When the turbo kicks in, I hear some "wshuuu" sound.
When I release the gas when turbo is running, I hear "pussh". I know the "pussh" is the BOV sound. But how about the "wshuuu"??? Is this normal??

The previous owner has done silicon hoses job. And I have just installed a boost gauga getting 16~17mm Hg of vaccum. I didn't do boost test yet. I will do it asap.

 

That is probably your charge relief valve venting the secondary boost. It will probably do this until about 4500 RPMs.

 

Or it sounds like you could have a boost leak check all your clamps to make sure they are snug and look for cracks in the rubber hoses and the plastic tubing.

 

Check the y-pipe coupler

 

the "wshuu" starts when the primary turbo kicks in...

 

Do the boost test, that will give you an idea on what's happening.

 

ok
i got 4/5 - 0 - 2/3(slowly developed) pattern in 3rd WOT
so what's happening?

 

you have a big leak... like everyone already said. try to find it. its not to hard.

 

Coupler on Y-pipe kept coming off on mine,so I made a bracket to keep it down.Ever since -OK

 

how to check the leak???
check it with engine running?

 

You can either check it visually,or pressurize the sys.with an air hose or just with engine running and quickly and briefly reving up (don't over rev it) until the turbo kiks in, you should hear it then.

 

i will try to rev the engine and hear where it leaks..
but it seems that there's no leak when gear is in neutrual...

 

you will not build enough presure for it to leak in nutrual. needs to be under load. do a visual inspection by ripping the entire intake down and doing a very close inspection by bending pipes and looking for cracks.

 

You should see like 3-4 psi even in neutral,and if the sound is heard when it stars to build a pressure on primary as you state,than you should hear it.
Of cause it's better under load......
But if the leak is on charge pipes(3")than it should be enough....

 

i did rev in neutual, but i didn't hear the wshuu sound~
i think i need to inspect visually~

thx

 

i had this same problem before, and i could never find out what the problem was. i changed all the vacuum hoses twice, and i checked all the charge pipes repeatedly. i think the best thing to do right now is to test all of your solenoids and actuators, which is something i never had the patience to do. that would probably be your best bet.

start with your turbo control and charge relief/control (sorry i forgot the name) actuators and solenoids. the procedure is outlined in the factory service manual.

or you can just go full non-sequential, which is what i have planned

 

any idea?

 

did you check the solenoids and actuators that i recommended above?

get yourself a factory service manual and do that, i would put money down that it is one of the electronic turbo control solenoids.

 

okok
should i replace them??
or there's way to adjust the???

 

I know where the problem is cause i had the same.you need to replace the intercooler piping .it is problably the upper one where it connects to the y pipe .sometimes you cant tell till u take it off ,but it is usually cracked around the hose clamps.just be ready cause you get a full boost !which is great and the sounds are gone !!

 

okok
here's a quote from my car's inspection by mazda dealer~~

"Air duct from intercooler to turbo lifts off @ turbo and suck air when turbo engaged"

I think this is my leak problem, can someone interpret it to me?

 

As I understand it, it's that plastic/rubber black hose that connects from intercooler to the Y-pipe - it's common failure point of the turbo system. That's why I ordered Efini Y-pipe to avoid the problem completely

 

i will go check my car tomorrow~

so anyone have more ideas?

 

OK, the wshuuu sound comes from your BOV, and usualy the time you hear it is when you are crusing in highway or local when slowly accelerating, before the wshuuu sound starts is when you are gently stepping on the gas pedal while at that moment BOV is closing not to alow any air to be bypassed but to go strait to intake so at that moment when the BOV is closing it acts like a big whistle for a secong untill fully closed.

And that's the result of the wshuuu sound you are hearing.

If your boost is not OK and the wshooo soung lasts while boostign the whole time, then you may have one of the problems above... Otherwise don't worry.

 

One more thing, if you are reving the engine in one place you will not hear that wshuuu sound unless like I said in the other post the sound lasts while boosting the whole time.