Air Injection: Description and Operation

Fig. 6 Pulse air valve type air injection system:

Fig. 7 Air injection ports:

This system, Fig. 6, is used to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions by injecting air into the exhaust manifold. The system consists of an air filter with an additional fitting, air injection cut-out valve, electro valve, air distribution manifold, 4 pulse air valves, diffuser plate on which the pulse air valves are mounted and a specially designed cylinder head incorporating passages into the exhaust valve ports to permit air injection, Fig. 7. The air injection system uses the existing vacuum in the cylinder head exhaust ports. A predetermined amount of filtered air is drawn in through the air distribution manifold and to the pulse air valves. The pulse air valves then introduce air injection to each exhaust port. The exhaust ports in the cylinder head are subjected to variations in pressure and vacuum due to the evacuation of the exhaust gasses and cycling operation of the engine. When the exhaust valves are open, there is no air injection. When the exhaust valves are closed, exhaust gasses remaining in the exhaust manifold and exhaust pipes retain a certain discharge speed and momentum, creating a momentary vacuum within the exhaust ports. This vacuum brings about the necessary air injection.

The Air Injection system injects air into the exhaust ports during initial start-up of the engine and while coolant temperature is below 104°F. When coolant temperature increases above 104°F, the air injection cut-out valve closes, stopping air injection to the exhaust ports.

Fig. 1 Evaporative emission control (EEC) system:

Diagnosis

PULSE AIR VALVE TYPE SYSTEM

1. Start engine and disconnect electrical connector wire No. 157 from thermo switch as shown in Fig. 1.
2. Alternately touch the other thermo switch terminal wire No. M157 with the disconnected wire.
3. A ``humming'' noise should be heard coming from the pulse air valve or diaphragm movement should be noticed through the upper portion of the pulse air valve. If ``humming'' noise is heard and diaphragm movement is confirmed, connect wire No. 157 to thermo switch.
4. If the operation is not satisfactory, check the operation of the electrovalve, its electrical current supply, and the vacuum hose connections.
5. If the tests in step 4 are positive, the valve is at fault and should be replaced.

INSTALLATION NOTE: The arrow which is on the body of the valve should point to the Pulsair valves. The arrow should not be visible when facing the engine.