Programmed ignition system (page 2 of 2)

Crankshaft position (CKP) sensor The speed and position of the engine are detected by the crankshaft position (CKP) sensor which projects through the engine adapter plate. A critical air gap exists between the CKP sensor and the flywheel, which is essential to allow correct engine operation.

The flywheel incorporates a reluctor ring which consists of 32 poles spaced at 10° intervals, with 4 missing poles at 30° , 60° , 210° and 250° . The missing poles inform the ECM when to operate the injectors, with the remaining poles providing a continual update of crankshaft position and engine speed. As the flywheel rotates, each pole that passes the CKP sensor disturbs the magnetic field created by the sensor inducing a voltage pulse in the coil. The CKP sensor is monitored by the ECM on UP and WU wires.

Camshaft position (CMP) sensor The camshaft position sensor has two functions; the first is to enable the ECM to run a sequential fuelling mode; the second is to measure the actual cam period, this measurement is achieved using teeth on the camshaft to indicate when the valve opens and closes. The CMP sensor is monitored by the ECM on BU and RY wires.

Manifold absolute pressure (MAP) sensor The manifold absolute pressure sensor is mounted directly on the inlet manifold and provides the ECM with an accurate representation of the load placed on the engine. This allows the ECM to adjust the quantity of fuel being injected together with the ignition timing, to achieve optimum fuelling of the engine. The MAP sensor achieves this by detecting pressure variations inside the manifold, then converting these variations into graduated electrical signals which are monitored by the ECM on RG and YP wires to determine engine load. Earth supply is on a KB wire.