Air Injection: Description and Operation

Purpose
The Electric Secondary Air Injection (AIR) System has an electric air pump which controls emissions during the first 20 to 120 seconds of engine operation. The AIR system forces air downstream into the exhaust manifolds to oxidize the hydrocarbons and carbon monoxide created by running rich at start-up.

Components
The AIR system consists of an Electric Air Pump (EAP), a combination Check and Air Diverter (AIRD) valve(s), an Air Injection Bypass solenoid, a Solid State Relay, Powertrain Control Module (PCM) and connecting wires and vacuum hoses.

Operation
When the engine is started, the PCM signals the Solid State Relay and the Air Injection Bypass solenoid to begin system operation, after a few seconds delay. The Solid State Relay provides the start-up signal and switches the high current required to operate the EAP. The EAP provides air until the catalyst is lit-off and can oxidize and reduce emissions.
The Air Injection Bypass solenoid applies a vacuum to the AIRD valve(s) causing it to open, allowing air to flow into the exhaust manifold through the inlet. The inlet contains a splash cap that prevents dirt and water from entering the EAP Once the catalyst is lit-off, the PCM signals the Solid State Relay to stop pump operation and the Air Injection Bypass solenoid to stop the vacuum supply to the AIRD valve(s)