On my way home from work today and I noticed a strange exhaust noise above 3500rpm. High pitched (i've usually got a low deep turbo exhaust note) and only when I should be on boost. Took it for a spin aound my block when I got home (rather hilly). Had it in 2nd and my foot to the floor and couldn't get it to boost above 0.8psi. I should get above 5psi (which is still a bit low for my liking- but it's on the list of things to do). I'm running an s4 turbo ex-factory warranty block -only 10000kms on it and a 1 year old s4 turbo with a ported wastegate. There's also a wolf 3D v4 in there. The engine seems fine when not on boost - I can slowly rev it to 7500rpm and it sounds sweet, but soon as I go hard at it, I get a wierd exhaust noise and no boost.

Any thoughts would be greatly appriciated - turbo warranty ran out 1 month ago

 

check hoses. I had the same problem.. It turned out to be the intercooler pipe closest to the firewall. Also check all your other hoses.

 

May be kinda simple, but have you checked all of the IC piping from the turbo to the throttle body? Could be a boost leak.

 

You aint got an exhaust noise there bud.... sounds like a pressure escaping noise.

if you rev it SLOWLY, your boost controller is going to keep the wastegate open and the turbo won't spool up, hence, the car is under vaccume and you're not hearing the noise.

Stick yer beak under the hood, and have a buddy floor it at idle, this should close the wastegate and get a small amount of pressure built up in the system, you may be able to locate the noise that way.

Check to make sure your blow off valve is connected, check ALLyour piping, and if that dont work, check for gaskett leaks Check the UIM>LIM gaskett, the mating surface at the plenum, and the exhaust gaskett at the block/manifold and Manifold/turbo area.

Mine made the same noise, and only when the turbo was trying to boost..... turned out to be a blown UIM/LIM gaskett.

Your idle will most likely be crappy cause a boost leak usually turns into a vaccume leak when not under boost!

If you can't find it by looking/listening,,, break out the carb cleaner and start spraying around while the car is idling... if you spray a junction, and the car dies soon thereafter...... bingo.. you found your leak.

 

Thanks for the suggestions, sorry for the slow response needed sleep. I'll let you know what it turns out to be.