Throttle Opener Control System: Description

The Throttle Opener Control System (TOCS) slightly opens the carburetor throttle valve during deceleration to reduce hydrocarbon (HC) emissions. During deceleration, the intake manifold vacuum rises and the quantity of air/fuel mixture is not sufficient for normal combustion to continue. Thus, a large amount of unburned hydrocarbons is emitted. To prevent this, the throttle opener control valve opens the throttle valve and supplies an adequate amount of air/fuel mixture to maintain proper combustion.

The system consists of a servo diaphragm, vacuum control valve, throttle opener solenoid valve, speed detecting switch and amplifier. On models with automatic transmission, an inhibitor switch and relay are used in place of the speed detecting switch. In addition, some models have an altitude corrector fitted to the vacuum control valve to automatically regulate the operating pressure in response to the altitude at which vehicle is operated.