Reference Manual

Chapter 10: Emissions Equipment: A.I.R. System


These systems are used to reduce carbon monoxide (CO), hydrocarbon (HC) and nitrous oxide (NOx) emissions. They also heat up the catalytic converter quickly on engine start-up so conversion of exhaust gases will start quickly.

A dual bed converter is used. It consists of a three way catalyst (which controls all three emissions) in series with a two way catalyst (which controls only HC and CO). Both are in one housing. A pipe between the two converters allows air to be injected into the second (two way) converter to increase it's efficency to futher control HC and CO.

A.I.R. Pump Operation:

The system includes an air pump, a control valve, a check valve and neccessary plumbing.

AIR Control:

An intregal valve, called an air control valve assembly, is actually two valves or sections that have specific functions. Those sections will be referred to as air divert and air switching valves. Each is controlled by a solenoid vacuum valve.

Electric Divert/Electric Air Switching Valve (EDES), (5.0L)

This system uses vacuum operated, ECM controlled valve which combine both the divert function and the A.I.R. switching function in one housing.

5.0L VIN code Y and 9 engines use the same air control system as explained for EDES valves. However the air divert and the switching valves are separate valves.

Pressure Operated Electric Divert/Electric Switching Valve (PEDES), (3.8L)

Divert and switching functions are electrically controlled by the ECM. Pressure from the A.I.R. pump is used to operate the valve, and operation is completly independent of manifold vacuum.

Operation of PEDEDS Valve:

The relief valve operates to limit overall system pressure.

Results of Incorrect A.I.R. System Operation

Air Pump

The air pump is a positive displacement vane type which is permanently lubricated and requires no periodic mantainance.

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