Abstract: A throttle control system including a throttle valve shaft and a throttle valve mounted at a middle portion with the shaft being rotatably carried on a support and spring-biased in a direction to close the throttle valve, and an operating lever and a control lever connected to said shaft. A first lever is fixed to the throttle shaft, and a lost motion lever is carried on said shaft and is capable of engaging the first lever. The operating lever is capable of engaging the lost motion lever. The relative positions of the first and the lost motion levers are established so that they are engaged with each other when the lost motion lever is rotated in the throttle valve-closing direction and the relative positions of the lost motion lever and the operating lever are established so that they are engaged with each other when the operating lever is rotated in a throttle valve-opening direction.

Abstract: An apparatus is disclosed for controlling an opening angle or a position of a throttle valve on complete firing in an internal combustion engine until the said engine has shifted to a situation of warm-up after the said engine started and the complete firing thereof was sensed. The control apparatus is so constructed that the throttle valve is closed at high speed to a predetermined opening angle which has an intermediate value between a starting position and a warming-up position when complete firing of the engine is sensed, and thereafter the throttle valve is driven to close until it reaches the warming-up position at a relatively low speed.

Abstract: A mixture control apparatus for a carburetor which precludes otherwise possible occurrence of fluctuation in the opening angle of the throttle valve even when the engine operation happens to fall near the boundary between the cold state and the hot state. The electric motor for driving the throttle valve is prevented from moving to the side of reverse rotation thereof from the side of normal rotation thereof past a home position after said engine has been changed to its hot state and unless a stop of said engine is detected.

Abstract: A mixture control apparatus for a carburetor which precludes otherwise possible occurrence of fluctuation in the opening angle of the throttle valve when the engine operation happens to fall near the boundary between the cold state and the hot state, a stepping motor for driving the throttle valve is prevented from hunting near the boundary between the cold state and the hot state of the engine by conferring hysterersis characteristics upon the set value for discriminating between the cold state and the hot state.

Abstract: An internal combustion engine fuel injection control apparatus is disclosed in which a basic fuel injection signal for light load is calculated as a function of the manifold pressure when the engine is operating with a light load, and a basic fuel injection signal for heavy load is obtained with the revolution number and the throttle valve position as the parameters when the engine is operating with a heavy load. The engine load condition (light or heavy) is decided in dependence upon the throttle valve position or the manifold pressure. The circuit employed for switch-over from a heavy load to a light load or vice versa preferably has a hysteresis characteristic.