. they replaced the fuel pump. will keep you posted if the problem comes back.

 

Our 09 is still at the dealer and they said they were waiting to hear from their tech support in New Jersey since Thursday to tell them what to do with the faulty codes the car threw on the computer. I think they don't know how to fix it and are stalling for time. So we will not have the car until early next week. Keep you posted.