Patent ID: 7267103

Claim:
An ignition timing control system for an internal combustion engine, comprising: in-cylinder pressure-detecting means for detecting pressures in a plurality of cylinders as a plurality of in-cylinder pressures, respectively; work-done-amount parameter-calculating means for calculating a plurality of work-done-amount parameters indicative of amounts of work done in combustion in the cylinders, according to the detected in-cylinder pressures, respectively; target value-calculating means for setting one of the calculated work-done-amount parameters to a reference value of the work-done-amount parameters, and calculating one target value as a target of the work-done-amount parameters, according to the reference value; and ignition timing-determining means for determining ignition timings of the cylinders, respectively, such that the work-done-amount parameters follow the one target value, wherein, the reference value is set to a minimum value of work-done-amount parameters within a range defined between the maximum value of the work-done-amount parameters as an upper limit and a value of the work-done-amount parameters smaller than the maximum value by a predetermined value, as a lower limit.