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 homogenous charge compression ignition engine is operated by compressing a charge mixture of air, exhaust and fuel in a combustion chamber to an autoignition condition of the fuel. The engine may facilitate a transition from a first combination of speed and load to a second combination of speed and load by changing the charge mixture and compression ratio. This may be accomplished in a consecutive engine cycle by adjusting both a fuel injector control signal and a variable valve control signal away from a nominal variable valve control signal. Thereafter in one or more subsequent engine cycles, more sluggish adjustments are made to at least one of a geometric compression ratio control signal and an exhaust gas recirculation control signal to allow the variable valve control signal to be readjusted back toward its nominal variable valve control signal setting.