Air Diverter Valve: Description and Operation

Fig. 3 Air switching valve (combination switch/relief valve):

Exc. RWD Models with EFI
This valve, Fig. 3, directs air injection flow to the exhaust ports or to the downstream injection point. The valve also regulates air pump output during high speed operation. When air pressure reaches a predetermined level, some of the air pump air is vented to the atmosphere through the silencer. Initially, air is injected at the upstream location as close to the exhaust valves as possible. As engine temperature increases, EGR and oxygen sensor systems will begin functioning. When this occurs, the air injection point will be switched to the downstream location. On 1982-88 engines, except 1983 L4-135/2.2L and 1983-88 4-135/2.2L engines, the valve is controlled by manifold vacuum with a CCEVS valve and/or a vacuum solenoid. On 1983 L4-135/2.2L and 1983-88 4-135/2.2L engines, the valve is controlled by manifold vacuum with a CCEVS/CVSCO valve and/or a vacuum solenoid. When the engine is cold, a manifold vacuum signal is sent to the valve which directs air injection to the exhaust ports. As engine temperature increases, the CCEVS valve or CCEVS/CVSCO valve shuts off the manifold vacuum signal to the valve. Without the vacuum signal, the [1][2]air switching valve (combination switch/relief valve) directs air to the downstream location.