Part 3

11 03 05 (142)
8-cylinder spark-ignition engine N62TU
E60, E61, E63, E64, E65, E66, E70

Continued from part 2

System functions
The following system functions are described:
In part 2 (refer to part 2)

- Power management
- Electronic immobilizer
- Comfort start
- Air supply: 2-stage differentiated air intake system "DISA"
- Charge monitoring
- "Valvetronic" variable valve gear
- "VANOS" variable camshaft control

In part 3 (below)

- Fuel supply system
- Fuel injection
- Ignition-circuit monitoring
- Alternator actuation
- Oil supply
- Engine cooling
- Knock control
- Tank ventilation
- Lambda control system
- Torque monitoring
- Evaluation of road speed signal
- A/C compressor actuation
- Intelligent alternator regulation
- Active air flap control


Fuel supply system
> E65, E66
The fuel supply system on the BMW 7-Series is requirement-orientated and thus depends on consumption.
The DME calculates the amount of fuel required on the basis of various operating variables.
In turn, the engine's current fuel requirement is calculated from this value. The DME requests this value as a volumetric flow with the unit "liters per hour".
The DME sends this request on the following path: DME (digital engine electronics -> PT-CAN -> SGM (safety and gateway module) -> byteflight -> SBSR (B-pillar satellite, right) -> EKP (regulated fuel pump).
The B-pillar satellite, right converts the amount of fuel requested into a nominal speed for the fuel pump.
The pump speed is regulated via the cycle ratio of a pulse-width-modulated signal. This rectangular signal gives the effective supply voltage for the fuel pump: The longer the pause between the edges of the rectangular signal, the lower the supply voltage for the fuel pump. The fuel pump delivery volume is correspondingly lower. The fuel pump speed is sent back to the B-pillar satellite, right as an input variable.

This method has the following benefits compared to the conventional way of actuating the fuel pump (fuel-pump relay):
- Lower current draw from fuel pump
- Reduced heating up of fuel
- Longer service life for fuel pump
- No fuel-pump relay needed
The flow of fuel is interrupted in the event of a crash of sufficient impact. This prevents the fuel from escaping or igniting (emergency fuel cutoff).
The fuel pump can be reactivated by switching the ignition off and on again.
If the request signal from the DME or the pulse-width-modulated signal from the SBSR is not received: The fuel pump will operate a maximum delivery capacity. This guarantees sufficient fuel supply for all operating conditions (emergency operation).
> E60, E61, E63, E64 and E70
The DME switches the fuel pump on using the fuel-pump relay.



Fuel injection
During fully sequential fuel injection, each injector is controlled by means of its own final stage.
Fully sequential fuel injection has the following advantages:
- Improved fuel preparation for each individual cylinder
- Adaptation of the fuel injection timing to suit the engine's operating condition (engine speed, load, engine temperature)
- Cylinder-selective correction of injected fuel quantity for varying load (during a cycle, the fuel injection timing can be corrected by extending or shortening it)
- Cylinder-selective cutoff (e.g. when an ignition coil is defective)
- Diagnosis for each individual injector possible
The control of each injector by means of its own individual final stage achieves a fuel build-up which is the same in all cylinders. This ensures a uniformly-effective fuel preparation throughout.
The fuel build-up time is variable and depends on the load, engine speed and engine temperature.
As it is only injected once per camshaft rotation, the spread of fuel due to tolerances in the components is reduced.
In addition, the idle-running performance is improved as the response and dropout times at the injectors are reduced.
Moreover, a marginal reduction in fuel consumption is also achieved.

When the vehicle is in motion and there is a sudden acceleration or the throttle is closed, the fuel injection period can be adjusted. If the injectors are still open, the mixture at every valve can be adjusted by extending or shortening the fuel injection period. This achieves an improved engine response.



Ignition-circuit monitoring
The current in the primary coil for the ignition coil is used to monitor the ignition circuit. When the engine is switched on, the current must stay within specific values during certain time thresholds.
The ignition diagnosis monitors the:
- Primary power circuit for the ignition coil
- Ignition wiring harness
- Secondary power circuit for the ignition coil with the spark plug
The ignition-circuit monitoring can detect the following faults:
- Short circuit at the primary end of the ignition coil
- Short circuit at the secondary end of the ignition coil
- Defective spark plug
- Break in wire to actuator
- Defective ignition output stage
The following are not detected:
- Intermittent faults such as loose contacts in the wire to the actuator
- Spark-over in high-tension circuit parallel to spark gab where a short-circuit in the coil does not develop



Alternator actuation (bit-serial data interface)
The following functions have been implemented in the DME control unit for the alternator with bit-serial data interface (BSD):
- Switching the alternator on and off using defined parameters
- Specification of the alternator's maximum permissible power consumption
- Calculation of the input torque for the alternator based on the power consumption
- Control of the alternator's response when higher electrical loads are connected (load-response function)
- Diagnosis for the data line between the alternator and DME control unit
- Storage of faults which develop in the alternator in the fault memory of the DME control unit
- Actuation of the charge-current indicator light in the instrument cluster via bus connection
- Introduction of intelligent alternator regulation:
> from 03/07 in the E60, E61
> from 09/07 in the E63, E64, E70
The principal function of the alternator is also guaranteed when communication between the alternator and DME control unit is interrupted.

The following fault causes can be distinguished in fault memory entries:
- Overheating protection:
The alternator is overloaded. For safety reasons, the alternator voltage is reduced until the alternator has cooled down (charge telltale light does not light up).
- Mechanical fault:
There is a mechanical block in the alternator. or: The belt drive is defective.
- Electrical fault:
Excitation diode defective, excitation coil has been interrupted, overvoltage due to defective governor.
- Communication failure:
Line between DME control unit and alternator defective.
An interruption or short circuit in the alternator coils will not be detected.



Oil supply
The oil condition sensor reports the engine oil level and engine oil quality back to the DME control unit. A temperature sensor in the oil condition sensor indicates the engine oil temperature. The engine oil temperature is used together with the coolant temperature to calculate the engine temperature.
The oil pressure is indicated by the oil-pressure switch.
The oil level is also measured for the electronic oil level check. The 2nd capacitor in the upper part of the oil condition sensor registers the oil level. The capacitor is at the same level as the oil level in the oil sump.
As the oil level falls, the capacitance of the capacitor falls. The electronic evaluation unit creates a digital signal from this. The DME then calculates the engine oil level.
The DME control unit activates the warning and indicator lamp in the instrument cluster via the PT-CAN (red: oil pressure low; yellow: oil level low).
Electronic oil level check:
The dipstick now has a black handle. The engine oil level is measured by the oil condition sensor.
The measured value is displayed in the Central Information Display (CID).
The signal from the oil condition sensor is evaluated in the DME. Besides the oil level, the thermal oil level sensor also indicates the engine oil temperature.
Condition Based Service:
In addition, the engine oil quality is measured for the Condition Based Service (CBS).
The electrical material properties of the engine oil change as the engine oil wears and ages. The changed electrical properties of the engine oil (dielectrics) cause the capacity of the capacitor in the oil condition sensor to change.
The electronic evaluation unit converts the measured capacity into a digital signal.
The digital sensor signal is transmitted to the DME as a statement about the condition of the engine oil.
The DME uses this to calculate the next engine oil change as part of Condition Based Service (CBS).



Engine cooling
The opening and closing of the mapped thermostat is controlled by a characteristic map. This regulating operation can be split into 3 operating ranges:
- Mapped thermostat closed:
The coolant only flows through the engine and the coolant circuit is closed.
- Mapped thermostat open:
The entire coolant volume flows through the radiator. This results in maximum use of the available cooling output.
- Control range of the mapped thermostat:
A proportion of the coolant flows through the radiator. The mapped thermostat maintains a constant coolant temperature within the control range at the engine inlet.
In this operating range, the coolant temperature can now be selectively controlled with the assistance of the mapped thermostat. This means that a high coolant temperature can be set in the part-load range of the engine. High operating temperatures in the part-load range result in improved combustion. This in turn leads to reduced consumption and exhaust emissions.
During full load operation, certain disadvantages are associated with higher operating temperatures (retarding of ignition due to knock).
A lower coolant temperature is therefore specifically set during full load operation with the assistance of the mapped thermostat.



