Can't lower boost

[jusroln]

I am having problems adjusting my boost level. I have a stock T25 and a Dejon Tool dual MBC. I'm building 15psi of boost by 2500RPM's and 1/2 throttle. I have the screw backed virtually all the way out on the MBC but 15 PSI is as low as I can get it to stick at. Any idea's why I can't back the boost down any further? Maybe a jacked wg actuator?

 

[clockworktoy]

Did you hook up the MBC correctly? you should be able to go below 15psi. Try running straight wastegate pressure and see what you come up with.

 

[toojung2die]

Simplest test: remove the MBC and connect the turbo to MBC output hose directly to the wastegate. You should see a significant drop in boost. If you don't then see if your wastegate actuator and wastegate are operating. Connect ~ 20 psi of air pressure to the wastegate actuator. It should move out and open the wastegate. Then disconnect the actuator arm from the wastegate and see if you get about 90 degrees of movement in the arm from fully closed to fully open.

 

[jusroln]

Thanks guys. I will try both suggetions tonight.

 

[DroopYeyeS]

Also check to make sure the spring in the mbc isn't stuck in the chamber. I had a similar issue that I couldn't get the boost down. Turns out the sring in my mbc got hung up on the outlet valve, and was forcing the ball to stay down. Just another possible answer.