Method for igniting a motor vehicle combustion engine

A method for igniting a motor vehicle combustion engine, said method being implemented by an electronic control unit of an ignition circuit of a motor vehicle combustion engine, said ignition circuit comprising a transformer, comprising a primary coil and a secondary coil, and a spark plug electronically connected to the secondary coil of the transformer, the primary coil being capable of charging, and capable of discharging into the secondary coil, the discharge duration of the primary coil being predefined, the spark plug being capable of generating a spark during the discharging of the primary coil into the secondary coil, the method comprising:

• a) a step of requesting to start a combustion cycle of the combustion engine,
• b) a first phase referred to as “generating a main spark”, comprising:
• i) a step of activating the charging of the primary coil,
• ii) a step of continuously measuring the current in the primary coil during the charging of the primary coil,
• iii) a step of deactivating the charging of the primary coil and activating the discharging of the primary coil into the secondary coil for the predefined discharge duration when a measured current value received is equal to a predefined reference maximum current value,
• c) a second phase referred to as “generating at least one subsidiary spark” after the first phase, comprising:
• i) a step of activating the charging of the primary coil for a predefined charging duration,
• ii) a step of measuring the current referred to as the “repeat” current in the primary coil at the moment of activation of the charging of the primary coil,
• iii) a step of determining the difference between the repeat current value and a reference repeat current value,
• 1) if the measured repeat current value is greater than the reference repeat current value, a step of increasing the value of the discharge duration,
• 2) if the measured repeat current value is less than the reference repeat current value, a step of decreasing the value of the discharge duration,
• iv) a step of continuously measuring the current in the primary coil during the charging of the primary coil,
• v) when the measured current value is equal to a predefined reference maximum current value:
• 1) a step of deactivating the charging of the primary coil and activating the discharge into the secondary coil for the increased or decreased discharge duration,
• 2) or a step of deactivating the charging of the primary coil and activating the discharging of the primary coil into the secondary coil for the predefined discharge duration, a second request to start a combustion cycle of the combustion engine, a second first phase, and a second second phase in which the activation of the discharge into the secondary coil takes place for the increased or decreased discharge duration.