Christopher Allen

Ok so I have a 2009 e60 528i xdrive with 200k miles and the car drives great unless you realy get on the gas hard. When you press on the gas to pass or get on the hyw it will studder and run like shit then the check engine light will come on and the car will run that way untill you pull over and shut it off the when you start it back up the check engine light goes away untill you try to get on it again. As long as you baby it there's no issues I've ran an obd2 scan and its giving me a random misfire code... any help would be appreciated thanks

seanjordan20

Do a smoke test. Sound like a vacuum leak

audiophool

When was the last time the spark plugs were changed? Look at those, then the coils.

seanjordan20

That would be a good thing to check but doesn't a random misfire mean all cylinders are misfiring randomly. If it was a coil or plug it would through a code for the specific cylinders that are being effected.

audiophool

Key here is WOT failure. Sparkies are under the most stress at WOT and high RPMs. The DME doesn't like recovering from these misfires by itself, hence running OK after re-start.

seanjordan20

Yes but still l a random misfire has a different code in itself.

audiophool

I had 'random misfire' codes as well as misfire codes on #5 and #6 when I had a leaking injector on #6. Replacing the one injector fixed it. I suspect 'random misfire' is a lower level code rather than a firm failure.

seanjordan20

That makes sense. If you have a random misfire coupled with cylinder misfires you would check plugs, coils and injectors on the bad cylinders but if you only have a random misfire you start at vacuum or intake.

Christopher Allen

Its definitely coupled with multiple cylinder misfire

seanjordan20

Ok now with all the information I would check the bad cylinders. First by swapping the coils to see if the codes move around. Only you know how old your plugs are so that should have been thought of if the car is only a scheduled maintenance plan. After checking coils start looking at vacuum hoses and intake (personally I would do a smoke test it goes faster and finds leaks where it's hard for the eye to see). How many bad cylinders did you have? How old is your battery? Do you drive it regularly?