M5.2.1 - Overview - 5-Series, 7-Series: M5.2.1: Operation

Operation of the system begins on cold engine start up. The ECMs provide a ground path to open the valves allowing additional metered air to be drawn into the fuel injectors to the manifold.

If the vehicle is stationary and idling, this process continues until the engine coolant temperature reaches 75°C. If the vehicle is started and driven, the additional air is injected through the warm up phase of the engine. The ECM then releases the ground path so the valves spring closed.

Fig 1: Identifying Air Containment Valve

NOTE: Air injection will be interrupted during idle at engine operating temperature, if the idle speed becomes too high!

Similar to the M62, a brake booster is linked into the system by the vacuum amplifier. On the M73 this requires an equal "balance" of vacuum bleed on the opposite bank allowing equal DK motor synchronization. This system has fault recognition and is diagnosable using the DIS.

Fig 2: Identifying Air Containment Valve Plumbing Schematic