hey guys and gals it's been awhile since I've posted anything. Here's the issue I'm having. Over the past 2 days ive noticed a decrease in boost and power also not all the time but a lot of the time when I get into the car it will kinda stumble and the car sound like the exhaust gets louder. The boost with full throttle will cap at 11psi and anything over 4500 will be around 8.8 to 9 psi. There no codes no engine light. I'm getting all my reading thru my scan gauge 2. Before all of this I was seeing my boost around 15-17psi consistency.
the only thing I have done to the car is a aem intake and that's been on for over a year.
Now things I've already looked at.
Diverter valve boot,spring, good shape no tears o rings look good.
wastegate acelarator tight and very little play
cleaned hot side boost pressure sensor cleans mass air flow
checked all hose clamps on turbo piping from turbo to intercooler thru to the throttle body. All seam good.
Turbo spins free and there's no side to side or front to back play.
oils just changed and full.
I've been looking all over the internet and nam but can't find anything close to what I'm experiencing. hope some one can help

 

The diaphragm in your bypass/diverter valve may have a tear in it.

 

I'm going to pull it apart again and look I'm hoping that all it is

 

This was 5th gear wot at 4500rpm. I let the car climb up from 2500rpm so i know there should have been boost more boost than that.

 

Pulled the diverter valve out and to rips or tears of the boot and is functioning properly. Could it be the vacume pump?