Good Evening,
I need some help. I have a 2009 A3 with 70k on it. I was driving the home the other night and it started making this loud noise almost like a belt squeal. I had 1/4 mile to go. During that time the noise would go in and out several times. When I got home the noise was not there anymore. At this point I thought it was a belt slipping(maybe a pulley locked up). I had my girlfriend start the car so I could look and see what pulley was sticking. At this point there was no noise and nothing sticking but the car was running very rough. I called and talked to a certified Audi mechanic and subsequently had the car towed in. Once in the shop the car started making the noise. The mechanic noticed that the check engine light was on read the codes and the only thing coming up is random misfire. He put new coils and plugs still running rough and making the noise. The car even makes the noise with the belt removed and car running. Can anybody out there help me get my car fixed?

Thanks
John