Diesel engine with unit injectors and a catalytic converter arranged in the engine exhaust system, for reaction with uncombusted fuel. The injectors have spill valves, which in their closed position build up pressure in the injectors, and needle control valves, which in their closed position keep the needle valves of the injectors closed and which, when they are open, open the needle valves. The unit injectors have pump plungers, which are driven by individual cam elements whit a cam curve shaped so that a pressure is maintained in the injects for so long a period during one cycle that injection of fuel is permitted at least when an associated exhaust valve in the combustion chamber begins to open so late during the expansion stroke and temperature drop, that fuel after injection is not combusted in the cylinder but reaches the catalytic converted uncombusted.