Abstract: An air-fuel ratio control system for an automobile engine of a type having a fuel injection system wherein at least two of parameters including the engine speed, the opening of a throttle valve and the negative pressure developed inside a fuel intake passage are utilized to detect the rate of flow of incoming air to be mixed with an injected mist of fuel to form a combustible mixture. The amount of fuel to be injected into the intake passage depends on the detected rate of flow of the incoming air. A composition sensor for detecting the concentration of an exhaust gas component is also provided for controlling an EGR control valve for controlling the recirculation of a portion of exhaust gases from an exhaust passage into the intake passage.

Abstract: An air-fuel ratio control system for an automobile engine of a type having a fuel injection system wherein at least two of parameters including the engine speed, the opening of a throttle valve and the negative pressure developed inside a fuel intake passage are utilized to detect the rate of flow of incoming air to be mixed with an injected mist of fuel to form a combustible mixture. The fuel injection system includes a fuel adjusting device so designed as to provide, when the engine operates within a particular operating region, the combustible mixture of an air-fuel mixing ratio lower than that to be supplied to the engine when the latter operates within the other operating region than the particular operating region.

Abstract: An air-fuel ratio control system for an automobile engine of a type having a fuel injection system wherein at least two of parameters including the engine speed, the opening of a throttle valve and the negative pressure developed inside a fuel intake passage are utilized to detect the rate of flow of incoming air to be mixed with an injected mist of fuel to form a combustible mixture. The amount of fuel to be injected into the intake passage depends on the detected rate of flow of the incoming air. A composition sensor for detecting the concentration of an exhaust gas component is also provided for controlling an EGR control valve for controlling the recirculation of a portion of exhaust gases from an exhaust passage into the intake passage.

Abstract: Exhaust gas recirculation means by which recirculated exhaust gas is supplied into a portion of a carburetor that is downstream of the venturi section of the carburetor, whereby fouling of easily blocked elements in the upstream portion of the carburetor is avoided, and in which supply of exhaust gas into the carburetor is in opposition to a supplementary supply of air from the atmosphere or from a portion of the carburetor which is upstream of the venturi, air and exhaust gas being supplied through a common port into the carburetor. The pressure of exhaust gas being comparatively high, the supplementary supply of air is steadily decreased as the amount of recirculated gas is increased, whereby the air-fuel ratio of a mixture supplied to an engine is decreased and the mixture is enriched in a manner required when exhaust gas is recirculated.