[Lihavajaruma]

Hey so recently got a 335xi 09. When my father(I’m military so I’m away for 3-4 weeks so he said he’ll pay/deal with most things but he’s stumped right now) starts it up it makes a rattle noise then it idles rough for 10 seconds or so. Mechanic replaced coil for cyl 4 twice. Then replaced spark plug for 4. Within driving it out of the mechanic the service engine light came back on & start up issues persisted. Wondering what it could be? The mechanic expected the light to come in and said it could be “water getting into the cylinder”.

[jiggz]

Can't help w/ your specific question, but you should try posting this on the E9x non-M3 pages of this site - our cars here have a totally different motor than the one in your car. Good luck sorting it out.

https://www.e90post.com/forums/index.php

[Lihavajaruma]

Originally Posted by jiggz

Can't help w/ your specific question, but you should try posting this on the E9x non-M3 pages of this site - our cars here have a totally different motor than the one in your car. Good luck sorting it out.

https://www.e90post.com/forums/index.php

appreiciate didn't realize I posted it in the wrong section

[Scrippy]

I had a 335 before my M. The most common rattle for the n54 motor would be the wastegates on the turbos but this would generally cause OVER or UNDER boost errors to be present. The only other rattle I could think of off hand would be vanos system due to oil pressure or improper vanos adjustment.

[amrazM]

Use ista and look for faults in the injectors.

[E46M3forRay]

HPFP have been a known issue on this car. Mine was replaced 3x by the dealer.

BMW has extended the warranty to 10yrs/120k miles
https://www.scribd.com/doc/153404704...Extension-TSB#

Find out what the codes are and reference it to the link above. If there’s a match, call your dealer or bmw NA and see if it’s covered.