I was under the hood today doing some routine stuff... I noticed a hissing sound coming from around the TB. I am assuming it's coming from one of the rubber hoses back there. Can anyone tell me what those lines are? There is one that is only about an inch long, if I put my hand on that hose the hiss changes. If anyone can help me put I'd appreciate it. Thanks.

 

i believe they are the vacuum hoses. i could be wrong though. maybe just replacing them would solve the problem.

 

from what it sounds-... the sound seems to be coming from the back of the intake manifold?

if so, it's the IAC. if you are having wierd idle issues, the IAC or the rubber hoses may need to be replaced.

the hissing might just be the sound of the iac doing it's job. but see what some of the other members say.

oh and be careful-... it might be a pissed off snake!

 

ive got 2 iacs sitting here. pm me if you want one. i have the hoses too i think

 

Yeah the sound is coming from behind the intake manifold. It's near a bosch part of some sort (the part with the 1" hose)
Is the IAC the thing that bolt into the valve housing or is that PCV? Thanks for all the input. And I'm pretty sure it's not a snake.... Hopefully soon there will be a Cobra on the driveway though.

 

i had the same problum, and it was the intake manifold gasket, check that and buy a pheno spacer which will help keep the intake mani cool and replace the gasket at the same time.

 

The IAC will always make a hissing sound. Don't worry about it unless you actually detect a leak. It makes the sound because it has a blade in it which regulates air flow. If you put your hand around the hose that connects to the intake manifold you won't be able to hear the hissing anymore. I noticed it after I put on my CAI. It's really nothing to be worried about. It's the IAC doing it's job.

 

That's exactly what it's doing DrivingNaked! So it's nothing to be concerned about? That's good. Thanks for the help!

 

hiss? dtn, I'm not sure what your talking about but if their is an audible hiss that typically means a leak. If you pinch a hose and it goes away that hose in leaking.

I always though the iac was more of a electrical buzz. Doesn't it do it even when the cars not running?

 

No it only makes the hiss while running. The hose making the noise doesn't bubble with soapy water, so I guess it's not leaking...