Have a 97 3500. truck runs good, but unless boost is over 15lbs I do not have much power. If I do get smoke if I am in to high a gear low rpm. But unless boost is over 15lbs truck acts like I have no turbo. Afc spring and husing ajusted so it should have no effect. change fuel filters, and air filter. Not sure where to start, overflow valve? must be a way to diagnose other than throwing parts at it.

 

Check to see if you have a boost leak first. Check the intercooler to see if its leaking, as they fail as well.

 

Boost leaks and check that the waste gate isn't seized open, is this different from normal or new to you truck? How's your fuel pressure? ppumps need about 50+ i believe, AFC is all very important regardless of how its adjusted or improperly adjusted

 

Good idea to check the wastegate isn't opening prematurely. Honestly I would wire tie the wastegate closed or shut. Plug up the boost and line remove going from the afc (P7100 injection pump) to the turbo. No need for it.

The 12v lift pump typically are around 36 psi. The overflow fuel valve spring could be getting weak or a worn lift pump.

 

yes good idea to wire it shut as a bad actuator could allow drive pressure to open it to early, also have someone locally that knows about these to verify timing, they are not keyed so very easily can slip time