E90 325i LCI rough idle

[pwatts]

Hi guys, literally 20km after passing 100,000km my 2010 325i began showing idle roughness, but after going through all the Youtube videos I couldn't hear something resembling mine. Audio recording below.

https://www.dropbox.com/s/5ftlft98kxj6nj0/n53_325i_idle_noise.mp3?dl=0

As can be heard it's like a low-pitch periodic rumble around once a second.

- No other symptoms/warning lights, performance is fine and noise disappears at higher revs
- It's smooth when cold starting and only begins after about a minute, and will persist when hot (most other similar issues appear to be worse when cold)
- Car is 100% stock and haven't had any recent service or work done.

Anything pointing towards something more specific than the usual plethora of potential causes, and anyone in specific to recommend in the CT (preferably close to Century City) area for diagnosis?

 

[husaindindar]

Hi guys, literally 20km after passing 100,000km my 2010 325i began showing idle roughness, but after going through all the Youtube videos I couldn't hear something resembling mine. Audio recording below.

https://www.dropbox.com/s/5ftlft98kxj6nj0/n53_325i_idle_noise.mp3?dl=0

As can be heard it's like a low-pitch periodic rumble around once a second.

- No other symptoms/warning lights, performance is fine and noise disappears at higher revs
- It's smooth when cold starting and only begins after about a minute, and will persist when hot (most other similar issues appear to be worse when cold)
- Car is 100% stock and haven't had any recent service or work done.

Anything pointing towards something more specific than the usual plethora of potential causes, and anyone in specific to recommend in the CT (preferably close to Century City) area for diagnosis?

Hi. Really hard picking up defects from that sound clip. However I do hear like an air vaccum sound that quite audible. Possible that the oil seperator (PCV) is blocked or one of those vent pipes could have a leak. You could open you oil cap while the engine is running and feel for a vaccum (Dont burn yourself). If there is a large vaccum, then I guess there's an issue with the vent system (PCV/hoses).
BTW> Messed up PCV's do cause rough idling...

Also check ECU for faults. These German cars store faults without showing engine light.


do let us know what you find

 

[pwatts]

Hi. Really hard picking up defects from that sound clip. However I do hear like an air vaccum sound that quite audible. Possible that the oil seperator (PCV) is blocked or one of those vent pipes could have a leak. You could open you oil cap while the engine is running and feel for a vaccum (Dont burn yourself). If there is a large vaccum, then I guess there's an issue with the vent system (PCV/hoses).
BTW> Messed up PCV's do cause rough idling...

Also check ECU for faults. These German cars store faults without showing engine light.


do let us know what you find

OK, I started the car, took off the cap and put my hand over the inlet: definite vacuum that got stronger for the 10s or so that I felt it. Also, when I removed my hand to put the cap back (while the engine ran), the offending noise let loose 10x more than before. With the cap back on it went away, and then gradually returned again to its normal level. So I guess this is likely the problem - question is, where in CT is a recommended place to have it fixed?

 

[Bmwed]

Had the same problem after my valve stem seals was replaced. Check the inside of your eccentric shaft sensor, if there is oil in it there is a problem. clean your MAS airflow sensor. Check all your breather hoses are connected and not blocked.