Cold Temp Start - Rough idle and check engine light

[madr1]

Cold Temp Start - Rough idle and check engine light. This has been happeneing for a while now... I was also getting the engine malfunction derate, but I had it at the dealer, and they changed the HP pump without diagnosis because their computer was down (had the car 4 days becasue of their programming computer down) and had to reprogram after the pump install. (no problem, they gave me an X3 that was new). They also replaced an air tube to the turbo due to a pin hole leak.

With their computer down, I think they missed a misfire problem - service engine light comes on, and was even blinking the other day, but only after a cold temp start, after work. Usually clears up after a restart, which is odd.

The dealer is an hour or so away, and when I got home, the engine was ticking loudly after the hour drive at idle. 2 days later, after a full day at school, and below freezing temps, check engine light again. Since I park in a heated garage - no problem in the morning, but after being outside in below freezing temps, it is very repeatable.

Is anyone else seeing this specifically on cold temp starts?

I also noticed it was running rougher on the highway this weekend - almost like a rotaional imbalance (misfire), and I swear there was backfire while decelerating on the hwy.

I have been waiting a few weeks to get back in the dealer, but I am thinking of having it towed here pretty soon.

[nmonfared]

I experienced the exact same thing and it was the high pressure fuel pump. They replaced mine and it seems to be driving fine.

Take it back to the dealer and tell them that it's still messed up, you could have a serious problem with the engine if they replaced the fuel pump already. Last thing you need is breaking down in the side of the road. If it's really an hour away I'd stay on the safe side and have BMW assist tow it.