Fairly frequently when Iamcruising on the highwayor accelerating lightly from a stop, usually while the car is in lower RPMS (1000-2500) the car makes this low pitched vibrating noise. It's an automatic, and it almost sounds like a manual sounds when it's bogging out (but not as loud).Even if I'm coasting on a flat road and start accelerating Lightlyit makes this noise. It usually only lasts a couple of seconds or until i let off the gasthen goes away. It's noticeably lower in pitch than the regular engine noise. I just upgraded to a APR R1 DV and installed a K&N Filter. Too me it sound like the intake box is resinating. any help or suggestions would be greatly appreciated.

 

hmmm check the tensioner on the serpentine belt the bearing might be on its way out

 

ill be sure and check that out. my audi is still under warranty, but because i installed a APR R1 DV will they give me s*^T about my warranty? thanks again and keep the idea comming.