Volvo4dv8
I was able to adjust the boost pressure to the desired range by connecting only the PTrans and using a pressure guage listening for the clicking of the 3 way valve. If I remember it also took some road testing to get it just where I liked it (a hair shy of fuel cutoff). So I have no doubt that this ECU can handle the pressure I want, it just can't handle the knock sensor at the same time. My 3 way valve seems to be operating correctly now but early in this grand experiment it would just flutter off and on even at idle. The way to check for a good 3way valve is to listen for an audible click when the ignition is turned on or the APC is powered up. I sure wish that APC/Volvo website was still in existence. My APC unit is producing the boost I want now, it just does not have the knock protection that made it so attractive in the first place.