So I went to go get some lunch with a friend and when we got back to the car it would start and die out immediately. Ive already replaced one coil pack but the other is original. I got the car to start and it went into what i figured was "limp mode". i drove home like this and when i got home and into the garage i turned it off and restarted. Upon restarting there was no issue and limp mode along with the rough idle was gone. The check engine light is on and im assuming its cylinder misfire since it has thrown codes for this twice before but never gone into limp mode before.

So the question is, does this mean my other coil pack is going out or just a hiccup? I should just replace the other coil pack i know. Thing is ive owned more than 11 bmw and mercedes cars before and all of them have had electrical gremlins once or twice and then they disappear.

Thoughts?

could also be an ignition voltage transformer. hard to diagnose, similar symptoms to a bad coil pack, but sometimes intermittent.

My car has almost the exact same fault. Occasionally, on hot restart, it will stumble and die or run poorly. Me giving it some gas for a minute and shutting it off and restarting will usually clear it. Codes come up for scattered misfires (both banks). I recently did all 24 spark plugs, and ended up breaking one coil so I replaced that side. Changed nothing. I know it's heat soak related, so it's either the ICM (transformer) which I may change soon anyway as they are cheap (relatively) and the new ones are an upgraded part, or it's a fuel boiling issue, need to test that theory though. I can duplicate the issue by driving the car hard and getting it good and hot, and parking for more than 10-15min. It will always be hard to re-start. If it sits for an hour it's usually ok.

I just read that earlier today. This is intermittent. I also found a place that rebuilds

This is exactly what happens with me but it had never ran poorly. It's actually only 40 degrees here in Chicago so not too hot though the motor was nice and hot.

The good thing is it went away and so did my check engine light. I might send out the transformer to get rebuilt and start from there. I don't drive this car in the winter or even often if that. Was just very nice out and decided to take it for a cruise.

you can get a new one on line for a little more than the rebuild i believe.

oh excellent biker thanks for the info