Abstract: A combustion engine comprises at least two combustion chambers and an ignition system having a spark device (11, 13) forming an electrode gap and a charging member (20) for accumulating the electrical energy necessary for generating a spark in the electrode gap. The combustion chambers are in the compression stroke according to a predetermined sequence. During a first engine revolution, high voltage pulses are supplied at a high frequency to all spark devices (11, 13). The spark voltage in the electrode gap of each spark device (11, 13) is measured for each spark. Based on the measured spark voltage of the different spark devices, the combustion chamber that first will be in the compression stroke is determined by means of an electronic control unit (3). Based on the predetermined sequence and the knowledge of the combustion chamber that first is in the compression stroke, fuel is injected in the combustion chamber that next will be in the compression stroke.