Bosch Camshaft Sensor Bank 1 & 2 Intake
Hall sensors are used to determine camshaft position and
provide the DME with information regarding camshaft adjustment positions as
well. The signals are needed to allow
the DME to time the injection and ignition as well. The technical aspects of this sensor are
based on the Hall Effect signal generation method. This method allows for exact calculations of
the positions of the intake camshafts; the camshafts have a pressed rotor on
the end of end of the intake camshaft facing the front of the engine. Bank 2 camshaft rotor is also on the rear end
of the intake camshaft as well, but faces the flywheel side.
The hall sensor contains a permanent magnet, 2 hall elements
and a current bearing semi-conductor plate.
The rotating of the tone wheel rotor will cause an interruption of the
magnetic field generated by the hall sensor, when this happens at right angles
a voltage is induced in the hall sensor.
This voltage signal is an on and off digital signal that is representative
of the exact camshaft position and allows for Vario-cam adjustment and
diagnosis.
The DME 5.2.2. uses a simple camshaft rotor with only one
notched tooth. There is also a rotor on
each bank but in different positions.
Bank 1 has the rotor pressed on the intake camshaft on the flywheel end
of the camshaft. Bank 2 has the rotor at
the front of the engine. The signals are
also used to determine cylinder position and for camshaft adjustment diagnosis.
Dme 7.2, 7.8, 7.8_40 camshaft hall position sensors
accurately detect the positions of the camshaft 8 times per shaft revolution,
that works out to 4 times per crankshaft rotation. The DME is able to use the camshaft signals
to enable a quick start feature. The DME
will know the exact camshaft position on engine shutdown, this is stored in the
Dme’s RAM and used on the next startup, this allows the engine controller to
start injection and ignition immediately without having to wait for 16
signals. This allows for an engine start
in less than 1 crankshaft revolution and also can let the car start without a
engine speed sensor signal. Note that
the Dme 5.2.2 does not have this feature and will not start if the engine speed
sensor signal is not received by the DME.
For the Dme to exactly determine the timing of the engine,
it needs to see bank 1 hall sensor and the engine speed sensor reference mark
in a particular position. When this happens the DME will be able to determine
cylinder 1 and 4 positions and then will time and release the ignition and the sequential
injection. This sensor is also used in
conjunction with the knock sensors to determine which cylinder is knocking. The hall sensors are also used for camshaft
position adaptation, this adaptation is needed so that the DME can react to
deviations in timing caused by normal wear on the timing components. If the battery is disconnected this
adaptation is lost, so the DME must readapt the camshaft adaptations via normal
driving.
Problem symptoms
- Faulted hall sensors can
cause hard starts.
- Engine misfire codes with
no actual misfire
- Actual engine misfire
events present
- Vario cam adjustment fault
codes due to erroneous signals
- No or incorrect Vario-cam
adjustment due to erroneous signals
Diagnostic Techniques
A Fault code for a bad hall sensor is not common, so when
you want to make sure that your sensor is operating properly you can use a DSO
to analyze the signals for proper signal generation, compared bank to
bank. You should get a total of 4 on off
signals, reference the diagram for different DME version signals. The use of a DSO will also allow you to
determine if cam timing deviation exists, this is usually caused by a Vario cam
system failure that will be discussed in the timing section.
Example of good 2009 997 Bank 1-2 Cam sensor timing patterns
9PA known good bank to bank intake
timing
987 Known good Intake cam to cam
timing
