N52 Help: Vibration at idle :(

sabino56 · 10-01-2023, 11:10 AM

You would only want to let it run a minute, just long enough to see if the same rough idle remains. It will set a check engine light also, if my memory is correct from when I did it. It may also idle at slight different rpm? Can’t remember.

I have no clue if an accessory is really the problem - but it’s a way to decide yes or no. If you do it, I’d warm up engine and get it to point where it’s repeatedly having the rough idle on restart. Then take off belt and see if same roughness or not.

When I was chasing my problem the car ran noticeably smoother with belt off. Then I measured and got a couple shorter belts from autozone to delete the a/c and then the pwr steering pump from loop while still turning alternator so I could run it longer. The rough idle only went away when the alternator was not turning which is how I zeroed in on the overrunning pulley which solved my version of “rough” idle.

As I mentioned, “rough” idle is a wide range and many, many things can cause various levels of idle problems. Looking thru this forum you’ll see people digging into all sorts of systems trying to chase down problems. I just suggested this as it’s easy, something to potentially check. Good luck!

justinkoreska · 10-04-2023, 08:17 PM

As recent E91 owner and lurker of this forum since, I want to contribute my recent experience with "rough idle" so I'm replying here for rep.

In my case, I have just replaced the Valve Cover Gasket (VCG) plus Valvetronic motor and eccentric shaft sensor seals. After, when idle dropped to 600 RPM it got choppy (or rough).

Of course I checked my work for leaks and seated coils and plugs but then suspected the crankcase ventilation or breather hose (as I understand is a delicate part) and replaced it. The hose itself seemed fine (but brittle) so I think the connector o-ring to the valve cover had failed.

Just my 2 bits in case it helps the next FNG.

coriolis14 · 10-30-2023, 04:13 AM

Final update here: my vibration at idle got so bad today while driving around I went and checked to see if any codes got recorded. Sure enough I got a cylinder #2 misfire and replaced the coilpack last evening. Took the car on a test drive and the vibration is gone (for now).

I also noticed an oil leak coming from around the Valvetronic motor (between cylinders #3/4) that I need to observe/take care of.

I guess the shocking / surprising thing for me was the fact that a faulty coilpack expressed itself at idle. I assumed (wrongly) that a bad coilpack would also cause issues while the car was in motion/the engine was producing more power, but that was not the case at all.

crashoverride · 11-21-2023, 05:47 PM

If you replaced one coil you need to replace them all. Not too weird to have the misfire at idle. The alternator isn't moving too quick so the power being supplied is minimal.

For example my alternator was on the fritz a bit ago. I was driving to mechanic and the red electrical symbol came on when I pulled up to a light. I revved the engine up and it would make red light go away.

10-01-2023, 11:10 AM	#23
sabino56 Private First Class 103 Rep 161 Posts Drives: 2006 E90 330i Join Date: Mar 2018 Location: AZ, Tucson iTrader: (0)	You would only want to let it run a minute, just long enough to see if the same rough idle remains. It will set a check engine light also, if my memory is correct from when I did it. It may also idle at slight different rpm? Can’t remember. I have no clue if an accessory is really the problem - but it’s a way to decide yes or no. If you do it, I’d warm up engine and get it to point where it’s repeatedly having the rough idle on restart. Then take off belt and see if same roughness or not. When I was chasing my problem the car ran noticeably smoother with belt off. Then I measured and got a couple shorter belts from autozone to delete the a/c and then the pwr steering pump from loop while still turning alternator so I could run it longer. The rough idle only went away when the alternator was not turning which is how I zeroed in on the overrunning pulley which solved my version of “rough” idle. As I mentioned, “rough” idle is a wide range and many, many things can cause various levels of idle problems. Looking thru this forum you’ll see people digging into all sorts of systems trying to chase down problems. I just suggested this as it’s easy, something to potentially check. Good luck!
	Appreciate 0 Quote

10-04-2023, 08:17 PM	#24
justinkoreska Registered 0 Rep 1 Posts Drives: BMW E91 Join Date: Oct 2023 Location: Toronto, Canada iTrader: (0)	As recent E91 owner and lurker of this forum since, I want to contribute my recent experience with "rough idle" so I'm replying here for rep. In my case, I have just replaced the Valve Cover Gasket (VCG) plus Valvetronic motor and eccentric shaft sensor seals. After, when idle dropped to 600 RPM it got choppy (or rough). Of course I checked my work for leaks and seated coils and plugs but then suspected the crankcase ventilation or breather hose (as I understand is a delicate part) and replaced it. The hose itself seemed fine (but brittle) so I think the connector o-ring to the valve cover had failed. Just my 2 bits in case it helps the next FNG.
	Appreciate 0 Quote

10-30-2023, 04:13 AM	#25
coriolis14 Private 14 Rep 53 Posts Drives: 2007 E92 328i Join Date: Jan 2014 Location: Los Angeles, CA iTrader: (0)	Final update here: my vibration at idle got so bad today while driving around I went and checked to see if any codes got recorded. Sure enough I got a cylinder #2 misfire and replaced the coilpack last evening. Took the car on a test drive and the vibration is gone (for now). I also noticed an oil leak coming from around the Valvetronic motor (between cylinders #3/4) that I need to observe/take care of. I guess the shocking / surprising thing for me was the fact that a faulty coilpack expressed itself at idle. I assumed (wrongly) that a bad coilpack would also cause issues while the car was in motion/the engine was producing more power, but that was not the case at all.
	Appreciate 1 sabino56103.00 Quote

11-21-2023, 05:47 PM	#26
crashoverride Lieutenant 191 Rep 585 Posts Drives: na Join Date: Jul 2006 Location: na iTrader: (0)	If you replaced one coil you need to replace them all. Not too weird to have the misfire at idle. The alternator isn't moving too quick so the power being supplied is minimal. For example my alternator was on the fritz a bit ago. I was driving to mechanic and the red electrical symbol came on when I pulled up to a light. I revved the engine up and it would make red light go away.
	Appreciate 0 Quote