DME/MOTRONIC Control Unit

A 55-pin DME/Motronic control unit is used on 535i. See DME/MOTRONIC CONTROL UNIT LOCATION table. The control unit uses the following input signals 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, Fuel Injection Control, Ignition Timing Control, Cold Start Control, Idle Speed Control, Kickdown Prevention, Oxygen (Sensor) Control, Fuel Tank Vent (Evaporation) Control, Relay Controls and Self-Diagnostics..