Abstract: Four-stroke diesel engine with unit injectors and a catalytic converter in the engine exhaust system for catalytic reduction of nitrogen oxides in the exhaust, the unit injectors have pump pistons, each driven by an individual cam element with a cam curve, which has a first cam ridge effecting injection of fuel during the ordinary injection phase of the engine, and a second cam ridge which achieves so-called post-injection in the engine combustion chamber during the exhaust phase of the engine, for supplying vaporized fuel to the catalytic converter.