THis is bizare. Sitting at an idle (throttle body compleatly closed) I can hear very loudly a constant vacuum sound. Like a loud sucking coming from the air filter. I can't figure this out. I know I should hear some but not this loud. And it doesn't go away when reving either. I concidered an intake manifold leak so I pulled the intake mani off and replaced the gaskets and sealant and NO differance. The car does seem to have a rough idle and feels like it's missing at low RPMs too. Only code the car is throwing is 0336 (Crank position sensor). Not sure if any or all of this is related.

Any thoughts?

 

Mine does the same thing at startup its almost a whistle sound I thought it was from having a CAI.

 

My car makes the same "sucking air" sound at idle, mainly heard when I'm outside the car. When I'm driving I don't hardly hear it due to the exhaust/radio and road noise. My car has had head/cam long tube Kooks w/Y pipe Corsa catback, throttle body and I'm running an OEM SS Ram Air box. My car runs GREAT and throws no codes, so I know I don't have a vacuum leak. It didn't do it until I did the engine work/headers & exhaust. I just marked it up to the amount of increased air flow going through the intake.

 

May be the aftermarket TB too I haven't tried seeing if it still does it without the air intake.

 

Mine does it constantly; no vacuum leaks, no intake leaks, just the normal sound for my car at least. (I Figured it was due to a completely de-baffled WS6 hood, Fernco Coupler, Z06 MAF.... essentially a straight path from the outside to the TB (other than the airfilter))

 

Yes but that loud? With the throttle body blades closed the only air getting pass should be threw the IAC valve.... thing sounds like a goddamned industrial suck fan all the time.

 

Oh mine's VERY loud; Hell, almost sounds like a blower on my car.

 

could be bad intake gaskets on there....
Easy way to check is spray some wd-040 along the side of the intake and your valve covers see if the sound goes away and see if the engine idle changes or spray starter fluid that works even better it should idle a little better if that is your problem...
I had this issue before and we couldn't figure it out and we did that and found out the gaskets were bad...

 

Also forgot to add could be wrong torque on your intake bolts... or on the tb gasket could be bad spray it would that as well and that will tell you if thats bad...