I noticed a hissing noise coming from the front of my engine while testing the PCV valve yesterday. It was hard to pinpoint, but it is definitely coming from the front near where the ignition coil wire assembly/protective cover mount to the motor. When I pinched the hose on the left front of the motor, the hissing decreased. Is this normal? Perhaps I am hearing hot gases passing through the passage leading from the hose to the PCV valve? Also, the PCV valve doesn't click when I pinch the tube, at least I cannot hear it. I did get a check engine light for the emissions system after doing so though.

 

I know this post is old, but I'm searching through and finding the same issue on my TL. Hissing noise and fast idle. If I pinch the PCV hose, the idle drops to normal. Otherwise I get an erratic idle, and a P0507 High Idle CEL. Did you eventually fix this?

 

What's preventing you from locating this air leak by noise?
You haven't replaced the valve covers recently, have you?

 

yes, i did do the valve covers. they were cracked so i bought new ones.

 

Easy diagnosis. Your valve covers are junk, buy new or used OEM ones.

 

yah, that's my thought too. fucking a.