Low Data Rate System

The 6.0L Diesel engine utilizes a variable reluctance sensor that processes the edges of a 60-2 tooth stamped target wheel mounted on the crankshaft (CKP). The software gets an edge every 3 degrees and these edges are
used for fuel injection timing, fuel quantity control along with the calculation of engine speed. The 6.0L utilizes a second variable reluctance sensor (CMP) that processes a peg mounted on the camshaft for cylinder identification.
These two signals are hardware buffered and sent to the Fuel Injector Control Module that performs the injection event.

The LDR Misfire Monitor utilizes the variable reluctance crankshaft (CKP) sensor signal from the 60-2 tooth wheel. There is a missing two-tooth window to provide sync pulses to the CKP sensor along with a CMP peg, which indicates proper camshaft to crankshaft position for correct cylinder timing. The PCM calculates crankshaft rotational velocity for each cylinder from this position signal. The acceleration for each cylinder is then calculated into a percentage delta change decrease in velocity for use by the misfire algorithm. The resulting deviant cylinder acceleration values are used in evaluating misfire.

Misfire is defined as a loss of compression. The amount of compression loss in a cylinder that misfire monitor will detect is referenced as a 3/16" or larger hole in a cylinder or valve train component.

Misfire Algorithm Processing:

The acceleration that a piston undergoes during a normal firing event is directly related to the amount of torque that a cylinder produces. For misfire determination the CKP signal is processed at the peak instantaneous inverse
velocity angle of 90