Abstract: Apparatus for controlling the supply of fuel to an internal combustion engine. The apparatus includes a hot-wire air flow meter and a smoothing circuit connected electrically to the output of the flow meter, said circuit eliminating pulsations present in the output signal of the flow meter, thereby preventing corresponding fluctuations in the air-fuel ratio of the mixture admitted to the engine.

Abstract: A control point of a closed loop mixture control system for an internal combustion engine is varied by extending the duration of a signal representative of the deviation of air-fuel ratio from a preset value, or by alternately supplying an engine speed representative pulse sequence in opposite polarities to a first and a second output terminal. An integrator is connected to respond to the duration-extended deviation signal or connected to the first and second output terminals to effect integration of the alternatively supplied, opposite-polarity pulses to generate a stepwise voltage waveform. The integrator output is used as a feedback control signal which fluctuates about a level differing from the present value to shift the control point of the closed loop corresponding to said difference.