I have an 01 a6 2.7T with 62k miles. At the beginning of the winter I noticed a whining noise when I turned on the car. It continues for about 30secs to a minute in length. Then you can hear it almost whine down and stop. It doesn't sound like the turbos because i've had them checked and they were completely fine. They were refurbished when the car had 29k miles on it. Does anyone know what this noise is from and is it normal?

 

Probably the secondary air injection pump... For 2.7T it is located behind the engine and can be accessed after removing the air intake. Labor is not that extensive but the part is about $300 or so. Here is a post of a guy who rebuilt it.

http://forums.audiworld.com/showthread.php?t=1727056