Volkswagen 1.9 tdi, Owner'S Manual, Page: 35 / 67

Engine Management
31
Cylinder recognition when
starting the engine
When starting the engine, the Diesel Direct
Fuel Injection Engine Control Module J248
must determine which cylinder is in the
compression stroke in order to activate the
correct pump/injector valve. To achieve this,
it evaluates the signal generated by the
Camshaft Position Sensor G40, which
scans the teeth of the camshaft sensor
wheel to determine the camshaft position.
Camshaft sensor wheel
Since the camshaft executes one
360-degree revolution per working cycle,
there is a tooth for each individual cylinder
on the sensor wheel. These teeth are
spaced 90 degrees apart.
To differentiate between cylinders, the
sensor wheel has an additional tooth with
different spacing for each of cylinders
1, 2, and 3.
SSP209/094
Cylinder 2
Cylinder 1
Cylinder 3
Cylinder 4
90
°