Hey guys. Im working on a buddies f550 and just took it for a test drive and when i stepped on the go pedal it was doggy till around 1500 rpm (only gaining 5psi boost) then it got a kick in the *** and took off and finally started gaining boost. Also it had a hi pitched sound like a jake brake or something was engaged but the truck doesn't have one?! This doesn't seem normal to a Cummins guy. Thanks in advance!

 

Sounds like the wastegate may be your issue. Some people just swap in a '15 turbo and fuel pump if the turbo is toast.