Patent ID: 8185293

Claim:
A method of operating an internal combustion engine, the method comprising: monitoring a pressure in a combustion chamber of the engine during a compression stroke; determining whether a fuel composition has changed from a first composition to a second composition based at least in part on the monitored pressure; in response to a determination that the fuel composition has changed, activating a fuel composition adaptation; after activating the fuel composition adaptation, determining that the fuel composition has reached a steady-state condition; in response to a determination that the fuel composition has reached the steady-state condition, deactivating the fuel composition adaptation; and after deactivating the fuel composition adaptation, determining whether the fuel composition has changed from the second fuel composition to a third fuel composition based at least in part on the monitored pressure; wherein monitoring the pressure in the combustion chamber of the engine includes determining a characteristic feature of the fuel that is a function of the pressure in the combustion chamber of the engine during the compression stroke.