Idle Speed/Throttle Actuator - Electronic: Description and Operation

Electronic Air Control Valve (EACV):

The Electronic Air Control Valve (EACV), located on top of the intake manifold next to the air cleaner housing, opens the air passage from the air cleaner case to the intake manifold in proportion to the intensity of the electric current received from the ECU. The EACV performs four functions. It controls air-fuel mixture as follows: the carburetor air-fuel mixture is basically calibrated on the richer side of the stoichiometric ratio, and the air supply through the EACV dilutes the mixture for controlling the mixture close to the stoichiometric.

In shot air mode, the ECU receives signals of vehicle speed, engine coolant temperature, intake manifold vacuum and engine speed. Shot air is induced from the EACV when the manifold vacuum increases suddenly except when the vehicle is moving at a very low speed with the engine coolant temperature below the normal operating level.

During deceleration the ECU receives signals from the MAP sensor, TW sensor, speed sensor, vacuum switch, gear position switch, and ignition coil, and identifies the conditions which indicate deceleration. The ECU transmits the electric current to the EACV which opens and supplies air into the intake manifold. For hot engine start control the ECU receives the signal of engine coolant temperature. When it is higher than the normal temperature, the EACV is activated to supply air into the intake manifold before the vehicle speed exceeds the set speed.