Hey,
My boost is only building around 5PSI. I upgraded the BCS to the ARD TCV and it did not fix it. My next idea is to test the CBV diaphragm. I have read about using a hand vacuum pump to test it. Can someone tell me what I should pump it up to and then what it should hold at? Thanks

 

I think you should take out the three bolts holding in and physically inspect it. Much more informative. Next, you should look for boost leaks by pressurizing the system. The most common place is the boot attached to the throttle body, underneath.

 

I went from over boosting to under boosting.

https://volvoforums.com/forum/volvo-...oosting-78922/

 

Don't forget to reset the computer. It still may be in a safe mode.

 

Boxpin, okay I will just take it out then. My hoses are silicone mishimoto, but I looked them over and they all look good and tight. Last night I noticed my boost "fluttering" which I think is a pretty sure sign of the cbv but I will look it over

 

If you read the thread I linked above, it should have links to videos etc., that showed what all I went through. Chances are, you have a tear in a turbo tube somewhere letting pressure escape. There is another high possibility that the ECU is dialing back the boost due to an error pending in the ECU.