Air Injection: Description and Operation

A.I.R. System Operation:

SYSTEM DESCRIPTION
This system is used to reduce Carbon Monoxide (CO) and Hydrocarbon (HC) emissions. It also assists in the heating of the catalytic converter on engine start-up. This allows the conversion of exhaust gases to begin much sooner.
A dual bed converter is used. It consists of a three-way catalyst, which controls all three emissions including Oxides of Nitrogen (NOx), in series with a two-way catalyst, which controls only HC and CO. Both are contained in one housing. A pipe between the two converters allows air to be injected into the two-way converter in order to increase its efficiency and further control HC and CO. Air flow is directed by a control valve, which diverts air to the atmosphere, exhaust ports, or catalytic converter.



The A.I.R. system includes:
1. An Air Pump:
A belt driven pump on the front of the engine supplies the air to the system. Intake air passes through a centrifugal filter fan at the front of the pump, where foreign material is separated from the air by centrifugal force.
2. A Control Valve (EDV):
Air flows from the pump to atmosphere or to the exhaust ports. An electric solenoid controls the Electric Diverter Valve (EDV). The ECM controls the ground circuit in order to energize the solenoid.
3. Check Valves:
The check valves prevent back flow of exhaust into the pump in the event of an exhaust backfire or pump drive belt failure.
4. Necessary plumbing.

Air Injection Reaction (AIR) Control Valve:

ELECTRIC DIVERTER VALVE (EDV)
The Electric Diverter Valve (EDV) provides an air diversion to the air cleaner housing under wide open throttle and high temperature. When the ECM de-energizes the solenoid in the lower portion of the EDV, it prevents manifold vacuum from entering the vacuum chamber. The spring tension, in the vacuum chamber, forces the diaphragm upward, causing air to flow into the air cleaner. During wide open throttle, intake manifold vacuum is low. The low vacuum is unable to compress the internal spring. This directs air to flow into the air cleaner housing. During high engine speeds, excess air is exhausted to the air cleaner through the pressure relief valve. Air diversion to the exhaust ports is controlled by the ECM grounding the EDV circuit.