Hissing noise

[99YELLOWGT99]

When my car is at idle there is no noise, but when i give it a little gas and the revs get around 1500-2000 there is a weird hissing noise. It sounds like is coming from the back of the engine. Maybe around the plenum not really sure. Has anyone else had this and what could it be. Its really annoying.. any help would be appreciated....

 

[urban96]

sounds like it may be a vaccume leak, u check all your hoses?

 

[Mr GT 02]

When my car is at idle there is no noise, but when i give it a little gas and the revs get around 1500-2000 there is a weird hissing noise. It sounds like is coming from the back of the engine. Maybe around the plenum not really sure. Has anyone else had this and what could it be. Its really annoying.. any help would be appreciated....

Did you just install a aftermarket intake? If, so It could be just the sound of all the xtra air being sukked in (Which would be normal). But if not....its prolly a VACUUM leak like the guy above me said.....

 

[99YELLOWGT99]

Thats sounds like what it would be...when i get a freakin day off im going to check them.. thank guys...

 

[zimkhan]

I have a 2001 Mustang Saleen, and very similar issue. Car runs great, but this annoying hissing noise that goes with the rpms. Press gas hissing starts at 1500, let go, hissing goes away.

Seems to come from underneath the driver side dash, around the steering column / pedals. Tested all exhaust, vacuum leaks, hoses etc, nothing leaks. What is the sound !?!

Here is a video of it:

Imageshack - mvi0969.mp4