Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The Misfire Monitor gathers and filters engine crank speed data for 10.0 seconds once the monitor conditions are met. If the crank speed deviation for a cylinder is less than a calibrated value, a misfire fault is set for that cylinder. If more than one cylinder is failed, a multiple cylinder misfire fault is set in addition to the individual faults of the failed cylinders. The engine must be at operating temperature and must not be in active aftertreatment regeneration mode in order to run this monitor. The PCM illuminates the MIL lamp after the diagnostic runs and fails twice in a row. During this time the customer may experience a cylinder miss or engine stumble. The PCM will turn off the MIL lamp once the monitor runs and passes in three consecutive diagnostic runs or drive cycles (which ever comes later).