Auxiliary Air Valve (Idle Speed): Description and Operation

The air valve located on the intake manifold consists of thermo wax, springs, and valve. When the engine is cold, it sends the air into the intake manifold without letting it pass through the throttle valve to increase the engine speed, and thus the engine is warmed up.



OPERATION

When the engine is cold (or engine cooling water is lower than about 7O° C (158° F), the thermo-wax contracts.

Air Valve (open):

In this state, the valve opens by the spring force, allowing the air to be drawn into the intake manifold. Thus the amount of intake air increases even when the throttle valve is fully closed and the engine speed rises to the fast idle state which is higher than the idle speed.

Air Valve (closed):

As the engine is warmed up, the thermo-wax expands gradually, then the piston pushes the valve gradually, and the amount of air passing through the air valve decreases and so does the engine speed. When the engine cooling water temperature reaches about 70° C (158° F), the valve is fully closed and the engine speed is back to the normal idle speed.