Brief description of components

The engine control system of the V8 engine is described for the E65.

With the digital engine electronics (DME) on the N62TU, the following sensors supply signals to the DME control unit:

• 2 eccentric shafts 

  The eccentric shaft sensor records the position of the eccentric shaft for the Valvetronic. The eccentric shaft adjusts the camshaft so that the optimum valve lift for the inlet valve is achieved regardless of operating condition (infinitely adjustable valve lift at intake).

  The eccentric shaft is adjusted by the Valvetronic actuator. The eccentric shaft sensor is equipped with 2 angle sensors which operate independently of one another. For safety reasons, 2 angle sensors are used with opposed maps. Both signals are digitally transmitted to the Valvetronic control unit.

• 2 inlet camshaft sensors and 2 exhaust camshaft sensors 

  The valve gear is equipped with variable camshaft control (double VANOS) for the inlet and exhaust camshaft. The 4 camshaft sensors record camshaft adjustment. To this end, a camshaft sensor gear is fixed to the camshaft. The camshaft sensor works according to the Hall effect. The integrated supply module supplies voltage to the camshaft sensors.

  • E70

  Power supply from front power distributor in junction box

• Accelerator pedal module 

  The accelerator pedal module identifies the position of the accelerator pedal.

  Using this information, the DME control unit calculates the required position of the Valvetronic or the throttle valve while taking other criteria into account. The accelerator pedal module is equipped with 2 independent Hall sensors.

  These Hall sensors each emit a voltage signal corresponding to the current accelerator pedal position. For safety reasons, two Hall sensors are used. The two Hall sensors supply a signal proportional to the position of the accelerator pedal.

  The 2nd Hall sensor always generates exactly half the voltage signal of the 1st Hall sensor. The two signal voltages are permanently monitored by the DME.

  The accelerator pedal module receives a constant voltage of 5 volts from the DME. For safety reasons, each Hall sensor has its own power supply from the DME.

• Hot-film air-mass sensor with intake air temperature sensor 

  The hot-film air-mass sensor records the air-mass which is drawn in. The DME control unit calculates the charge state using this information (base value for fuel injection period).

  A heated area on the hot-film air-mass sensor in the intake air flow is regulated to a constant excess temperature to the intake air. The intake air flow cools the heated area. This causes the resistance to change.

  The heater current needed to maintain the excess temperature is the measured variable for the intake air-mass. The new hot-film air-mass sensor (HFM 6) now works digitally. The electronic evaluation unit in the hot-film air-mass sensor digitalizes the sensor signal.

  The hot-film air-mass sensor supplies a pulse-width-modulated signal to the DME.

  The integrated supply module provides the power supply to the hot-film air-mass sensor.

  • E70

  Power supply from front power distributor in junction box

  There is also an intake air temperature sensor in the hot-film air-mass sensor housing. The intake air temperature sensor is a resistance with negative temperature coefficient (NTC).

  The intake-air temperature is input into a great many DME functions, e.g.:

  • Ignition timing calculation
  • Knock control adaptation
  • Idle speed control
  • VANOS actuation
  • Valvetronic actuation
  • Electric fan actuation

  A fault in the intake air temperature sensor will cause an entry to be stored in the DME fault memory. A substitute value is then used for engine operation.

• Crankshaft sensor 

  The crankshaft sensor records the position of the crankshaft with the aid of an increment gear screwed to the crankshaft. The crankshaft sensor is required in order to achieve fully sequential fuel injection (individual fuel injection for each cylinder at optimum firing point). The crankshaft sensor works according to the Hall effect.

  The circumference of the increment gear is divided into 60 equal teeth. The crankshaft sensor generates signal pulses. These signal pulses become shorter as the engine speed increases. The precise position of the pistons must be known for the fuel injection and the ignition to be synchronized. The increment gear has a gap of 2 teeth for this purpose.

  The number of teeth between the two gaps is permanently monitored. The signals from the camshaft sensors are compared to that from the crankshaft sensor. The signals must be within specified limits.

  If the crankshaft sensor fails, a substitute value is generated from the camshaft sensor signal (for engine starting and running).

  The integrated supply module supplies voltage to the crankshaft sensor.

  • E70

  Power supply from front power distributor in junction box

• Coolant temperature sensor 

  The coolant temperature sensor records the coolant temperature in the engine cooling circuit.

  The coolant temperature is the measured variable used in these calculations, for example:

  • Injection quantity
  • Nominal idle speed
• Temperature sensor on radiator outlet 

  The temperature sensor on the radiator outlet records the coolant temperature downstream of the radiator.

  The DME control unit requires information on the coolant temperature at the radiator outlet, e.g. to actuate the electric fan.

• Inlet pipe pressure sensor 

  On engines with Valvetronic, no vacuum is generated in the intake manifold in unthrottled operation. However, a vacuum is needed for certain functions, e.g. fuel tank ventilation or brake booster. For this reason, the electric throttle-valve actuator is closed as far as necessary to generate the required vacuum.

  The inlet pipe pressure sensor measures low pressure in the intake manifold.

  In engines with Valvetronic, for example, a partial vacuum of approximately 50 millibars is set in idle speed. Together with other signals, the inlet pipe vacuum serves as a substitute value for the load signal.

• 4 knock sensors 

  The 4 knock sensors detect combustion knock.

  The piezoelectric knock sensors record structure-borne sound in the individual cylinders. The DME control unit evaluates the converted voltage signals for each cylinder separately. The DME does this using a special evaluation circuit. Each knock sensor monitors 2 cylinders. Two knock sensors are packages as a single component.

• 4 oxygen sensors 

  For each cylinder bank, there is one oxygen sensor upstream of the catalytic converter and one oxygen sensor downstream of the catalytic converter.

  The oxygen sensors upstream of the catalytic converter are permanent sensors (LSU 4.9 control sensors).

  The oxygen sensors downstream of the catalytic converter are the familiar jump sensors (jump-like voltage changes at Lambda = 1).

  These oxygen sensors are the control sensors.

  The oxygen sensors are heated by the DME control unit so that they reach their operating temperature more quickly.

• Brake light switch 

  Two switches are fitted in the brake light switch: The brake-light switch and the brake light test switch (duplicated as a safety measure). The signals enable the DME control unit to determine whether or not the brake pedal is depressed.

  The Car Access System (CAS) provides the terminal R supply for the brake light switch via the light module (LM).

  • E70

  Power supply direct from CAS.

• Clutch module 

  The DME control unit uses the clutch switch signal in coupling mode to recognize whether the clutch pedal is depressed (manual transmission).

  This signal is important for the internal torque monitoring. Coasting mode, for example, is not possible when the clutch is depressed.

• Oil condition sensor 

  The oil condition sensor increases the function range of the thermal oil level sensor.

  The oil condition sensor measures the following ratings:

  • Engine oil temperature
  • Oil level
  • Engine oil quality

  The oil condition sensor sends the recorded measurement values to the DME.

  A bit-serial interface is used to transmit the signal to the DME.

  The integrated supply module supplies voltage to the oil condition sensor.

• Oil pressure switch 

  The oil pressure switch provides the DME control unit with an indication of whether or not there is sufficient oil pressure in the engine.

  The oil pressure switch is connected to the integrated supply module. The signal is fed through the integrated supply module to the DME.

  • E70

  The oil pressure switch is directly connected to the DME control unit.

  The signal from the oil pressure switch is checked for plausibility in the DME.

  To do this, the signal from the oil pressure switch is observed after the engine has been switched off.

  After a certain time, the oil pressure switch should not detect any more oil pressure. Is oil pressure is detected, the DME responds by recording a fault memory entry.

The following control units and other interfaces are involved in the digital engine electronics (DME):

• DME control unit 

  3 additional sensors are located on the board in the DME control unit:

  • Temperature sensor
  • Ambient-pressure sensor
  • New: Voltage sensor

  The thermal monitoring of components in the DME control unit is carried out by the temperature sensor.

  The ambient pressure is required to calculate the mixture composition. The ambient pressure reduces as the height above sea level increases.

  The voltage sensor on the DME control unit board monitors the power supply using terminal 87.

  The DME control unit is connected to the vehicle electrical system by 5 connectors.

  The DME control unit is linked to the safety and gateway module (SGM) and to the rest of the bus system by means of the powertrain CAN.

  • E60, E61, E63, E64 from 09/2005

  The body gateway module (KGM) is the gateway between the PT-CAN and the rest of the bus system.

  • E70

  The junction box electronics (JBE) is the gateway between the PT-CAN and the rest of the bus system.

• Valvetronic control unit 

  The 8-cylinder spark-ignition engine has its own Valvetronic control unit.

  Communication between the DME control unit and the Valvetronic control unit takes place via a separate local CAN (local, two-wire CAN bus).

  The DME activates the Valvetronic control unit via a separate wire. The DME control unit calculates all values needed to actuate the Valvetronic. The Valvetronic control unit evaluates the signals from the two eccentric shaft sensors. The Valvetronic control unit actuates the Valvetronic actuator motor to adjust the eccentric shaft.

  The Valvetronic control unit receives its power supply via the Valvetronic relay in the integrated supply module.

  • E70

  The Valvetronic control unit receives its power supply from the front power distributor in junction box.

  The Valvetronic control unit continuously checks whether the actual position of the eccentric shaft corresponds with its nominal position. This makes it possible to detect any stiff movements in the mechanics. In the event of a fault, the valves are opened as wide as possible. The air supply is then controlled by the throttle valve.

• Integrated supply module 
  • N62TU in the E70

  The E70 does not have an integrated supply module.

  • N62TU

  The 8-cylinder spark-ignition engine has an integrated supply module. The integrated supply module includes various fuses and relays (not a control unit, just a distributor). The integrated supply module acts as the central interface between the vehicle wiring harness and the engine wiring harness.

  The PT-CAN is also routed through the integrated supply module.

• CAS control unit 

  The electronic immobilizer is integrated into the CAS control unit as an anti-theft system.

  The engine can only be started if the electronic immobilizer enables this.

  Moreover, the CAS control unit provides the powertrain CAN wake-up signal (terminal 15 wake-up) to the DME.

  The CAS control unit switches the starter motor on (convenient-start system).

  • E65, E66

  The DME switches the starter motor on.

• Alternator 

  The alternator exchanges data with the DME control unit using a bit-serial data interface. The alternator sends the DME control unit information on type and manufacturer, for example. This enables the DME control unit to modify the alternator control to suit the alternator model which has been installed.

• DSC control unit 

  The DSC control unit sends the signal containing information on the vehicle's road speed via a separate line (redundant to PT-CAN) to the DME control unit. The signal is needed for various functions, e.g. for the cruise-control system and speed limiter.

• Instrument cluster 

  The outside temperature sensor sends its signal to the instrument cluster.

  The instrument cluster forwards the signal through the bus to the DME.

  The outside temperature is needed for a number of functions in the control unit that include temperature-dependent values.

  In the event of a fault in the outside temperature sensor, the DME control unit reacts with an entry in the fault memory. The DME calculates a substitute value from the intake-air temperature.

  The instrument cluster switches the DME indicator and warning lights on, e.g. the emissions warning light. The instrument cluster displays any Check-Control messages present.

  The fuel level sensor is also connected to the instrument cluster. The instrument cluster emits the signal from the level sensor as a message on the CAN. The DME needs this CAN message about the fuel level so that it can deactivate misfiring detection when the fuel level is low and to enable the DMTL (DMTL = "diagnosis module for tank leak").

• A/C compressor 

  The DME control unit is connected to the integrated automatic heating/air conditioning system (IHKA) through the bus system. The IHKA switches the A/C compressor on or off.

  The DME control unit supplies the signal to the IHKA through the bus.

• Active Steering, Active Cruise Control, electronic transmission control 

  The DME control unit is connected by the bus system to the following control units (depending on the equipment fitted in the vehicle):

  • AL: Active Steering
  • ACC: Active Cruise Control
  • EGS: Electronic transmission control
  • LDM: Longitudinal dynamics management

  These interfaces are needed for the torque monitoring function.

The digital engine electronics (DME) activates the following actuators:

• 2 Valvetronic actuator motors via the Valvetronic control unit 

  The air flow to the engine during throttle-free operation is adjusted by the variable valve lift and not the throttle valve.

  Valvetronic is driven by an electric motor. The Valvetronic actuator is mounted on the cylinder head. The Valvetronic actuator uses a worm gear to drive the eccentric shaft in the cylinder head oil chamber.

  The eccentric shaft sensor indicates the position of the eccentric shaft to the DME control unit via the Valvetronic control unit.

• 2 DISA servomotors for variable intake manifold 

  The N62TU has a 2-stage differentiated air intake system (DISA).

  The DISA servomotor drives 4 sliding sleeves for each cylinder bank.

  The sliding sleeves lengthen or shorten the intake port.

  This means that a more ample torque curve is reached at low engine speeds without a loss of engine output at higher engine speeds.

• Electric throttle-valve actuator 

  The DME control unit calculates the position of the throttle valve: from the position of the accelerator pedal and the torque required by other control units. In the electric throttle-valve actuator, the position of the throttle valve is monitored by 2 potentiometers.

  The electric throttle-valve actuator is electrically opened or closed by the DME control unit.

  With Valvetronic, the throttle-valve actuator is activated for the following functions:

  • Engine start (warm-up)
  • Idle speed control
  • Full load operation
  • Emergency operation
• 4 VANOS solenoid valves 

  The purpose of the variable camshaft control is to increase torque in the low and medium engine speed ranges.

  A VANOS solenoid valve controls a VANOS adjustment unit on the intake end and the exhaust end.

  The VANOS solenoid valves are controlled by the DME control unit.

• Electric fuel pump 
  • E65, E66

  The right-hand B-pillar satellite actuates the electric fuel pump as required.

  The following control units are involved in controlling the fuel pump:

  • DME: Detection of the current fuel consumption in the engine on the basis of the required injection quantity
  • SGM (safety and gateway module): Signal transfer
  • SBSR (B-pillar satellite, right): Fuel pump regulation and emergency fuel cutoff
  • E60, E61, E63, E64 and E70

  The DME control unit monitors the activation of the fuel pump relay. The fuel pump relay is controlled via a safety circuit only when the engine is running and shortly after terminal 15 ON for pressure build-up (delivery line for fuel pump).

• 8 injectors 

  During fully sequential fuel injection, each injector is controlled by the DME control unit via its own final stage.

  Here, the injection timing for the cylinder concerned is adjusted to the operating conditions (engine speed, load and engine temperature).

  The integrated supply module provides the power supply for the injectors.

• Fuel evaporation control valve 

  The fuel evaporation control valve regenerates the activated carbon filter using scavenging air. The scavenging air which is drawn through the activated carbon filter is then enriched with hydrocarbons and fed to the combustion engine.

  In a current-free state, the fuel evaporation control valve is closed. This prevents the ingress of fuel vapor from the activated carbon filter into the inlet pipe when the engine is switched off.

  The integrated supply module supplies voltage to the fuel evaporation control valve.

  • E70

  The rear power distributor supplies power to the fuel evaporation control valve.

• 8 ignition coils with overload-protection relay 

  The ignition coils are activated by the DME control unit. The ignition coils receive their power supply from the overload-protection relay in the integrated supply module.

  • E70

  No integrated supply module; the relief relay is fitted separately.

• Mapped thermostat 

  The opening and closing of the mapped thermostat is controlled by a characteristic map.

  The mapped thermostat ensures that within its control range a constant coolant temperature is maintained at the engine inlet.

  For driving conditions with low loads, the mapped thermostat sets a high coolant temperature (efficient consumption).

  For full loads or higher engine speeds, the coolant temperature is reduced to protect the components.

  The integrated supply module supplies voltage to the mapped thermostat.

  • E70

  The mapped thermostat receives its power supply from the front power distributor in junction box.

• Electric fan 

  The electric fan is controlled by the DME control unit via a pulse-width-modulated signal (evaluation by electronic circuitry in the fan).

  The DME control unit controls the various electric fan speeds by means of a pulse-width-modulated signal (between 10 and 90 %).

  Cycle ratios which are less than 5 % and greater than 95 % will not trigger the control device and are used for the purposes of fault recognition.

  The speed of the electric fan is dependent on the coolant temperature at the coolant outlet (radiator) and the pressure in the air-conditioning system. When the car's road speed increases, the speed of the electric fan decreases.

• Electronics box fan 

  Extremely high temperatures are encountered in the electronics box.

  These are caused by the heating from the engine compartment and the power loss from the control units in the electronics box. The electronics box fan is installed because control units can only be operated in a certain temperature range.

  The maximum permissible operating temperatures must not be exceeded. The expected service life of electronic components increases with decreasing temperature.

• Exhaust flap 
  • E70

  The E70 has no exhaust flap.

  A diaphragm canister is fixed onto the right-hand rear silencer exhaust pipe. The diaphragm canister is linked to the exhaust flap via an adjustment mechanism.

  The vacuum hose goes from the solenoid valve to the diaphragm can.

  The exhaust flap reduces the noise level when the engine is idle and when the engine speed is close to idle.

  The exhaust flap is closed at low engine speeds and when the engine is not running. At higher engine speeds, the exhaust flap opens.

  The DME controls the solenoid valve for the exhaust flaps. The adjacent partial vacuum opens the exhaust flap. The degree of opening depends on engine load and engine speed.

  • E65, E66

  When the engine is switched off, the diaphragm can is ventilated via a restrictor. This allows the exhaust flap to execute a damped closing. The cutoff valve is actuated by the power module (PM).