I have an 04 Dodge Cummins TD with Bully Dog. As I accelerate or if I am towing, the turbo will hit 16PSI then shut off, losing power and spitting black smoke. If I take my foot off the pedal it will come back and I can accelerate with turbo again, but as soon as it hits 16psi it shuts off again. The exhaust temp is only about 1100, and engine temp is good.

What could it be?

 

Sounds like ECM is defueling. Dont know much about BD. Do they have safeties built in that will defuel under high exh temps, coolant temps ect? Could be boost sensor malfunction also.

 

When you say shutting off you mean boost drops to zero? Check all your boots and intercooler! Power brake it and listen for a boost leak.

 

sounds like a boost leak to me follow what dangerous said and you should figure it out quick