Electric Secondary Air Injection System: Notes
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Electric Secondary Air Injection (AIR) system consists of an Electric AIR Pump (EAP), single or dual combination check air injection diverter (AIR diverter) valve(s), an AIR by-pass solenoid, a solid state relay, PCM, wiring and vacuum hoses. The following list of components and their specific operation corresponds to numbers in illustration. See Fig 1.
- PCM requires Engine Coolant Temperature (ECT), Intake Air Temperature (IAT) and Crankshaft Position (CKP) inputs to initiate secondary air injection function.
- When engine is started, strategy will determine when to enable Electric Air Pump (EAP). After a 5-10 second delay, PCM signals solid state relay and AIR by-pass solenoid to begin system operation. Once catalyst is lit-off, PCM then signals solid state relay to stop EAP operation and to close AIR by-pass solenoid from supplying vacuum to AIR diverter valve(s). For additional AIR by-pass solenoid or AIR diverter valve information, see AIR BY-PASS SOLENOID or AIR DIVERTER VALVE .
- Solid state relay provides start-up signal and will switch high current required to operate EAP. Input control to solid state relay comes from PCM. See Fig 2.
- AIR by-pass solenoid applies a vacuum to AIR diverter valve(s) causing it to open and to allow air to flow into exhaust manifolds.
- Vacuum check valve controls vacuum bleed-off to solenoid.
- Function of splash cap, if equipped, is to provide EAP with a source of dry air.
- EAP delivers required amount of air to control emissions during engine operation. Air is forced into exhaust manifolds to oxidize hydrocarbons and carbon monoxide created by running rich at start up. For additional EAP information, see ELECTRIC AIR PUMP .