Power Valve Control System

With accelerator pedal at full throttle, throttle position switch will be turned on. Switch will turn on vacuum solenoid valve. This allows intake manifold vacuum to act on power valve. Since vacuum at wide open throttle will be almost zero, power valve will be open due to spring tension.

If coolant temperature is below 122°F (50°C), vacuum solenoid valve will again be turned on and manifold vacuum will act on power valve. Power valve will open or close in accordance with changes in intake manifold vacuum.

When coolant temperature rises above 122°F (50°C), solenoid valve is turned off. This allows vacuum from surge tank to act upon power valve. This will keep power valve closed except at full throttle operation.