Air Injection: Description and Operation

2665 Secondary air injection

Secondary air injection is activated by the Motronic control module. The air supplied by the secondary air injection opens the check valve through excess pressure, the air is then blown through the lines to behind the exhaust valves of the respective cylinder heads.







The injection of secondary air leads to a reduction of the CO and HC pollutants that are increasingly created by operating with Lambda < 1 when running cold.
Additionally, the catalytic converters achieve their activation temperature of approx. 350 °C more quickly due to the waste heat created during the afterburning. Activation conditions are achieved during the first cold start process if the coolant temperature is between -10 °C and +42 °C. When running close to idle speed, secondary air injection is active for approx. 60 seconds, for a partial load up to 80 seconds. If during secondary air injection an intake air mass of approx. 332 kg is exceeded, the secondary air injection is deactivated.







NOTE: Diagnosis: The secondary air system's functions are monitored by the oxygen sensor control. The secondary air blower is monitored by the output module diagnosis system.