Cylinder Identification Sensor

SECONDARY IGNITION CIRCUIT MONITORING - M1.X SYSTEMS (except M1.71M42)







The cylinder identification input is needed by the M 1 .X Systems to initiate semi- sequential fuel injection operation. This input is also used on some models as a teed back signal for secondary ignition circuit operation (catalyst protection).

The inductive sensor consisting of a coil of wire, is installed on the #6 high tension lead to the spark plug. The M70 V12 has an additional sensor on #12 high tension lead.

The magnetic field created by the current flow through the secondary lead induces an AC pulse, and an input to the ECM, for every two revolutions of the engine.

CYLINDER IDENTIFICATION SENSOR







The cylinder ID sensor input to the control module is used to determine piston position in relation to valve timing. It is used by the control module to establish the firing order for the direct ignition system and to set up the injector triggering for fully sequential system.

Depending on the system the sensor is either an analog inductive pulse sensor similar to the crankshaft position sensor or a hall effect sensor.

- Inductive pulse sensor: M1.7/M42, M3.1 and M3.3
- Hall effect sensor: M3.3.1

The inductive pulse sensor scans a tooth or pin mounted on the intake camshaft drive gear. The A/C voltage generated when the tooth passes the sensor tip provides one pulse per revolution of the camshaft.

The hall sensor produces a square wave pulse per revolution of the camshaft.



CYLINDER IDENTIFICATION SIGNAL (SIEMENS SYSTEMS)







An angle pulse generator is used for the camshaft position sensing. This sensor consists of two windings (primary and secondary) that are connected together at one end, and a magnetic core. The primary winding is supplied with a 120 kHz AC signal.

The magnetic coupling causes an induced voltage1 at the same frequency, to be induced into the secondary winding. However the induced voltage has a slight phase shift due to the induction time delay.

The trigger wheel of the camshaft influences the magnet field of the sensor and causes the phase shift to increase as the disc of the wheel moves closer to the sensor. The MS41.1 Control Module sees this change in phase shift as the TDC compression input from the camshaft. When the disc passes by the sensor the phase shift moves closer again.

The MS41.1 Control Module uses the signal from the cam sensor to set up the triggering of the ignition coils through the firing order and for activation of fully sequential fuel injection.

There is no replacement value for the camshaft sensor. However, a faulty sensor input will cause the MS41.1 Control Module to activate double ignition for the coil firing and trigger the injectors in parallel injection.

The camshaft position sensor is monitored as part of the requirements for OBD II emission control. A faulty sensor input will be logged in the MS41.1 Control Module memory and if the OBD II criteria is satisfied, the Check Engine Lamp will illuminate.