Heavy Engine Load

When engine speed sensor detects engine speed at or below specified value, solenoid valve is opened which transfers intake manifold vacuum to throttle opener. Throttle valve is slightly opened by throttle opener and opener lever located on throttle valve shaft. Engine will then run at a speed resulting from new throttle valve opening. When a heavy load condition does not exist, throttle opener system stops working and engine runs at normal speed. The engine speed sensor used in the deceleration spark advance system is usually used in the throttle opener system.