Abstract: In a variable valve timing structure for changing the opening/closing timing of the intake valve and/or the exhaust valve by changing the rotation phase of a cam shaft corresponding to a target value, wherein the deviation between the actual rotation phase at the point of time after a predetermined time has passed from a step-change of the target value and the target value after the step-change is equal to or above a predetermined value, an abnormality of response characteristic of the variable valve timing structure is judged.

Abstract: In a hydraulic type variable valve timing structure having a construction for changing a phase of a cam shaft by controlling the current provided to a linear solenoid valve, and a change of said rotational phase corresponding to the increase of said current is limited by a stopper, a maximum current is provided for a predetermined time to the linear solenoid valve when a target value of the rotational phase is switched to the rotational phase being limited by the stopper, and thereafter, the current is lowered and maintained in the range where the rotational phase being limited by the stopper can be maintained.

Abstract: The invention relates to a method and apparatus for diagnosing an abnormality in an internal combustion engine fuel temperature detection apparatus, by comparing fuel temperature detection values with other detection values for cooling water temperature and intake air temperature. The arrangement is such that when there are large changes in the detection values for the respective temperatures, diagnosis is interrupted, thus enabling the prevention of erroneous diagnosis at the time of hot start and the like when changes in the respective detection values are large.

Abstract: In a method and apparatus for diagnosing a trouble in supercharging pressure defecting means in an internal combustion engine which is provided with a throttle valve at the downstream side of a compressor of a supercharger and a means for detecting a supercharging pressure, the trouble of the supercharging pressure detecting means is diagnosed based on the variation in the detecting value of the supercharging pressure upon at the transient operation of the engine, or by comparing the flow rate of an intake air detected at the upstream side of the compressor, the flow rate of an intake air calculated based on the variation in the supercharging pressure during the transient operation of the engine, and the detecting values of the flow rate of an intake air.Thus, the trouble of the supercharging pressure detecting means can be diagnosed based on the detecting values during the transient operation of the engine only with a software processing and without setting a particular diagnosis period.

Abstract: The invention involves stopping the operation of an internal combustion engine, when actual vehicle deceleration is detected after a vehicle deceleration operation. Alternatively, under conditions wherein it is possible to shut off fuel supply at the time of the deceleration operation, the invention involves stopping the operation of the engine by shutting off the fuel supply to some cylinders, and then shutting off the fuel supply to all cylinders when actual vehicle deceleration is detected. Since the fuel supply to the engine is timed to be shut off when the vehicle is decelerated, the speed is reduced smoothly without an accompanying large torque change. Thus, vehicle ride comfort and fuel consumption can be improved.