Abstract: A fuel injection timing control system for a direct injection spark ignition internal combustion engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion. In the system, a fuel injection start timing limit by which injection of the determined fuel injection amount should be started and a fuel injection end timing limit by which injection of the determined fuel injection amount should be ended are determined based at least on the detected engine speed in accordance with predetermined data so as to avoid smoke from occurring in the engine, and when a determined fuel injection amount can not be injected within a time of period defined by the limits, a desired fuel injection start or end timing or the determined fuel injection amount is corrected, thereby ensuring the engine torque drop to a minimum extent, while surely avoiding smoke to occur.

Abstract: A system for controlling a temperature of an air-fuel ratio sensor heater of an direct injection spark ignition engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion. In the system, the temperature of the air-fuel ratio sensor is estimated and the supply of current to the heater is determined in terms of a duty ratio in PWM based on the estimated temperature of the air-fuel ratio sensor and is increased when the engine is determined to be operated at the ultra-lean burn combustion. The duty ratio is increased by an augmentative on-time which is determined based on a parameter such as a desired torque, an engine speed and load, or a vehicle speed. The supply of current is also increased when the operation of the EGR is in progress.

Abstract: An ignition timing control system for a direct injection spark ignition internal combustion engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion. In the system, a desired fuel injection end timing at which injection of the determined fuel injection amount should be ended is determined. Then, the difference between the desired fuel injection end timing and the ignition timing is calculated and is determined whether the difference is less than a predetermined value (crank angle margin), and the ignition timing is corrected by the predetermined value when the difference is determined to be less than the predetermined value, thereby enabling to prevent the overlapping of the fuel injection end timing and the ignition timing from happening and avoiding the problem of misfiring or residual of unburned fuel in the cylinder from occurring.

Abstract: An allowable range (adaptive allowable range) for limiting a manipulated variable generated in order to converge the difference between an output from an O2 sensor disposed downstream of a catalytic converter and a target value thereof to “0” is sequentially updated depending on how the manipulated variable deviates from the allowable range.