Unfixable Rough Idle N52

nicholas6706 · 11-12-2024, 05:19 PM

I'm attempting to fix a persistent n52 idle vibration. When the rpm's drop after stopping, it will hang at ~800rpm for a few seconds before coming back down to 600. I've smoke-tested the intake and there are no vacuum leaks. There are no engine codes. I've replaced the following (all OE spec):

Entire engine (spun crankhub)
Eccentric shaft sensor
Valvetronic motor
Throttle Body
6x sparkplugs + coils
All gaskets (Oil pan, VCG, OFHG, TB, intake manifold)
2x vanos solenoids
PCV system
Engine mounts
2x o2 sensors
6x injectors
Crankshaft pos sensor
Camshaft pos sensor

Any help would be appreciated.

rothwem · 11-15-2024, 01:37 PM

Quote:

Originally Posted by nicholas6706

I'm attempting to fix a persistent n52 idle vibration. When the rpm's drop after stopping, it will hang at ~800rpm for a few seconds before coming back down to 600. I've smoke-tested the intake and there are no vacuum leaks. There are no engine codes. I've replaced the following (all OE spec):

Entire engine (spun crankhub)
Eccentric shaft sensor
Valvetronic motor
Throttle Body
6x sparkplugs + coils
All gaskets (Oil pan, VCG, OFHG, TB, intake manifold)
2x vanos solenoids
PCV system
Engine mounts
2x o2 sensors
6x injectors
Crankshaft pos sensor
Camshaft pos sensor

Any help would be appreciated.

Shit man, you've basically done the whole car. Could it be in the transmission? Any difference between neutral and drive?

nicholas6706 · Yesterday, 11:30 PM

Quote:

Originally Posted by rothwem

Shit man, you've basically done the whole car. Could it be in the transmission? Any difference between neutral and drive?

Yeah it's pretty frustrating. Unfortunately no difference in any of the gears.

sabino56 · Today, 09:51 AM

Perhaps remove the serpentine belt and see if vibration changes/is gone. Hard to compare idle vibrations but I had a slight, weird vibration at idle which I tracked to the overrunning clutch on the alternator. It had frozen solid. If you have the belt off you can check the alt pulley by preventing the alternator from rotating with screw driver (carefully) and the pulley should turn freely one way and be locked to the alt shaft the other.
This is thread on my problem, maybe you can tell if yours is similar or different. https://www.e90post.com/forums/showthread.php?t=1962637

11-12-2024, 05:19 PM	#1
nicholas6706 New Member 5 Rep 20 Posts Drives: 2006 330i Join Date: Aug 2020 Location: United States iTrader: (0)	Unfixable Rough Idle N52 I'm attempting to fix a persistent n52 idle vibration. When the rpm's drop after stopping, it will hang at ~800rpm for a few seconds before coming back down to 600. I've smoke-tested the intake and there are no vacuum leaks. There are no engine codes. I've replaced the following (all OE spec): Entire engine (spun crankhub) Eccentric shaft sensor Valvetronic motor Throttle Body 6x sparkplugs + coils All gaskets (Oil pan, VCG, OFHG, TB, intake manifold) 2x vanos solenoids PCV system Engine mounts 2x o2 sensors 6x injectors Crankshaft pos sensor Camshaft pos sensor Any help would be appreciated.
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Today, 09:51 AM	#4
sabino56 Private First Class 89 Rep 152 Posts Drives: 2006 E90 330i Join Date: Mar 2018 Location: AZ, Tucson iTrader: (0)	Perhaps remove the serpentine belt and see if vibration changes/is gone. Hard to compare idle vibrations but I had a slight, weird vibration at idle which I tracked to the overrunning clutch on the alternator. It had frozen solid. If you have the belt off you can check the alt pulley by preventing the alternator from rotating with screw driver (carefully) and the pulley should turn freely one way and be locked to the alt shaft the other. This is thread on my problem, maybe you can tell if yours is similar or different. https://www.e90post.com/forums/showthread.php?t=1962637
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