For the Quantity Mean Value Adaptation function, a Lambda oxygen sensor is required in all EU4 diesel engines. This sensor is fitted near the engine in the pre-catalytic converter, immediately after the turbine of the exhaust turbocharger. The oxygen sensor is a wide-band sensor that provides exact lambda values over a wide measuring range. The quantity mean value adaptation is a learning procedure in which the fuel-air ratio (oxygen sensor value) is correctly adjusted by adapting the air mass or exhaust gas recirculation rate. This procedure does not affect the individual injectors.
Important: On the M67TÜ, two oxygen sensors are fitted; their signals are evaluated individually by the DDE control units master and slave. What is described below applies to both of the oxygen sensors. Oxygen sensor 1 is located in the direction of travel on the right.
The oxygen sensor value measured by the Lambda oxygen sensor and the air mass measured by the HFM are used to determine a mean injection quantity across all cylinders. This value is compared with the injection quantity specified by the DDE control unit. If there is a deviation, the air mass is adapted to the actual amount of fuel by adjusting the exhaust gas recirculation valve in such a way that the correct lambda value is set.
The MMA is not a rapid control operation, rather an adaptive learning procedure. That means that the error in injection quantity is learned in an adaptive characteristic map that is stored permanently in the DDE control unit.
The Reset MMA service function must be run if any of the following components has been replaced:
The Quantity Mean Value Adaptation function is required to achieve the exhaust emission regulation EU4. This exhaust emission regulation came into force in the years 2005. The MMA is deployed as follows: