knowing the codes is essential... did your original story with bang sound like a backfire on the old cars?

we just helped a fellow (diddy0071) troubleshoot something similar... you go in order from simplest to the most complicated.

you replaced the spark plugs and the coils - what brand of each did you use? was it is BMW original, or BOSCH (or other OEM)? or, was it some off-brand made on some unknown island in Asia?

since you are venturing into the engine diagnostics, i would strongly suggest buying diagnostic software INPA, GT1 along with the OBD to USB cable - in your case you also might need to buy the 20-pin round cable adapter for the data port in the engine bay. with diagnostic software at hand, you can read the codes, reset them, watch the new codes being set in the system, you can watch the live engine performance...

with that info at hand, you can throw more information on this forum, and i am sure, there will be somebody who can pinpoint the problem for you...

doing the diagnostic without the sotfware is like flying blind - you need to be helluva good mechanic to know what is happening there... or, keep throwing parts at the problem... which, after the fuel filter, next one will be fuel pump...

did you read this thread - http://www.xoutpost.com/bmw-sav-foru...essing-up.html?