DME/MOTRONIC Control Unit: Notes

A 55-pin DME/Motronic control unit is used in 535i, 735i and 735iL. An 88-pin control unit is used on all other models. See DME/MOTRONIC CONTROL UNIT LOCATION  table. The control unit uses input signals from the following engine sensors to determine optimum fuel injection and ignition timing: intake airflow, intake air temperature, throttle position, coolant temperature, engine speed, vehicle speed, crankshaft position and exhaust gas oxygen content.

The DME/Motronic control unit can operate engine in a "limp mode," allowing vehicle operation despite component failure. The DME/Motronic control unit also has adaptive capabilities to compensate for component wear and other factors, such as minor air (vacuum) leaks. Once a fault is recognized, it is stored in DME/Motronic control unit memory as a fault code. The system automatically substitutes a fixed replacement value for the incorrect value caused by a defective component or circuit.

An air/fuel ratio of 14.7:1 is maintained under most driving conditions. Maximum engine RPM is limited by the DME/Motronic control unit by eliminating power to fuel injectors. The DME/Motronic control unit assumes control of the following functions.