perrui

Hello,
I have second handed 2008 B7 A4 S-line quattro. I had this car about two years and I really loving it.
However, I found something strange. When I am driving at 35~40mph steady speed the rev jumps around between 1800~1900rpm. Also I can hear the sound that something is grinding. I wend to the Audi expert auto shop and asked to scan my car. The mechanic says there was no codes.
I'm seriously worried about my car. I'm guessing it could be the bad torque converter or bad transmission. If I have to change the TC or transmission how much is it gonna cost?
Thank you for reading.

Kris Hansen

Grinding is bad, you'll want to find out what it is. It does appear that most if not all of these things do the same rev surge, especially when the transmissions are cold. Mine is an 06, and does it till the trans is fully warm and has cycled through the gears.. It also seems to have more to do with requested load than anything.. I can get mine to stop it instantly by letting off, or applying more throttle. There is one spot early in the throttle travel that makes it happen worst...