the basis of engine speed and induction tube air flow rate and transmits these control pulses to the electromagnetic fuel injection valves 32 when the engine braking detection circuit 25 which monitors the engine speed and the throttle valve position detects the condition of engine braking it actuates the ignition timing shifter circuit 22 which causes a shift of the engine timing toward retardation i e late ignition in order to perform the readjustment from late ignition to normal engine timing as depicted in the diagram of fig1 the timing shifter circuit 22 must be coupled to the tacho generator 12 the circuit 22 also requires throttle valve position data so as to initiate the cancelation of late timing when the throttle valve is opened this latter connection however is not absolutely necessary in particular if engine braking is defined to include the condition of closed throttle and idling in addition to closed throttle and above idle speeds depending on the magnitude of the signal of the timing shifter circuit 22 the timing controller 20 shifts the moment of timing in the direction of retardation from the time which corresponds to the instantaneous values of engine speed and pressure and the synchronizing circuit 23 translates this new value into a particular timing angle the fuel enrichment circuit 33 which feeds into the pulse generator circuit 30 includes a component which recognizes the termination of engine braking furthermore it contains a timing circuit which permits the provision of an enriched fuel air mixture for a predetermined period of time following the pulse control circuit 30 is a clipper circuit.