Excessive Black Smoke
Problem: Several things could be causing black smoke in your 7.3 Powerstroke:
Cause: Dirty air filter (causing a restriction in the air inlet system)
Solution: Check the air filter and replace it if needed.
Cause: Incorrect fuel spray pattern or extra fuel dripping out of the injector (causing the ratio of fuel to air in the combustion chamber to be too high)
Cause: Stiction in the turbo (causing lack of boost pressure)
Solution: Treat with Stiction Eliminator