HELP PLEASE: 1jz not holding boost!!!

[88cameron88]

I have a stock turbo 1jz.
ran about 11psi on stock boost.
i just fitted a dual stage boost controller and hks fuel cut defender
now i have upped the boost.

it boosts to 15 or 16 psi straight away but if you keep into it it goes back to 10psi and just sits there. it WONT hold 15psi for more then a second.

what could be causing this and how do i fix it???

thanks in advance fellas

[88cameron88]

ok just took the car for another drive. i can wind the boost controller as far as it goes, and the boost spiked to 20 then sat on 15 through throttle.

then i did it again and it just sat on 10!!!

its got me stuffed

[Draven]

sticky/stuck wastegate or vac leak?

[88cameron88]

blocked the blow off valve today and they car boosted fantastically, just like it was supposed to. for about 10 minutes. now no matter how far i wind the boost controller its still only making about 10-13psi again

anyone had trouble with the wastegate actuators on stock 1jz turbos before though??

[Hendo]

Ive heard one guy had cracked housings so the waste gate wouldn't seal properly