Abstract: An on-board diagnostic system for detecting a fault in an ignition system of an engine system having a cylinder is provided. The system includes an indicated mean effective pressure (IMEP) monitoring module for monitoring IMEP indicating average pressure in the cylinder during an operation cycle of the cylinder for an engine runtime. A misfire detection module detects misfire cycles associated with the cylinder based on the monitored IMEP. An ignition system diagnostic module communicatively coupled to the misfire detection module includes a statistical module and a control module. The statistical module determines a percentage of the misfire cycles during the engine runtime. The control module changes an operational parameter of the engine system when the percentage of the misfire cycles is less than a pre-defined threshold value or provides a warning message for required maintenance when the percentage of the misfire cycles is greater than the pre-defined threshold value.

Abstract: A diagnostic system for an internal combustion engine includes a pressure sensor configured to measure pressure within a combustion cylinder. An electronic controller is configured to receive a pressure signal from the pressure sensor, analyze the pressure signal by at least partially comparing the pressure signal to a predetermined pressure signal, and diagnose a failure of one or more piston ring seal(s), an intake valve, and an exhaust valve of the engine based on a difference between the pressure signal and the predetermined pressure signal.