Start Up Misfire

[MickeyB]

Looking for some help. I have a 2003 Z4 2.5 sport recently acquired and love it. The only problem is that I cannot get rid of a service engine light that continues to refer to a misfire in cylinder #2. Have replaced coil, changed spark plugs and had engine cleaning additive applied that is still being worked through system. Seems to be an issue at start up but then settles into a smooth ride. I've been told to run the engine and blow out the engine and that will clean the lifter that is still sticking. Is that all it is or should I consider something else???

Z Love

[andyfanshawe]

Hi.
What's the history on this car? Is it not used very often? What's the mileage on it?
Not sure how much equipment you have, but I would run a compression check on all cylinders to rule out major piston ring/bore wear.
Pretty quick to do.
I would scope the ignition primary on this and the injector pulse to get a direction.
Suppose another way for the diy'er is to swap the injector from cyl 2 to cyl 3 to see if the misfire moves.
Hope this helps a bit.
Andy.

[MickeyB]

Thank you Andy. The car has 78k miles, clean and regular maintenance record. I drive it on weekends and not too much. Misfire coded on #2 cylinder and diagnosed as coil pack problem. Replaced coil pack and swapped it when light came on again. No move on the misfire. Flushed injector system next w full plug replacement a bit earlier than planned. Better performance but misfire came back. Ran compression test next. 180 on #2 w/ 190 and 200 on the others. Was told that was within acceptable limits. Swapped coil pack and plug next along w an engine flush. Still working though the flush treatment w high RPM riding. Fingers crossed but uncertain. I'm told that the lifter is sticking but not keen on replacing. It's a frustrating cycle. Appreciate any and all suggestions.

MickeyB

[andyfanshawe]

Hi mickey. Did you solve this?

Andy

[MickeyB]

Hi Andy, Thanks for asking and yes I did. First switched mechanics to ones more familiar with the car. They confirm the issue particularly with misfire at cold start and that it was isolated on #2 cylinder. Scoped and smoke tested for any other leakage with no effect. One of the seasoned mechanics suggested we check the lifters, and found an ever so slight movement on #2. Replaced all four and it runs like a top now. A long journey but a great outcome. Thanks so much for the input helping to keep me on the right track

Best Regards,
Mickey

[ph001]

Thanks for the update OP. I wonder why this only exhibited a problem at start up and then settled into a smooth ride when warmed through? Glad you got it sorted