I bought my 94 hatch with a b20 swap turbo and the guy told me it was tuned and was pushing 12psi and this was my first turbo car so i didn't notice the psi on the boost gauge and when i was under the hood i accidently hit the boost controller which ended up turning it some so i thought i turned it back but when i go full throttle it will boosted then cut out so i turned it down some and now when i go full throttle it doesn't cut out and it reads about 7-8 psi, but i also notice when it boost it will go to about 8 psi then drop down some. So why can't i do more then 7-8 psi, do i need a aftermarket map sensor? or what? Sorry i don't know the exact type of turbo but all i know its a Mitsubishi turbocharger internal wastegate with about 55 trim.

 

It was probually boost cut. When it was tuned they tuners set a boost limit if you will and when you try to go over that it dosent let you. providing the tuners set up a boost cut. If not it could be whats called breaking up eaither by fuel or spark. And when it jumps up to 8 psi and than back down it's probually boost creep/spikes. stock map sensors can read up to 10 or 11 psi i'm having a brain fart

 

If your hitting boost cut it would feel like you hit a wall.

 

yeah when i go full throttle and it cuts out it feels like i pushed on the brakes then i let off some and it takes off, it only seems to do it when i go full throttle but if i'm slowly going full throttle it doesn't cut out.