Abstract: A second spark is triggered, after a first ignition spark. The initiation overvoltage of the second spark is detected. The overvoltage and the occurrence or the non-occurrence of a failure of ignition of the air/fuel mixture prior to the second spark is deduced, according to whether the overvoltage is greater or less than a predetermined threshold voltage. Application to the protection of a chamber containing an oxidation, reduction catalyst for the exhaust gases of the engine.

Abstract: An electronic device for detecting and correcting pinking in an internal combustion engine by changing the ignition displacement of the internal combustion engine which comprises a vibration pick-up mounted on the internal combustion engine providing a signal to a band-pass filter for selecting a frequency band corresponding to pinking vibrations and a comparator, the output of which provides a signal for altering the ignition displacement of the engine and the two inputs which receive the output from the band-pass filter after it has undergone different treatments in two parallel channels, one channel comprising an integrator followed by an amplifier and the second channel preferably comprising an integrator, therebeing provided a gate between the band-pass filter and the two channels, which gate is only open for a predetermined angular zone during operation of the internal combustion engine.

Abstract: In an internal combustion engine ignition system having a knock sensor to back-off the ignition advance at the onset of pre-ignition knocking in the engine, the sensor is activated only during a fraction of the power stroke of each piston and the activation is achieved by processing of the ignition triggering signal rather than by incorporation of position sensors on the drive shaft of the engine/gearbox combination. The signal-processing device includes first stage means to generate a signal which is shifted by a constant time relative to the signal which it receives, and second stage means which generates a signal which is shifted relative to the incoming signal by a time corresponding to a constant angle of rotation of the engine (to take into account engine rotation speed) and these stages define the beginning and the end of the periodic signal required for control of the vibration sensor.