I had a 300 miles drive today and the following occured while back in the city :
Once I stopped at a light Idle RPM was stuck at 1200
Inserted Gear (it's a tiptronic ) took it out and rpm was back at 800
After that I got a Low oil pressure while stopped in a jam with gear inserted, I started noticing RPM went intermittently as low as 600 and less with obvious pressure drop.
while stopped again after that it did 600-800-600-800 with a regular timing, like 2 seconds 2 seconds.
I got a couple of more low oil pressure signals due to the very low RPM the car was getting at while stopped or simply taking the foot out from the accelerator pedal at very low speed.
I did not notice nothing particular while moving, pressure is as usual while accelerating.

Wile arrived I checked oil level (OK) and the engine and noticed a low buzzing sound (like a cicada) while taking the engine up to 1500 2000 RPM by hand.
That noise does not seem right...

I'll take the car to my mechanic.
Any clue ??

 

You might want to look up some of the threads regarding the Idle Stability Valve (ISV). It may need to be cleaned.

JNeteler

 

Thanks Jneteler, had it cleaned it today in 20 minutes, it was very dirty.
It seems like the problem has gone.