Ignition control method and / or injection in a gasoline engine has Prechamber

The invention relates to an ignition control method and / or the injection for each cylinder (1) of a gasoline internal combustion indirect injection fuel engine of a motor vehicle, the engine comprising n cylinders (1) referenced 1 to n, the two cylinder combustion cycles (1) of consecutive references being offset by a period P, the cylinders (1) being supplied with air via an intake manifold (7) connected in each cylinder (1) via an intake duct (8), the rotation of the motor is measured using a measuring system (15) of the motor rotational angle. The method includes, upon detection of a failure of the measurement system (15) of the motor rotational angle, to determine the combustion top dead point according to failure from time intervals (d) predetermined depending on the engine speed, the engine speed is itself determined based on the time interval (T) between two consecutive extreme pressure in the intake manifold (7) and then controlling the ignition and / or injection according to the dead point high combustion thus determined.