I finally found out the problem where sometime i hit full boost and sometimes not.
it's my bov i have the hks ssqv and it has a problem whewre sometimes it doesn't close properly and sometimes does.
anyone know where i can go to fix this?

Typical issue with piston type BOV
When you get crap stuck between the walls of the BOV and the piston, it prevents it from moving (ie opening/closing)..spray some lub on it

or get rid of it and put the stocko back on

pull it apart (don't lose the srping!) and chuck some lube on the piston, move it with your hands to make sure it moves smoothly

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MY93 Impreza GX 1.8L, 0hp, 0nm

The HKS SSQV is not a piston type BOV, its a pull type BOV. It works COMPLETELY different to an ordinary piston type BOV.

There is a diaphragm attached to a shaft, with a large spring that holds the valve closed. The vacuum line is connected to a nipple on the rear housing.

When the throttle is closed, a large difference in pressure between the inner part of the valve and the rear chamber causes the valve to open. Once the pressure has been released, the pressure is equalised and the spring will close the valve again, and the valve will be held closed by boost pressure.

The valve has two stages. Lower pressure gear changes cause only the central primary valve (the purple bullet shaped part in the middle of the black piece) to pull away releasing the pressure through a small gap between the primary and secondary valve. High pressure gear changes pulls the valve open further, opening both the primary and the secondary valve.

The diaphragm in the BOV might be damaged if its leaking boost. Is your valve a GENUINE HKS valve, or is it not?? Genuine ones very rarely jam up or become damaged, unless the diaphragm is old and its cracked or split

Best thing to do is completely disassemble the BOV. This can be done yourself, there aint that many moving parts!

Wash each individual part with soapy water and rinse with fresh water. Inspect to see if any parts are damaged, and if they are, thats your problem and you'll have to replace the parts.

If its all good, lube up the main shaft of the piston with a bit of silicone spray, and reassemble. Coat the main diaphragm with a bit of silicone spray also to keep it soft and prevent it from drying out and/or cracking.

If you still have a problem with boost after you do all this, its more than likely not your BOV.

Like Joe has said above....!

9 times outta 10 I have pulled them apart to find the diaphram damaged or torn. I have never heard of spare parts, so unfortunately you're looking at a brand new one!

I've never seen the fuss about people avoiding piston style BOV's. Sure there's some not so good ones out there, but I've always personally been a big fan of GFB. Purchasing them from an authorised distributor usually also gives the luxury of a yearly service to prevent any 'sticking issues'. Not to mention they have ongoing R&D reviews of their products to constantly improve them... and hey, if your valve is damaged, you can order parts from Australia!!

the problem with piston bovs sticking is that before they close the induction goes back into vaccuum and the bov ingests dirty unfiltered air from atmosphere, now if your bov is getting enough crap in it to seize it up, i'd hate to see how much crap actually gets down inside your valves/pistons, its not like you can wash them in soapy water

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Long live the WRC