N52 Idle drop followed by surge to normal

e91Owner · 10-11-2020, 11:40 AM

New this summer has been an issue with my 2011 e91 at idle. 68k miles. Sitting at a stop whether in gear or not at 650 rpm, the engine will quickly drop to 550 and then surge back to normal. The surge is pretty pronounced and shakes the car. All in about a second. No codes at all. I'm planning on cleaning the vanos solenoids tomorrow—anyone else that has had this same problem and subsequently fixed it? My N52 e60 hasn't had this issue in 110k.

e91Owner · 10-12-2020, 06:16 PM

Well, I cleaned the vanos solenoids which were clean already. They energized just fine and the problem is still there. I'll probably clean the non-return valves tomorrow, but my guess is they will also look good. Anyone have another guess? I'm just flying in the blind here without it pulling any codes.

10-11-2020, 11:40 AM	#1
e91Owner e91Owner 441 Rep 1,149 Posts Drives: 2011 e91 Join Date: Mar 2018 Location: Out of the Office iTrader: (0)	New this summer has been an issue with my 2011 e91 at idle. 68k miles. Sitting at a stop whether in gear or not at 650 rpm, the engine will quickly drop to 550 and then surge back to normal. The surge is pretty pronounced and shakes the car. All in about a second. No codes at all. I'm planning on cleaning the vanos solenoids tomorrow—anyone else that has had this same problem and subsequently fixed it? My N52 e60 hasn't had this issue in 110k.
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10-12-2020, 06:16 PM	#2
e91Owner e91Owner 441 Rep 1,149 Posts Drives: 2011 e91 Join Date: Mar 2018 Location: Out of the Office iTrader: (0)	Well, I cleaned the vanos solenoids which were clean already. They energized just fine and the problem is still there. I'll probably clean the non-return valves tomorrow, but my guess is they will also look good. Anyone have another guess? I'm just flying in the blind here without it pulling any codes.
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