6.6 Duramax Excessive Black Smoke
Problems
Several things could be causing black smoke in your 6.6L Duramax:
Problem: Dirty air filter (causing a restriction in the air inlet system)
Problem: 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)
Problem: Clogged EGR valve (causing too much backpressure into the cylinder) – particularly in early Duramax trucks
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