High Data Rate (HDR) System

The HDR misfire monitor uses a high data rate CKP signal which indicates 18 position references per crankshaft revolution. This high resolution signal is processed using 2 different algorithms. The first algorithm is optimized to detect hard misfires on one or more continuously misfiring cylinders. The low pass filter filters the high-resolution crankshaft velocity signal to remove some of the crankshaft torsional vibrations that degrade signal to noise. Two low pass filters are used to enhance detection capability - a base filter and a more aggressive filter to enhance single-cylinder capability at higher RPM. This significantly improves detection capability for continuous misfires on single cylinders up to red line. The second algorithm, called pattern cancellation, is optimized to detect low rates of misfire. The algorithm learns the normal pattern of cylinder accelerations from the mostly good firing events and is then able to accurately detect deviations from that pattern. Both the hard misfire algorithm and the pattern cancellation algorithm produce a deviant cylinder acceleration value, which is used in evaluating misfire in the Generic Misfire Processing section below.

Due to the high data processing requirements, the HDR algorithms may be implemented by the PCM in a separate chip. The chip carries out the HDR algorithm calculations and sends the deviant cylinder acceleration values to the PCM microprocessor for additional processing as described below. The chip requires proper operation of the CKP and camshaft position (CMP) sensor inputs. DTC P1336 sets if the chip detects noise on the CKP sensor input or if the chip is unable to synchronize with the missing tooth location. DTC P1336 points to noise present on the CKP sensor input or a lack of synchronization between the CMP and CKP sensors.