Patent ID: 8306723

Claim:
A method to operate a direct-injection compression ignition multi-cylinder internal combustion engine, comprising: operating the engine under a predetermined condition comprising a fuel cut-off mode; controlling fuel pressure to a predetermined pressure level; actuating a fuel injector for a first cylinder during each cylinder event at pulsewidths adjusted from a nominal minimum pulsewidth and monitoring a combustion parameter for the first cylinder, wherein actuating the fuel injector for the first cylinder during each cylinder event at pulsewidths adjusted from the nominal minimum pulsewidth comprises, setting an initial pulsewidth less than the nominal minimum pulsewidth, and monotonically increasing the pulsewidth of the fuel injector for the first cylinder from the initial pulsewidth during successive cylinder events, wherein monotonically increasing the pulsewidth comprises increasing the pulsewidth during each successive cylinder event relative to the pulsewidth of the immediately preceding cylinder event; detecting a discernable change in the state of the combustion parameter in the first cylinder and determining a corresponding pulsewidth; and adjusting the nominal minimum pulsewidth to the pulsewidth corresponding to the discernable change in the state of the combustion parameter in the first cylinder.