Quote:
Originally Posted by bawareca
Most problems with the M54 and N52 engines with a single cylinder misfire come from the ignition coils. As a matter of fact, in DIS and ISTA test schedules, if there is a misfire always the same instruction pops: "If the engine is equipped with Bremi igntion coils replace all of them"  |
Sorry, HAVE to totally DISAGREE at least with the M54 problems being ignition coils. Yes they can be an issue from time to time, BUT most idle misfire problems are due to LEAN conditions.
The E70 is a bit young and may be a different configuration than the earlier M54 equipped cars to have the rampant vacuum and crankcase air leaks. An OBDII tool to monitor the warm idle Fuel Trim values is a good start for identifying vacuum and crankcase air leaks.
Many of the cold start misfires are also vacuum leaks from heat compressed silicon or rubber gaskets that do not expand like they should when cold.
Lean misfires due to vacuum leaks are not just on BMW's, EVERY manufacturer has this problem starting around year 8. Plastic and rubber that holds vacuum under the hood of a modern vehicle does not survive beyond 8 years on average.