Air Injection Control Valve: Description and Operation

4-156/2.6L ENGINE
These deceleration devices are incorporated to decrease HC emissions during vehicle deceleration. The system comprises of an air switching valve (ASV), coasting air valve (CAV) and a deceleration spark advance system (DSAS).
In order to decrease HC emissions emitted during vehicle deceleration, the ASV which is activated by carburetor ported vacuum, cuts off fuel flow to the bypass holes and pilot outlet by supplying additional air into the low speed passage. The CAV, which is activated by carburetor ported vacuum also, supplies additional air into the intake manifold. The DSAS advances ignition timing, while the ignition timing is usually controlled by carburetor ported vacuum as well as engine speed.
Activation of the ASV & CAV is interrupted by opening the solenoid valve, when the engine speed sensor detects engine speed below 1300 RPM, in order to maintain smooth vehicle operation and to eliminate engine stall.