Air Injection: Description and Operation

AIR System:

SYSTEM DESCRIPTION

This system is used to reduce Carbon Monoxide (CO) and Hydrocarbon emissions. This system under certain conditions, adds air to the exhaust manifold to continue combustion after the exhaust gas leaves the combustion chamber. It also heats up the catalytic converter quickly on engine start-up so conversion of exhaust gases will start quickly.

The A.I.R. system includes:

^ An Air Pump:
A belt driven pump on the front of the engine and supplies the air to the system. Intake air passes through a centrifugal filter fan at the front of the pump, where foreign materials are separated from the air by centrifugal force.
^ A Control Valve:
Air flows from the pump through an ECM controlled valve (called a ECT valve) through check valves to either the exhaust ports or the converter.
^ 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.
^ Necessary plumbing.

EAC Valve:

CONTROL VALVE DESCRIPTION

ECT VALVE

The ECT valve directs the air from the air pump to either the engine exhaust manifold ports or to the air cleaner.

When the engine is cold or wide open throttle condition, the ECM energizes the solenoid on the valve and air is directed to the exhaust manifold ports. When the coolant temperature increases, the solenoid is de-energized and the air goes to the air cleaner which acts as a silencer also. At higher engine speeds, air is directed to the air cleaner through the pressure relief valve even though the solenoid may be energized. There should be no air going to the exhaust manifold ports during "Closed Loop" operation.

During engine decel, when there is a rise in the manifold vacuum signal, air is directed to the air cleaner.

If the "Service Engine Soon" light is on or the engine is operating under a rich condition the solenoid is de-energized and the air goes to the air cleaner.