Throttle Opener System: Notes

The throttle opener is controlled by a solenoid valve, control valve, and speed sensor. When vehicle speed is above 20 MPH, the speed sensor causes the solenoid valve to open and allow manifold vacuum at the control valve. When the manifold vacuum exceeds a preset value (which occurs during deceleration), the valve opens and the throttle opener opens the throttle a small amount.

When vehicle speed drops below 10 MPH, the speed sensor closes the solenoid valve, control vacuum drops, and the throttle positioner vacuum is relieved through an orifice. Carburetor return spring tension closes the throttle.

Fig 1: Throttle Control System Diagram (All Models)

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Throttle Control Valve

Courtesy of AMERICAN HONDA MOTOR CO., INC.