Author Topic: Annoying hissing sound that isn't a boost leak (Read 4788 times)

MikkiJayne · « **on:** December 13, 2007, 02:25:39 pm »

Hey everyone,

I put a 1Z TDI in my Corrado a few weeks ago, and I'm getting a really annoying hissing sound from the engine. Its definitely not a boost leak, since I've had one of those already and it blew oil everywhere! Thats not happening any more, and it has plenty of power so I'm confident the boost is staying where it should be.

The noise is dependent on throttle position - it gets louder with more throttle. Over 2500 rpm it goes away over ~50% throttle, and over 3000 it goes away almost completely, so I think it must be something thats controlled by the ECU.

I unplugged the EGR solenoid and it made no difference - no codes or anything. I haven't tried unplugging the N75 yet....

Any thoughts welcome cos its a really really annoying noise!

Mikki x

MikkiJayne · « **Reply #1 on:** December 18, 2007, 07:15:28 am »

Surely someone must have an idea what this is? :?

jtanguay · « **Reply #2 on:** December 18, 2007, 12:38:08 pm »

that almost sounds like turbo whine to me...

MikkiJayne · « **Reply #3 on:** December 18, 2007, 05:36:16 pm »

Mm its not that - I can hear the whine in the background. This is a loud hiss like air going in or out of something. It would make sense that it was a boost leak except for it going away at full throttle :?

blkboostedtruck · « **Reply #4 on:** December 18, 2007, 05:50:16 pm »

is it anywhere with the heater controlls? like a vacume leak?
Duane

MikkiJayne · « **Reply #5 on:** December 19, 2007, 03:28:49 am »

Good idea but no. I don't have any vac stuff under the dash as I don't have A/C. The noise is definitely from the engine as you can hear it outside the car. Unfortunately it only happens under load so I can't make it happen just sitting on the driveway

clbanman · « **Reply #6 on:** December 19, 2007, 06:01:03 am »

If it's throttle dependent, would it possibly be a small leak/crack in your intake/tubing?

jtanguay · « **Reply #7 on:** December 19, 2007, 01:21:16 pm »

its probably a manifold leak then. i know a guy with an old audi 4k 5cyl engine that has a manifold leak... it sounded like it had a turbo :lol: