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:
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.
The 4 camshaft sensors record camshaft adjustment. 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
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
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 airmass.
The new hot-film air-mass sensor (HFM 6) now works digitally. The electronic evaluation unit in the hot-film airmass 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.
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
The coolant temperature is the measured variable used in these calculations, for example:
The DME control unit requires information on the coolant temperature at the radiator outlet, e.g. to actuate the electric fan.
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.
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.
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).
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.
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.
This signal is important for the internal torque monitoring. Coasting mode, for example, is not possible when the clutch is depressed.
The oil condition sensor measures the following ratings:
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.
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):
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.
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.
> 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.
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.
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").
The DME control unit supplies the signal to the IHKA through the bus.
These interfaces are needed for the torque monitoring function.
The digital engine electronics (DME) activates the following actuators:
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.
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.
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:
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.
The following control units are involved in controlling the fuel pump:
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).
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.
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.
> E70
No integrated supply module; the relief relay is fitted separately.
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.
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.
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
> 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).