Abstract: An internal combustion engine includes an electronic controller programmed to determine, for at least one combustion event in a combustion chamber, a theoretical polytropic constant, a measured polytropic constant, and a difference between the theoretical polytropic constant and the measured polytropic constant. The electronic controller is further programmed to calculate an adjusted pressure signal based on the pressure signal and the difference such that the adjusted pressure signal compensates for changes to an accuracy of the pressure sensor over time.

Abstract: An internal combustion engine includes an electronic controller programmed to determine, for at least one combustion event in a combustion chamber, a theoretical polytropic constant, a measured polytropic constant, and a difference between the theoretical polytropic constant and the measured polytropic constant. The electronic controller is further programmed to calculate an adjusted pressure signal based on the pressure signal and the difference such that the adjusted pressure signal compensates for changes to an accuracy of the pressure sensor over time.

Abstract: A pressure sensor disposed to sense an engine cylinder pressure provides a pressure signal, and an engine timing sensor provides an engine timing signal to an electronic controller, which is programmed to receive and analyze the pressure and engine timing signals to determine a misfire signal, a peak pressure signal, a pressure rise rate, an actual ignition signal, and a center of combustion signal. The electronic controller is further programmed to activate a fault flag when at least one of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, indicates that an abnormal combustion is present in the cylinder.

Abstract: An electronic controller for an engine is programmed to operate in a prognostic mode, in which a baseline record of combustion parameters is created and stored in non-volatile memory, and in a diagnostic mode, in which an operating set of combustion parameters is compiled. During operation, the electronic controller retrieves the baseline record and compares it with the operating set to determine, in real time during engine operation, whether an abnormal combustion is present in the cylinder. The electronic controller activates at least one failure flag when the abnormal combustion is determined to be present.

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.