So I rebuilt the motor. It runs great. Getting effiency code.grom aftermarket cat which ill take care of later on. But after about 125 miles of letting new piston rings seat in I finally started to give the car a little boost since I hadn't went over 5 pounds yet. Somewhere between 10 and 15 psi the BOV starts bypassing and then gets stuck open. The unit was on the vehicle when I got it and had a yellow spring installed. I have the spring kit so I took it apart checked all 3 o rings cleaned the seats and put some new high temp grease in with the red spring. Same result BOV bypass and stick open between 10-15 psi. Check and reinstall orings with blue spring this time with the same bypass and sticking again.
The o rings look flawless the piston cup does as well. All my vacuum lines are brand new and plumbed correct evidenced by my boost gauge holding steady 15-20 vacuum while cruising in low rpm.
This is my first turbo car ive messed with and am seeking advice on next thing to check before just buying the turbosmart BOV or any other parts.

Thanks

Edit: I'm still running stock tune. Upgraded intercooler. Aem intake aftermarket cat downpipe 2nd cat and resonater deleted with 2.5 inch downpipe back exhaust And colder plugs.

Am I limited to around 15psi on the stock tune and that be the reason my bov is bypassing at maybe 12 psi?

 

Since the valve was on the car when you got it, I would start by reviewing the instructions, and making sure its all installed correctly:
https://www.forgemotorsport.com/?download_id=51

 

I did since I had the entire engine apart and installed new vacuum lines. I downloaded the instructions when I was reinstalling everything. It functions flawlessly until around d 12 psi

 

Its possible the piston is getting borked inside the housing...

 

Edit: am I just limited to 12-15ish psi max on the factory tune? Ive been holding off on the tune because I've put about 9k in the vehicle including purchase price just to get it.yp and running right.
Worth spending 20$ on the service kit and see what happens?

Im trying to check things with a vacuum gauge and see if something is leaking somewhere.. like possibly the qastegate actuator leaking. Its been chilly and rainy lately so I've not been able to do much

Could my wastegate adjusting rod be too far out or too far in?

ive removed the forge unit and am going to order the service kit. With a Vacuum gauge on the bottom valve the unit will not hold vacuum. With gauge on top valve however it will hold vacuum.

I cant physically see any damage to the piston or housing that would cause an air leak but its happening

not the best picture but here's what im referring too. Covering the bottom hole i cant achieve any vacuum in the lower port. Its leaking around the piston