my check engine light was on and when I had the checked it said it was the egr valve. I changed that still missfire. I took it to another mechanic and he says the vacuum line the goes to the egr valve to the engine could be clauged up, he apparently has been working on C36 when they first came out and they have a problem like this.

As for codes, if i recall it said p0400, if that makes sense, give or take a zero at the end.

Sorry for my lack of knowledge but this car is driving me nuts already.

I have rebuilt the engine from ground up, and all these problems started to occur when I disconnected the ecu with out first disconnecting the battery.