Abstract: A spark advance control system includes a high octane value spark advance schedule and a regular octane value spark advance schedule, respectively including advance limits and retard limits at different spark advance angles. Spark advance control schedules are selected during normal spark advance control operation. The high octane value spark advance schedule is selected when spark advance is maintained at an angular value higher than a predetermined regular-to-high octane value schedule switching, which is set near an advance limit in the regular octane value spark advance schedule. In the alternative, the regular octane value spark advance schedule is selected when spark advance is maintained at an angular value lower than a predetermined high-to-regular octane value schedule switching criterion, which is set near the retard limit in the high octane value spark advance schedule.

Abstract: A system and method for controlling an ignition timing for an internal combustion engine. In the ignition timing control system and method, with a retardation angle correction amount stored as a learning value according to an engine operating region, a newly learned learning value is used as the retardation angle correction amount so that an optimum retardation angle correction amount can be provided regardless of an individual difference in engine performance and of an operating environment. Consequently, an effective suppression of occurrence of engine knocking can be achieved and engine performance and fuel economy can be improved. In addition, since the updating of the learning value is inhibited only when an engine revolutional speed is increased, an opportunity of updating the learning value is increased so that the learning value can always be set at optimum.

Abstract: A method and an apparatus for controlling supercharge pressure for a turbocharger in which a target value of supercharge pressure is set up in accordance with the operating conditions of the engine and a basic control amount for a control valve for controlling the exhaust gas flow to an exhaust gas turbine is also set up in accordance with the operating conditions of the engine, and the basic control amount is corrected in response to the deviation between actual supercharge pressure and a target supercharge pressure value, when performing a feedback control of the supercharge pressure. With this construction, the actual supercharge pressure can accurately and stably be controlled to the target value required in accordance with the operating conditions of the engine.