Air Injection: Description and Operation

Air Injection System:

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 (PEDES):
Air flows from the pump to atmosphere or to the exhaust ports. Two electronic solenoids control the Pressure Operated Electric Divert/Electric Switching Valve (PEDES). The ECM controls the ground circuit in order to energize the solenoids.
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.

A.I.R. Control Valve:

ELECTRIC DIVERTER VALVE (PEDES)
During cold operation the port solenoid, located inside control valve body, is energized opening the port valve and allowing air flow to the exhaust ports. During warm or normal operation the port solenoid is de-energized and the divert solenoid, located inside control valve body, is energized closing the port valve and forcing air flow to the catalytic converter. In divert mode both solenoids are de-energized which opens converter valve allowing air to flow to atmosphere. Air flow to atmosphere takes the path with the least resistance, out the divert/relief tube.