Variable Engine in Idle

HI
I was having some trouble with a vibration in the engine and low idle. The mechanic increased the idle (said it was low). But now, I noticed when I am driving and parked the idle fluctuates (the needle on the RPM is moving and there is some kind of vibration). The vehicle has around $67K miles on it. Is this normal or should I have it checked further?

Not normal and probably should be checked further. Sounds like a sensor failure, which should throw a code, or a reprogramming is needed.

What make, model and year do you have? Did you buy it used? Has it had questionable gas put in it? Is it throwing a code or not? Was it run in an urban environment, more short trips that long highway ones?

I had the same problem, with an 07 530 with the standard 6 cylinder engine, 62K miles. Ugly idle +- 100 rpm, no codes. Not much reason to take long trips.

Assuming no codes thrown, start with the simple stuff. If you bought it used (former owner perhaps using crappy gas), or if you had to get gas in an iffy location, or you just used in around town, get three bottles of Techron, and add one to your next three tanks of high quality premium.

Second, take it out on the highway and run it to 5K+ rpm by downshifting to a lower gear. Leave it that way for 10 minutes. The car is fine at that RPM for hours, but this'll clear out some of the accumulated crap that collects throughout.

These two items helped me a lot, clearing up most of the iffy idle. I was considering the Idle Control Valve, but the problem cleared up most of the way with the above.

Could be a DSA valve. Needed mine replaced around 100k. I had similar symptoms which were a rough idle after the engine had fully warmed up. Engine speed would fluctuate between 600 and 800 RPM (M54 - 530i). Did not throw any messages in iDrive until I was taking the car in for repairs (what a coincidence huh).