Originally Posted by Andy
Same thing with my volvo. I chased all the turbo control valve lines and replaced them all with silicon. Is your volvo automatic? From what I could gather the characteristics of the automatic volvos were slightly different and didn't go full boost until something like 3rd or 4th gear. Something about putting less wear on the tranny. I don't know if that applies to your 850 or not.
I know my s60 t5 is suppose to make 15psi from the literature I have read on the topic and for some reason I don't go past 10 psi. The best answer I could find was that it was a dealer thing and sometimes factory to limit the boost on the automatics.
It is auto. I need to research that, buy a few spare transes, and figure out a way around it.