What causes black smoke in petrol cars?
Black smoke in the exhaust of petrol (gasoline) powered cars is caused by incomplete combustion of hydrocarbon fuel resulting in black carbon particles. Incomplete combustion is mainly caused by too much fuel for the amount of air available, or by fouled fuel injectors that don’t properly atomize the fuel. Too much fuel is caused by faults in the fuel injection control system that includes fuel pressure regulators, air volume and temperature sensors, and the engine control computer.