Ok i have a isx15 smokes alot under a load cac was leaking changed it changed egr valve an egr cooler egr temp sensor cleaned the pipes on the intake manifold an the sensors on the intake lots of soot still smoking under a load
It could be a bunch of things. Did you check all the connections from the turbo to the CAC and what color smoke is it? I am sure you know the different colors of smoke but just checking.
Black smoke found the bottom hose an the hose going to turbo leaking changed both with new clamps got a little more power but still black smoke in a pull on a hill under pressure it stops when u back off the pedal.