Knock control
The engine is equipped with a cylinder-selective adaptive knock control.
4 knock sensors detect combustion knock (cylinders 1 and 2, cylinders 3 and 4, cylinders 5 and 6, cylinders 7 and 8). The sensor signals are evaluated in the DME control unit.
If the engine is operated with combustion knock for longer periods of time, this can cause serious damage.
Knock is encouraged by:
- Increased compression ratio
- High cylinder fill levels
- Inferior fuel grade (RM/MM)
- High intake-air and engine temperature
The value of the compression ratio can also become too high due to spread due to deposits or the manufacturing process. On engines without knock control, these unfavorable influences must be taken into account. The design of the ignition system must include a safety gap to the anti-knock limit. This makes reduced efficiency in the upper load range unavoidable.
The knock control prevents knock. The firing point of the relevant cylinder (cylinder-selective) is set as far as possible in the retarded direction only when a knocking risk is present.
This means that the ignition control grid can be designed around ideal consumption values (without having to take the anti-knock limit into account). A safety margin is no longer necessary.
The knock control performs all the necessary corrections to the firing point due to knock and also makes trouble-free driving with regular grade gasoline (minimum RM 91) possible. The knock control provides:
- Protection from damage caused by knock (also in unfavorable conditions)
- Reduced consumption and increased torque throughout the entire upper load range (according to the quality of fuel used)
- High economic efficiency through optimum use of the available fuel quality and by taking the specific engine condition into account
The knock control self-diagnosis performs the following checks:
- Check for signal interference, e.g. breaks in wiring or defective connector
- Self-test for evaluating circuit
- Check of engine noise level recorded by the knock sensor
If a fault is identified during one of these checks, knock control is deactivated. An emergency program assumes control of the ignition angle. A fault is simultaneously registered in the fault memory. The emergency program guarantees damage-free operation from a minimum of RON 91. The emergency program depends on the load, engine speed and engine temperature.



Tank ventilation
The fuel evaporation control valve controls the regeneration of the activated carbon filter with scavenging air.
Scavenging air drawn through the activated carbon filter is enriched with hydrocarbons (HC) depending on the loading of the activated carbon. The scavenging air is subsequently fed to the engine for combustion.
The formation of hydrocarbons in the fuel tank is dependent on:
- Fuel temperature and ambient temperature
- Air pressure
- Fill level in the fuel tank
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.



Closed-loop Lambda control system
Optimum efficiency of the catalytic converter can only be achieved if an ideal fuel/air ratio is used for combustion (l = 1). To this end, oxygen sensors are used upstream and downstream of the catalytic converter.
The oxygen sensors upstream of the catalytic converter have a steady characteristic output curve (measure oxygen content in rich and lean ranges.)
The measurement method employed by this oxygen sensor is different to an oxygen sensor with an erratic characteristic output curve. The oxygen sensor is therefore connected using 6 pins instead of 4.

- Oxygen sensors upstream of catalytic converter
The oxygen sensors upstream of the catalytic converter (control sensors) are used to assess the composition of the exhaust gas.
The control sensors are screwed into the exhaust manifold.
The oxygen sensors measure the residual oxygen content in the exhaust fumes. The voltage values determined are relayed to the DME control unit. The DME control unit corrects the mixture composition by adjusting the injection period.
Values which are greater or less than l = 1 are aimed at depending on the operating condition.

- Oxygen sensors downstream of catalytic converter
The oxygen sensors downstream of the catalytic converter (monitoring sensors) are used to monitor the control sensors. In addition to this, the function of the catalytic converter is monitored.
To ensure full operational reliability of the oxygen sensors upstream of the catalytic converter, a temperature of approximately 750 °C is required (350 °C for oxygen sensors downstream of the catalytic converter). For this reason, all oxygen sensors are heated.
The oxygen sensor heating is controlled by the DME control unit. When the engine is cold, the oxygen sensor heating remains switched off, as condensation which is present would otherwise destroy a hot oxygen sensor due to thermal strain.
This means that the closed-loop Lambda control only becomes active a short time after the engine has started, once the catalytic converters have warmed up. The oxygen sensor is initially warmed up using a reduced heating power, to avoid imposing unnecessary loads on it due to thermal strain.



