System Overview
DME And EML Diagram:
PURPOSE
The Digital Motor Electronic system (DME) 1.7, provide precise control of fuel injection and ignition systems to ensure optimum performance and strict emission compliance.
OPERATION
The BMW V12 engine uses two Motronic (DME) engine control systems. DME control unit 1 controls cylinders 1-6, and DME control unit 2, cylinders 7-12. Each Motronic system is complete and independent of its counterpart, except for the Oxygen Sensor Heating Relay and Coolant Temp. Sensor, and is capable of running the engine on 6 cylinders in the event of a system failure. An electronic throttle control system (EML), controls throttle operation and coordinates the separate DME systems. Various engine sensors and other systems (i.e.. air conditioning, auto transmission etc.) supply each DME control unit with operating information. The DME control units process this information and send control signals to adjust injector pulse width, ignition timing and other important systems and components.
Inputs signals include:
Components: Information:
Digital motor electronics Voltage supply for a part of the digital
DME main relay motor electronics
Pulse generator, engine Engine speed and
speed/position I and II crankshaft position
Pulse generator, cylinder Feedback of injection signal of defined
reference point I and II cylinder
Intake temperature sensor Temperature of intake air (in this way,
I and II the air density which is reduced as the temperature increases is taken into consideration)
Engine temperature sensor I Temperature of engine coolant
and II (in one housing)
Mass Air Sensor I and Quantity or mass of air drawn in
II
Oxygen sensor I and II Oxygen content of exhaust gas
Idle-CO potentiometer I and II Variable resistor (varistor)
(without catalytic converter) for setting the CO content while idling
Instrument cluster Vehicle speed signal
Air conditioning, defroster or Air conditioning in operation
air recirculation switch
A/C compressor A/C compressor in operation
Battery Current system voltage
Terminal 15 Ignition switched on
On-board computer (BC) Code entered
(engine operation not possible)
Antitheft system (DWA) DWA Antitheft system armed
(engine operation not possible)
Electro throttle control (EML) Idle and lull load signal
Electronic transmission con- Shift procedures active,
trol (EGS) torque converter clutch engaged
Range selector lever for elec- Engaged gear range
tronic transmission control
Automatic stability control Signal for retarding ignition timing and
(ASC) signal for blanking out ignition and injection
Engine drag torque control Signal for suppressing deceleration
(MSR) fuel cut-out during engine drag torque control
Output Signals include:
Components Information
Injector valves Injection time
Ignition coil I and II Ignition voltage
Fuel evaporation control valve Clock pulses for operating cycles
I and II
Digital motor electronics DME Voltage supply
main relay I and II
A/C compressor relay Switching off A/C compressor
Electrical fuel pump relay Activation voltage
and II
Oxygen sensor heating relay Activation voltage
Instrument cluster Engine speed signal, injection signal (for fuel consumption indicator), fault lamp (US only)
Electronic transmission con- Engine speed signal, engine tempera
trol EGS ture, throttle angle
Electronic throttle control EML Injection signal
Automatic stability control Engine speed signal
ASC
Air mass meter I and II Burn-clear
The DME system assumes functions listed below:
^ Injection control
^ Ignition liming control
^ Cold start control
^ Engine speed control
^ Acceleration enrichment
^ Dynamic torque deceleration fuel cut~out
^ Catalytic converter protection function (ignition circuit monitoring)
^ Adaptive emission (lambda) control
^ Adaptive fuel evaporation control
^ Intervention in ignition and injection with ASC or MSR active
^ Characteristic map switchover for EH transmission
^ Relay control
^ A/C compressor cut-out
^ Self-diagnosis with defect code storage
The system can also operate in conjunction with other systems such as:
^ Electronic transmission control EGS
^ Electronic throttle control EML
^ Automatic stability control ASC
^ Engine drag torque control MSR
^ Instrument cluster
^ Antitheft system DWA
^ On-board computer BC