Air Injection: Description and Operation

PURPOSE
The air injection system is used to reduce hydro-carbon (HC) and carbon monoxide (CO) emissions.

OPERATION

Air Pump Air Filter:

Air is drawn into the pump through a rubber tube that is connected to a fitting on the air injection pump filter housing. Air is drawn into the filter housing from the front of the vehicle with rubber tube. This tube is used as a silencer to help prevent air intake noise at the opening to the pump filter housing. An air filter is located within the air pump filter housing.

Air Injection System:

Air is then compressed by the air injection pump. It is expelled from the pump and routed into a rubber tube where it reaches the air pressure relief valve. Pressure relief holes in the relief valve will prevent excess downstream pressure. If excess down-stream pressure occurs at the relief valve, it will be vented into the atmosphere.

Air is then routed from the relief valve, through a tube, down to a "Y" connector, through the two one-way check valves and injected at both of the catalytic convertors (referred to as downstream).

The two one-way check valves protect the hoses, air pump and injection tubes from hot exhaust gases backing up into the system. Air is allowed to flow through these valves in one direction only (towards the catalytic convertors).

Downstream air flow assists the oxidation process in the catalyst, but does not interfere with EGR operation.