Air Injection: Description and Operation

Air Injection Reactor System:

To reduce HC and CO emissions, this system injects air into the exhaust ports to accelerate oxidation. The air management valve (AMV) introduces air from the air pump to the check valve on the air manifold or diverts the air to the atmosphere. AMV mode is controlled by the electronic control module (ECM). The ECM calculates AMV mode using various inputs, including coolant temperature and throttle position. A hose supplies intake manifold vacuum to actuate the AMV.

AIR PUMP

The air pump consists of the pump body, cover, rotor, vanes and relief valve. It is belt-driven by the engine.
Air is drawn through the air cleaner and suction hose into the pump suction chamber. As the rotor turns, the vanes trap the air and carry it to the outlet chamber and then to the air manifold.
The relief valve is closed by spring tension under most conditions. When pressure exceeds spring tension, the valve opens to release excess air that would otherwise surpass pump outlet air pressure.

AIR MANIFOLD AND AIR INJECTION NOZZLES

Pressurized air flows from the air pump, through the check valve and into the air manifold. When directed by the system, air is injected into the exhaust manifold through nozzles near the exhaust valves.

AIR MANAGEMENT VALVE (AMV)

The air management valve controls air flow from the air pump and is operated by intake manifold vacuum. When manifold vacuum is higher than specified values, air flows from the pump to the check valve. When manifold vacuum drops below specified values, the AMV closes and air is vented to the atmosphere. The ECM controls the solenoid that switches vacuum on and off to operate the AMV.

Check Valve:

CHECK VALVE

The check valve is designed to allow air to pass through in only one direction. The valve is pushed open when the pressure of air supplied from the air pump overcomes the valve spring tension and closes with the counterflow of exhaust gas from the manifold. This protects the air pump and hoses against damage when air supply from the air pump is stopped due to a broken drive belt or when backfiring occurs.