Hey listen i just got my car and im a total newbie but this is whats up i need some advice!! I have a 2001 A4TQ when i give my car gas it sounds as though there is almost a hole in my exhaust. It sort of hisses i know its not my turbo it sounds like blowing noise could there be a hole in my exhaust. It is also coming from the front of my car and it only does it when im driving and give it gas. I also have noticed that when i start my car or sometimes when its idling there is a clicking noise it sounds like something might be wrong with my fan. if you put your tongue to the roof of your mouth and blow it makes kind of a purring sound and thats what it sounds like. if i give it a little gas when i hear this noise it goes away. If i slightly excel when im going under 10 mph and then let off i will hear it for a few seconds! If is not a clicking sound and its not metal on metal. just that funny purring sound!! I would love any input that anyone has. Thanks!!!

 

I'd guess the hiss IS your turbo, and the other noise is probably your fuel injectors.

But all I can do is guess w/o hearing it myself.

 

check your oil level!

 

hissing noise is probly boost leak. check the a4 forum. i just posted about mine. you can easily check it from underneath the car.

 

EVAP canister purge valve would be my first guess but it shouldn't be that loud, next would be the flex on the exhaust system