Onboard diagnostic misfire detection monitor for internal combustion engines

摘要

A misfire monitoring method and system employ an indicated mean effective pressure (IMEP) parameter for misfire monitoring of an internal combustion engine of a vehicle. The method and system include determining displacement and torque of the engine. An indicated mean effective pressure (IMEP) parameter is then calculated for the engine. The indicated mean effective pressure (IMEP) parameter is engine torque divided by engine displacement. A misfire monitor monitors the indicated mean effective pressure (IMEP) parameter to detect misfire. The method and system include determining maximum indicated mean effective pressure (IMEP_MAX) parameter for the engine. A normalized indicated mean effective pressure (IMEP_LOAD) parameter for the engine is then calculated. The normalized indicated mean effective pressure (IMEP_LOAD) parameter is the indicated mean effective pressure (IMEP) parameter divided by the maximum indicated mean effective pressure (IMEP_MAX) parameter. Monitoring the indicated mean effective pressure (IMEP) parameter to detect misfire includes monitoring the normalized indicated mean effective pressure (IMEP_LOAD) parameter to detect misfire.