My ‘94 850 Turbo wagon has 200K miles and is running well with the exception of low turbo boost. The car has a noticeable loss in power under full throttle and has a peak turbo boost of ~20% on the right side of the dash turbo gage. My wife normally drives this car and I remember when I was driving that the turbo gage would travel ~75% into the turbo range under full throttle.

I replaced the PVC system 45K miles ago and all vacuum hoses. All hoses check tight. The engine burns virtually no oil.

The car idles fine and has no engine codes stored. It just drives like a non-turbo 850.

I posted a similar thread here years ago where I found a loose hose. Not this time.

Any tips would be appreciated.

When I had this problem it turned out to be a pin hole in the blow off valve diaphragm. To check, there is a black 2 foot long vacuum line from the turbo to the front of the intake manifold. Unplug this line, clean it a bit, and suck on it. If it doesn't hold vacuum, you found the problem. The solution is not a fun job! You will need to invest in a 10mm ratchet/wrench to get the 3 bolts out. IPD has a nice kit.

If the BOV holds vacuum, then it is just a matter of looking for a loose connection in the inter-cooler piping.

Excellent and easy enough! I like to give IPD a little business from time to time so I’ll order up a replacement from them tomorrow.