1 Series E87 118i (N46) 5-door
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Full load operation
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Emergency operation
In all other operating conditions, the throttle valve only remains open far enough to induce a slight low pressure.
This low pressure is required to ventilate the tank, for example.
The DME control unit calculates the associated setting of Valvetronic using the position of the accelerator pedal
and other variables.
The DME control unit controls the Valvetronic actuator 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 records the current position of the eccentric shaft. The eccentric shaft sensor is
equipped with 2 angle sensors.
The DME control unit adjusts the current position of the eccentric shaft via the Valvetronic actuator until the
nominal position is reached.
For safety reasons, 2 angle sensors are used with characteristic curves which have opposing directions. Both
signals are digitally transmitted to the DME control unit. The DME control unit supplies 5 volts to both angle
sensors.
Both signals from the eccentric shaft sensors are continuously monitored by the DME control unit.
Checks are made as to whether the signals are plausible in their own right and also in relation to one another.
The signals may not differ. Where a short circuit or fault develops, the signals lie outside the measuring range.
The DME 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 controlled by the throttle
valve. If the actual position of the eccentric shaft cannot be detected, the valves are opened to the maximum
extent without regulation (controlled emergency operation).
In order to achieve the correct valve opening, an adaptation must be made to balance all tolerances in the valve
gear. During this adaptation process, the mechanical stops on the eccentric shaft are adjusted.
The positions registered are subsequently saved. These positions are used as the basis for calculating the
actual valve lift at any point during operation.
The adaptation process is automatic: Each time the engine is restarted, the position of the eccentric shaft is
compared with the values registered. If following a repair, for example, a different position of the eccentric shaft
is detected, the adaptation process is carried out. In addition, the adaptation can be initiated via the BMW
diagnosis system.
"VANOS" variable camshaft control
The variable camshaft control improves torque in the low and medium engine speed range.
Due to a larger valve overlap, the volume of residual fumes at idle speed is reduced. A recirculation of internal
exhaust gas in the part-load range reduces the volume of nitrogen oxide.
The following is also achieved:
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Faster heating of catalytic converters
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Reduced exhaust emissions following a cold start
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Reduced fuel consumption
A controlled VANOS adjustment unit is mounted at both intake and exhaust camshafts.
A VANOS solenoid valve is used to control the VANOS adjustment unit. The required position of the intake and
exhaust camshaft is calculated using the engine speed and load signal (dependent on intake temperature and
engine temperature). The DME control unit activates the VANOS adjustment unit accordingly.
The control of the intake and exhaust camshaft is variable within their maximum adjustment range.
SBT Engine control for N45, N46 E46, E60, E81, E83, E85, E87, E90, E91, E92, E93
BMW AG - TIS
20.01.2013 20:52
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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