Some kind of air leak

[David325is]

The problem I have makes a noise like an air leak. It is very loud and will only go away if I am at 3/4 throttle to full throttle. When I noticed the hissing noise I also noticed my idle changed to the idle similar to a V8 with cams. I am not sure what is going wrong.

-dg

[rs4pro3]

vacuum leak

[jlevie]

Sounds like an intake leak. The big duct that connects the AFM/airbox to the throttle body is a popular failure point. But leaks elsewhere in the intake are possible.

[gazellebeigem3]

I agree with the vacuum leak diag. If its that bad you may be able to find the source visually. If not, a good method is to get some starter fluid (or any flammable aresol) and spray it CAREFULLY around any joints or rubber with the car idling. When you hit the source of your leak, the idle will jump up suddenly. Then just go from there.

[StereoInstaller1]

Wiggling the hoses at idle is a good way to find them too. You will hear the change in sound.