Torque monitoring
The DME monitors the torque required.
The following systems may request torque data from the DME control unit:
- Active Steering
- Servotronic
- Alternator
- Cruise control
- Dynamic Stability Control
- Transmission management
- Internal monitoring against "self-acceleration"



Evaluation of road speed signal
The road speed signal is required by the DME control unit in order to perform several functions:
- Speed limiting function:
Once the maximum road speed has been reached, the fuel injection and ignition are adjusted. If required, individual ignition and injection signals are suppressed. A "soft" speed limiting function is thus carried out.
- Control of A/C compressor:
When the air-conditioning system is switched on, the A/C compressor is switched off during full-load acceleration,
provided that: the car's road speed is less than 13 km/h.
- Idle speed control:
If the car's road speed is 0 km/h, the idle speed is adjusted (depends on A/C compressor ON, selected drive position for automatic transmission, light ON).
- Poor-road-surface detection:
At low road speeds, the check for smooth engine operation is switched off.



A/C compressor activation
The DME control unit supplies the signal to actuate the A/C compressor.
The A/C compressor is switched off under the following conditions:
- Full engine load
- car's road speed under 13 km/h
- Engine overheating
The IHKA actuates the A/C compressor. The DME sends the signal on the bus system.



Intelligent alternator regulation
Intelligent alternator regulation systematically controls the battery charge state.
The battery is predominantly charged in overrun mode.
Depending on the battery charge state, the battery will not be charged during an acceleration phase.



Active air flap control
Active air flap control regulates the air supply for the engine and assemblies cooling system by only opening the air flaps as they are needed.

Notes for service staff
The following information is available for service staff:

- General note:
- Diagnosis:
- Encoding/programming: ---

US national version
Fuel tank leakage diagnosis module

The fuel system leak test is regularly conducted when the engine is switched off. Here, the following processes are executed during the DME run-down period:
- Initial situation
During normal engine operation, the switchover valve in the diagnosis module is in the "Regeneration" position. Fuel vapors are stored in the activated charcoal filter and fed into the engine depending on the actuation of the fuel evaporation control valve (please refer to "Fuel tank ventilation").
- Starting conditions check
After the engine is switched off, the conditions necessary to restart are checked:
- Engine off
- Battery voltage between 11.5 and 14.5 volts
- No fault memory entry in the DME regarding diagnosis module for tank leak or tank-ventilation system
- Fuel level greater than 10 % and less than 90 %
If the result is positive, tank leakage diagnosis is started with a comparison measurement.
- Comparison measurement
The fuel evaporation control valve is always closed when the engine is switched off. The switchover valve in the diagnosis module remains in the "Regeneration" position. The electric leakage diagnosis pump impels fresh air from the surrounding area through a defined leak of 0.5 mm diameter. The current draw needed for this is stored as a value. The actual tank leakage diagnosis then follows.
- Tank leakage diagnosis:
The fuel evaporation control valve remains closed. The switchover valve in the diagnosis module is switched to the "Diagnosis" position. The leakage diagnosis pump impels fresh air from the surrounding area into the tank, causing the interior pressure to slowly increase. At the start of tank leakage diagnosis, the interior pressure is equal to the ambient pressure. The current draw is therefore low. As the pressure inside the tank increases, the current draw also increases. The DME evaluates the current draw of the leakage diagnosis pump.
- Pump current evaluation
The DME evaluates the increase in the current draw over a certain time.
If the current draw exceeds the value stored within this time, the fuel system is considered to be OK. Tank leakage diagnosis is ended.
If the current draw does not reach the value stored, the fuel system is considered to be defective.
Tank leakage diagnosis allows a difference to be made between:
- Major leak, e.g. fuel cap missing
- Minor leak
- Micro-leak
The relevant fault is entered in the DME fault memory. Tank leakage diagnosis is then ended.
- End of tank leakage diagnosis:
The switchover valve is switched back to the "Regeneration" position. The DME run-down period remains available for other functions.
Tank leakage diagnosis can also be started with the BMW diagnosis system. In this case, the processes run as described above.
Subject to change.