Misfire Counters

Misfire Counters:

The misfire counters graphic illustrates how the misfire diagnosis and the diagnostic executive use the misfire counters or accumulators. When a misfire diagnostic test fails and reports to the diagnostic executive that a misfire condition exists, the diagnostic executive reviews all of the misfire counters in order to store the most current misfire information.

In the example illustrated by the misfire counters graphic, a misfire DTC has been set and the misfires are stored in more than one history misfire counter or accumulator. The cylinder number 1 history misfire and current misfire counters indicates more misfires than the other cylinders. The misfires stored in the cylinder number 2 and the cylinder number 4 history misfire counters or accumulators indicate the erratic rotation of the crankshaft caused by the misfire of number 1 cylinder. In this example, viewing the current misfire and history misfire counters indicate that a true misfire is present and the malfunction is located at cylinder number 1.

Use a scan tool in order to monitor the misfire counters data. Identify which cylinder or cylinders are misfiring. Inspect the systems and components common to the cylinders if multiple cylinders indicate a misfire is present.