[will.c]

Keeping it short..

Nov 06 built 335i
now @81k miles
intake ports cleaned @60k
new plugs, oil filter housing gasket, turbos, waste gates, injectors, coolant flush @78k

No problem @ 3000rpm-redline, very smooth while revving high regardless of how much throttle input.

while idle (around 550-600rpm) it's mildly rough. I can feel the car intermittently shake as the result of engine misfiring I think. Sometimes it even dips below 500rpm, then it realizes that and bumps up the idle rev to 700-ish, at which rpm it's still mildly rough.

Should I replace all 6 coils? Should I try resetting the ECU? Or both? Which one should I try first?

THANKS!

[JamesM3M5]

Mine does the same with new plugs. It was better, but still does the exact same thing you describe. I have not changed injectors, but Shiv at Vishnu reported that fixed his problems and gained power, too. You say yours have been changed, but you may want to read the numbers off them and make sure the ECU was coded with the proper numbers. Each injector comes with calibration numbers from the factory, and that must be entered whenever injectors are changed. Additionally, some have reported that either the injector seals and/or decouplers were bad, and one found that whomever changed his injectors (dealer tech) didn't even put decouplers on them before installing.