Its been a while now that my cars had this hissing kinda sound like air escaping from somewhere..i hear it its under the hood (no exhaust problems, checked). i think it might be the intake tube. The tube is conected to the intake manifiold, and a cone filter at the end. on the tube tho thers two holes, one for the air sensor,but whats the other for? it has a little nipple and it came wit a rubber thin hose but im not sure is it suposed to plug into somewhere of the engine/manifold? any helps. thanks

Was the noise there when you first put your intake on, and when does it make the noise. (all the time ,only at idle, only when your moving?)

well u cant reely hear it while driving but at idle you can. u know the 2 holes thats on an intake tube, one wit a nipple the other jus a hole for the air sensor. is the one wit a nipple supposed to be connected to some part of the engine/manifold or sumthing by a little hose?

anybody know?

hmmm take a pic cuz im kinda confused. i will take a pic of my setup which might help. i will post it up in an hour or two

Yea i saw the one you have its from autozone or whatever. I know that one of them is for the MAFS, not to sure about the other one, but as far as i know its cool. Cause when i had it on mine it made the noise at idle.

for the GT model, that hole is for a hose that comes off of your valve cover. but since you have an ST, nothing goes there. just go to autozone and buy a vaccuum cap bro, thats what i did.

but that hissing... its probably just the intake itself. mine hisses like a snake

ohh ok thanks

There are three holes in my induction pipe (HKS) one for the sensor the other two are located further along near where it joins the manifold. One is small 15mm ish 90 degree pipe that connects straight below the intake valve. This creates a heavy vacuum/sucking noise when not connected so check this for splits/connection, the other feeds around towards the actuator, its a small bore vacuum pipe check this too. Other check is the small pipe leading from the rocker to the intake manifold, the oil blow bypass, this is also under heavy vacuum.

Hope that helps

yeah once you get a valve cover there will still be a hiss sound but that is just the vaccum suction sound that it is supossed to make

on 6g celicas you should only have the temperature sensor plugged into the intake pipe, seal off everything else with vacuum caps. the oil breather connects straight to the intake manifold so those nipples become obsolete.