This morning driving to work, I noticed the RPM needle was hovering at 750, then it would dip to maybe like 650-ish then go back up. I turned the stereo off and I could here a humming sound then it would cut out a little then go back to normal. While driving it seemed fine.

Anyone else experience this? Fuel Pump maybe?



525i btw.

 

Owners here on the forum have experienced similar symptoms while their alternator was on the way out...

Might want to look into that.

Good luck!

 

Thanks, I'll get that checked at.

 

Had this exact issue in my 550...

Completely went away when I had the brake vacuum recall done. I was leaking a decent amount of oil around the pump and I'm guessing it may have been messing with the vacuum pressure and causing the idle to fluctuate when the car was stopped. When driving, there were no noticeable issues.

As, the 6 cylinder doesn't have the vacuum pump issue, I'd check around for a vacuum leak elsewhere, maybe a disconnected hose or someplace where air can be entering/escaping the system.

/jack