Federal Civic Hatchback with 1500 Eng. & Man. Trans.

When manifold vacuum exceeds the preset level of the throttle control valve (which happens during deceleration), vacuum is applied through the control valve to the throttle opener diaphragm. This opens the throttle a fixed amount for improved combustion.

When vehicle speed is below the preset speed of the speed sensor, throttle opener solenoid valve A is closed and no vacuum reaches the control valve.

When vehicle speed is above the preset speed of speed sensor, throttle opener solenoid valve A is opened. When engine coolant temperature is below the preset temperature of the thermosensor or engine speed exceeds the preset speed of the engine RPM sensor, throttle opener solenoid valve B is closed so that manifold vacuum is applied to the control valve without leakage. When throttle opener solenoid valve B is opened, manifold vacuum is bled through an orifice in the valve, decreasing the opening time of the throttle control valve.