Abstract: The quantity of air inducted in a four cylinder Otto engine with fuel injection and an inlet throttle for each cylinder is determined by indirect measurement, unaffected by atmospheric pressure variations. The induction air pressure is measured by a transducer located between one of the throttles and its associated cylinder inlet valve, and the pressure is sampled, using an electronic gating system responsive to engine speed, within a precisely defined range (preferably 15.degree.-25.degree. after bottom dead center) of engine crankshaft angle.

Abstract: A solid state ignition system for an internal combustion engine is controlled by a spark advance means in relation to one or more parameters affecting spark quality. Supply battery voltage is monitored by the spark advance means whereby the latter generates control signals that regulate primary ignition current so that the latter attains a predetermined level before primary ignition current is interrupted.

Abstract: Automatic control of spark advance in an electronic ignition system for an internal combustion engine is effected by using a first electromagnetic pick-up cooperating with a protuberance which is phase-displaced on a rotary part (flywheel) relative to top dead center by the maximum advance angle required, and a second pick-up which cooperates with peripheral teeth on the rotary part. Pulses from the second pick-up are counted during a predetermined interval (T) initiated by a pulse from the first pick-up to provide a count which is stored as a reference value representing the required spark advance angle, this stored reference value being subsequently compared with the number of pulses from the second pick-up counted with the commencement of the next pulse from the first pick-up to provide a spark-triggering pulse upon parity of the number of these subsequently counted pulses with the reference value.