This section is all about diesels and smoke, whether your truck has a running problem or not.

Black Smoke:
You'll find that in diesel applications black smoke is actually a normal and naturally occurring thing.  For example lots of industrial equipment, dump trucks, busses, and big rigs all belch out large amounts of black smoke and it can be considered "normal."  However, black smoke is usually a symptom of engine that needs some basic maintenance (most likely an injector rebuild) but it can also be caused from an number of other reasons including low engine operating temperature, extreme or heavy loads, altitude, or the need of a tune up.  Black smoke is caused by unburned fuel.  When fuel is unburned or partially combusts in the exhaust, it creates black smoke.  Furthermore, black smoke can also be caused my improper injection pump timing usually indicating the fuel pump is too far advanced.  Black smoke and unburned fuel can also increase your EGTs.

White Smoke is typically caused by an injection pump that is timed too far retarded.  There are other factors that can cause white smoke, for example sometimes when going down hills for extended amounts of time at low RPMs (ie off-road), my truck will leave some white smoke, or at idle in the morning.