I have this "hissing" sound that gets louder with boost. It's been there for a while, thought it came from the intake. Changed my hoses and got a leak check but sound is still there, even replaced the BOV. Now boost is down to .9bar and Dynojet baseline run is 240 from 298. Friend said turbo is toast...appreciate some feedback please.

 

long shot here but have you checked the throttlebody shaft seals?

 

Thanks, will check. Forgot to mention that a tuner installed a restrictor pill and it was fine for a few months, then started spiking to 1.8 bar after a few trackdays. Took the pill out and it would spike to 1.6bar and settle down to 1.2bar. Then this happened.

 

check the compressor on the turbo, look for damage.

 

is the hissing from under the hood or sound like it is in the dash?

 

@ Murf- yup, next step is to take a good look at the turbo.
@ Sabastian458 - under the hood, really sounds like a hose but leak check was neg.

 

did you do a boost leak test??

 

Pull the turbo and check for shaft play and make sure the turbine wheels spin freely. If it is in on the way out usually you would see odd signs in either your exhaust or AFRs if you are tuned with it correctly.

+1 on the boost leak test.

 

he said "leak check" but my hunch is....boost leak test wasnt really done.

your friend is wrong about your turbo "hissing", you shouldnt be taking car advices from him lol. blown turbos will howl like your cars haunted hehe. "hissing" = leaking air. boost leak test will show the location right away.

 

snakes on an Evo???

 

+1

 

sounds like you are running off the wastgate. check your boost control. if you are ecu tuned try adjusting that and see what happens.

 

I wish, all I need is a mongoose to fix LOL.

If a boost leak check means running 2 bar of compressed air from the hot side of the IC to check for leaks, then yes we did a boost leak check.
I took off the intake pipe and checked the turbo impeller, found no play and spin was good. Will probably pull out the whole turbo to check the hot side. Will also try a wastegate swap.

 

You should do a boost leak test from the inlet of the turbo. I would check the J pipe off the turbo for a leak.

 

are you on a stock intake box?