Air Injection: Description and Operation

SECONDARY AIR INJECTION (AIR) SYSTEM FUNCTION

- The Secondary Air Injection (AIR) System injects air behind the exhaust valves for 65 seconds during cold start at engine coolant temperature of 15°C to 35°C (58°F to 95°F). The additional air provided by the Secondary Air Injection Pump enriches the exhaust gas with oxygen and initiates after-burning. This after-burning shortens the amount of time required to get the Three Way Catalytic Converter (TWC) up to full operating temperature.

- The AIR system is activated by the Motronic Engine Control Module (ECM) (J220), operating the Secondary Air Injection Relay (J299), which in turn actuates the Secondary Air Injection Solenoid Valve (N112, change-over valve), and the vacuum-operated Secondary Air Injection Inlet Valve.

- In addition, the Secondary Air Injection System operates briefly each time the engine is started, and remains at idle up to max. 85°C (165°F) engine temperature. After a 20 second delay, the system is activated for 5 seconds and checked by the On Board Diagnostic (OBD) program.