Air Injection: Description and Operation

PURPOSE
The Secondary Air Injection (AIR) system controls emissions during the first 20 to 120 seconds of engine operation by forcing air downstream into the exhaust manifolds to oxidize the Hydrocarbons (HC) and Carbon Monoxide (CO) created by running rich at start up.

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

OPERATION
- The PCM requires Engine Coolant Temperature (ECT), Intake Air Temperature (IAT) and Engine Speed (RPM) inputs to initiate Secondary Air Injection function.

- When the engine is started, the strategy will determine when to enable the EAR The PCM signals the Solid State Relay and the AIR Bypass solenoid, after a 10 second delay, to begin system operation. Once the catalyst is lit-off, the PCM then signals the Solid State Relay to stop Air Pump operation and the AIR Bypass solenoid to stop the vacuum supply to the AIR Diverter valve(s).

- The Solid State Relay provides the start-up signal and will switch this high current required to operate the Air Pump.

- The AIR Bypass solenoid applies a vacuum to the AIR Diverter valve(s) causing it to open and to allow air to flow into the exhaust manifolds.

- The function of the Splash Cap is to provide the Air Pump with a source of dry air.

- The Electric Air Pump delivers the required amount of air which controls emissions during engine operation. Air is forced into the exhaust manifolds to oxidize the Hydrocarbons and Carbon Monoxide created by running rich at start up.