ok please help here i have been fighting what i have thought of as a boost leak for a long *** time now.... Basically its about to drive me completely mad! i ran a pressure test today to 20psi and fixed all my minor leaks. It still does it! but only above 6000rpm. I talked to another evo owner today he has had the same problem also being 100% stock...... Basically when i hit 6000 rpm i get a loud hisssssssssssss sound could this be the boost cut or........... hell i dunno the car then drops to 15psi anything beyond that... but anyway please help im @ a loss here..... btw im on a Turbo XS HP mbc and a Forge Recir. Valve. Im having the exact same sound with the stock valve so i dont believe that is the source of the problem. I have tightend every clamp and rechecked and rechecked and replaced all the ones i was concerned about. The only thing i havent done is switch them all over to T-Bolts... will that fix the problem. Has anyone here had the same problem then corrected with switching over to t-bolt clamps. Thanks again and sorry for my half asleep rambling ***...

 

what spring are you using with the turbo xs hp mbc?

you're going to get boost taper, but not that much boost taper with the mbc.

how is your mbc hooked up?

what are you using for the boost gauge?

 

mbc on backwards.....?????

 

using an autometer boost gauge. The spring in the mbc i dunno its just the one that came with it. i have had the boost control hooked up to the turbo outlet and the bov both with the same results...

 

no i dont think its on backwards the boost source is facing the ball which then once boosted to the correct amount would cause the ball to be pushed over then letting air to the wastegate actuator... but like i said its an extremely loud sound of rushing air and the car seems to fall on its face....

 

o btw @ one time i was getting the same sound on the stock boost solenoid.... and tapering to 15 as well

 

Maybe your autometer is leaking boost. Seriously I doubt you went in the car when you tested the leak. Check the compression fitting.

 

had my fiancee sitting in the car checking for the sound of a leak and watching the gauge pressure..... and the sound is for sure coming from out side not in the car...... wish it was so easy as the compression fitting

 

Are you on a stock airbox and if you are did you ever remove it I am asking because I had the same problem like you what happened I did not put the airbox on the pin located on the chassis of the car so just be sure that you put the airbox back the way it was on the bottom of the airbox there is a hole so just be sure that the pin is in that hole of the airbox and you should be fine

 

I know you said that you did a boost leak down test, but double check your couplings. They tend to give out after 6k rpms, if they are faulty. Does it hold 20 psi steady all the way up to 6k? Also, when doing the leak down test are you disconneting the upper intercooler pipe from the throttle body?

 

yeah it holds 20psi pretty steady very little taper then all @ once good bye
yes im running the stock box but the pin is inserted..... im really out of idea's im guessing its T-Bolt time.....

 

hey
i think i had the samw problem
since you have the stock airbox
GO run without the snorkle
the part of the airbox that takes in air
drive without that
and see if it happens ok
go try now

 

mmmmm thats kinda odd why would that cause the problem???

 

just try it
the noise maybe be coming from the snorkle not sucking in any air for the intake
just try it
it could possibly work
go go go go

 

what explains the boost drop to 15psi???