Abstract: A throttle valve opener for a throttle valve in the intake passage of a vehicle engine is actuated by suction pressure from the intake passage, the suction pressure being weakened by introduction of atmospheric air during certain operating conditions of the engine. Suction pressure for operating the throttle valve opener is cut off when the vehicle speed or the engine RPM exceed predetermined values, or when the engine's cooling water temperature rises above a predetermined limit. This system controls deceleration of the engine to reduce exhaust pollutants without adverse effects on the drivability of the vehicle.

Abstract: A method and apparatus for exhaust gas recirculation for an internal combustion engine in which exhaust gas is recirculated through a recirculation passage connecting the exhaust passage of the engine and the intake passage of the engine. A vacuum-response type recirculation control valve is disposed in the exhaust gas recirculation passage to operate in response to vacuum detected at a vacuum detection port located in the intake passage in the vicinity of a throttle valve. A vacuum tank is connected through a solenoid-actuated change-over valve to the vacuum passage interconnecting the vacuum detecting port and the recirculation control valve, the vacuum tank being in communication with the intake passage downstream from the throttle valve through a check valve.