2012 Kenworth Paccar MX-13 Turbo issues

Is the engine still stock? Or have certain parts fell off?

 

Check power and ground to the vgt actuator. Also check the data link. Should have 120 ohms in the actuator and 120 ohms on the engine harness.
I have seen ones lose power to the actuator and not code out for anything. With it being modifed, fault codes dont mean too much any more as lots of times they throw false ones or not throw as many as they should be. Kinda gotta approach it old school. Also a test drive while monitoring helps to narrow it down.

 

Sounds like the engine brake is stuck

 

I had a Mercedes 4000mbe engine that did the same as you described but that engine had an exhaust brake. The flapper valve in the exhaust closed allowing no flow and this in turn results in the turbo not spooling up. I'd have them check the exhaust from the valves to the turbo. Somehow the flow is restricted.

 

The more I think about it the flapper valve was after the turbo so I'd say check the exhaust system from the turbo back for any restrictions.

 

I'm not familiar with the Paccar motor. Does it have an exhaust brake or a traditional Jake brake?