1 Series E81 118i (N46T) 3-door
Once the correct camshaft position has been reached, the VANOS solenoid valves ensure that the oil volume in
the servo control cylinders in both chambers remains constant. This keeps the camshafts in this position.
To perform the adjustment, the variable camshaft control requires an information signal on the current position of
the camshaft. Camshaft sensors on the intake and exhaust end record the position of the camshafts.
When the engine is started, the inlet camshaft is in the end position ("retarded" position). When the engine is
started, the exhaust camshaft is pretensioned by a spring and held in the "advanced" position.
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 period 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 injection valve 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
•
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
SBT Engine control for N45, N46 E46, E60, E81, E83, E85, E87, E90, E91, E92, E93
BMW AG - TIS
19.01.2013 06:11
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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