What causes a diesel engine to backfire and blow white smoke?

A diesel engine backfires and emits white smoke primarily due to incomplete combustion. This can occur when there is a problem with fuel injection, such as incorrect timing or a malfunctioning injector, leading to unburnt fuel entering the exhaust system. Additionally, an overabundance of fuel, a poor air-fuel mixture, or issues with the engine's compression can contribute to this phenomenon. Cold temperatures and a failing glow plug system may also exacerbate the problem, particularly during startup.