I want to buy a car but it has a problem. It's a 2007 Chrysler 300C 3.0 CRD and the car doesn’t rev past 1100 rpm and smokes white. The current owner said that he changed the turbo and EGR, checked and cleaned the fuel rail and injectors, and it still has the same issue.

Then he found out that the previous owner gutted/emptied the exhaust and there was no new tune/remap for the DPF delete. Could this be caused by the missing tune, or could it be something worse? I’ve never heard of a limp mode that wouldn’t allow you to rev past 1100 rpm. He said the car would still drive up to 30–40 km/h.

What could it be?