Low Data Rate (LDR) System
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The LDR misfire monitor uses a low data rate CKP sensor signal which indicates one position reference at 10 degrees before top dead center (BTDC) for each cylinder event. The PCM uses the CKP sensor signal to calculate the crankshaft speed and acceleration for each cylinder. The crankshaft acceleration is then processed to detect a sporadic, single-cylinder misfire patterns or multi-cylinder misfire patterns. The changes in overall engine RPM are removed by subtracting the median engine acceleration over a complete engine cycle. The resulting deviant cylinder acceleration values are used in evaluating misfire. Refer to the GENERIC MISFIRE PROCESSING for more information.