Help please Cat 315 calibrating prv selenoid

Hello i have a problem with a 315 excavator i installes new engine and new hyd pump i habe 4500 psi on my new pump which is fine, but machine has lack of power engine doesnt die some one told me its my PRV whats the procedure to replace it for a new one how do i calibrate the PRV machine is cat 315 its a 1995 serial 6xm i get the oarts from the 6ym because mine its Jap and doesent appear on the sis.
Thanks very much y appreciate your help!!

Help please Cat 315 calibrating prv selenoid