6 Series E64 650i (N62TU) CONVER
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 unfavourable 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 petrol (minimum RM 91) possible. The knock control provides:
•
Protection from damage caused by knock (also in unfavourable 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.
SBT 8-cylinder spark-ignition engine N62TU E60, E61, E63, E64, E65, E66, E70
BMW AG - TIS
06.02.2013 10:29
Issue status (12/2007) Valid only until next DVD is issued
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