Air Injection: Description and Operation

Secondary Air System







The Secondary Air Injection (AIR) system causes the catalytic converter to heat up more quickly, resulting in earlier operating readiness following cold start.

Principle
Due to over-enrichment of the mixture during the cold start phase, there is an increased amount of carbon monoxide in the exhaust. Secondary Air Injection (AIR) improves secondary oxidation in the catalytic converter and therefore reduces emissions. The heat produced by secondary oxidation greatly reduces start-up time for the catalytic converter, therefore improving exhaust quality during the cold start phase significantly.

Function
- In the cold start phase, the ECM -3- activates the Secondary Air Injection (AIR) pump -1- via the Secondary Air Injection (AIR) pump relay -2- . Air reaches the combination valves for Secondary Air Injection (AIR) -4- and -8-.
- The Secondary Air Injection (AIR) valve -5- is activated in parallel, which allows the vacuum to reach the combination valves for Secondary Air Injection (AIR) -4- and -8-. The appropriate combination valve for Secondary Air Injection (AIR) thereby opens the path for secondary air to the exhaust channels of the cylinder head.