Secondary Air Injection

1996 emission regulations require that the M52 engine is to be equipped with a secondary air injection system. Control and monitoring of the air injection system is a function of the MS41.1 control module.

The components of the system include:
- Secondary Air Injection Electric Motor/Pump
- Electric Motor/Pump Relay
- Vacuum vent valve (solenoid)
- Non-return valve
- Secondary air injection pipes

The use of a secondary air injection system for cold starting/warm up helps reduce the warm up time of the catalyst and reduces HC and CO emissions.





SECONDARY AIR INJECTION CONTROL
Secondary air injection is provided1 by the MS 41.1 Control Module, through the air injection motor/pump relay and the Vacuum Vent Valve.

The parameters for air injection operation are shown in the chart.

If the engine is within the specified temperature range on start up, the air injection system is switched on for two minutes.

SECONDARY AIR INJECTION MONITORING
Component operation of the air injection pump and vacuum vent valve are monitored by the MS41.1 control module at the final stage control. The control module checks the system for correct operation.

The MS41.1 control module carries out a functional check of the air injection system every time the engine is started, as long as the operating criteria for checking are satisfied. Operation of the air injection system is verified from the feedback signals of the oxygen sensors.