Air Injection: Description and Operation

AIR System:

SYSTEM OPERATION

The AIR system is used to reduce carbon monoxide and hydrocarbon emissions. The system, under certain conditions, adds air to the exhaust manifold. When this air meets the hot exhaust gases inside the manifold, combustion continues, further oxidizing the HC and CO in the exhaust. These pollutants are then converted into carbon dioxide and water vapor. The additional heat energy released helps to bring the catalyst up to operating temperature sooner.

The AIR system consists of an air pump, air switching valve, ECM controlled vacuum switching valve, check valve, air injector manifold, and connecting hoses.

AIR Pump W/Pressure Relief Valve:

AIR PUMP

The AIR pump is a belt driven positive displacement vane type pump which is permanently lubricated and requires no periodic maintenance. It has an integral pressure relief valve to prevent damage to the system should the system become plugged. The pump supplies filtered air from the air cleaner to the air switching valve where the air is diverted either to the exhaust or back to the air cleaner.

Air Switching Valve:

AIR SWITCHING VALVE

The purpose of the air switching valve is to direct the air from the air pump to the exhaust system or to divert it to the air cleaner, as needed. The valve is vacuum operated. When vacuum is present at pipe #1, the valve blocks the air cleaner port and opens the port to the exhaust check valve. In this state the AIR system is operating. When vacuum is present at pipe #2, the valve closes the port to the exhaust check valve, and diverts pump air to the air cleaner. Vacuum should not be present at both pipe #1 & #2 at the same time.

AIR Manifold:

AIR INJECTOR MANIFOLD

The air injector manifold distributes the pump air to the individual exhaust ports in the cylinder head.

Check Valve:

CHECK VALVE

The check valve is a one-way diaphragm valve which prevents exhaust gas from escaping into the AIR system when the system is not operating, or in the event of a pump or system failure.

Vacuum Switching Valve:

VACUUM SWITCHING VALVE

The vacuum switching valve is an electrically operated vacuum valve which directs control vacuum to the appropriate chamber of the air switching valve. In its normal (de-energized) state, the valve is open between the source vacuum port (Y) and control port Z, while control port X is vented to the atmosphere. Vacuum is applied to pipe #2 of the air switching valve and pump air is diverted to the air cleaner. When energized by the ECM, the valve opens the source vacuum port (Y) to control port X, and vents control port Z to the atmosphere. In this position, control vacuum is applied to pipe #1 of the air switching valve, allowing pump air into the exhaust.