Hissing from the dash at Idle

[wardevil260]

Hey guys,

I have an 04 Sti and when I'm at an idle I hear a hissing sound coming from the driver side dash. I can't hear it from under the hood, only when I'm sitting in it. I heard that it could be the A/C but I never use it so I don't think that could be the problem. Any suggestion helps. Thanks.

 

[HolyCrapItsFast]

Does your car have a factory boost gauge? If so what is it reading at an idle.

 

[wardevil260]

It's a Auto Meter boost gauge. It reads 8lbs of vac

 

[Spamby]

It's a Auto Meter boost gauge. It reads 8lbs of vac

You should be floating around 20inhg at idle. Sounds like a vac leak to me.

 

[HolyCrapItsFast]

Agreed! -8 psi is around -16 inHg which falls in the acceptable range but these motors are typically -20 as suggested. Verify that the gauge reads psi or inhg when in vacuum. Either way it is a low number