Abstract: A fuel injection amount control apparatus for an engine comprises injectors for injecting fuel to an engine and an electronic control unit (ECU) for controlling the injectors. The ECU learns the deviation between the air-fuel ratio of a flammable mixture to be supplied to the engine and the target value. The ECU controls the amount of fuel injection to the engine by reflecting the learning value on the computation of the injection amount. The engine has intake valves, exhaust valves and an apparatus for altering the open/close characteristics of the intake valves. The ECU computes the learning value of the air-fuel ratio in accordance with the behavior of the characteristic altering apparatus and the running conditions of the engine. When the coolant temperature of the engine is low and the learning value is not renewed, the ECU compensates the already updated learning value to a smaller value.

Abstract: A cam shaft of an engine is provided with a timing change mechanism (VVT) which is driven by hydraulic pressure to alter the timing of a intake valve (valve timing). This VVT is controlled to change the valve overlap of the intake valve and an exhaust valve, thereby adjusting the suction and exhaust in and from a combustion chamber. To control the VVT, an electronic control unit (ECU) computes a target value for the valve timing in accordance with the running condition of the engine and controls the supply of the hydraulic pressure to the VVT based on the target value. The ECU determines the level of the actual hydraulic pressure given to the VVT. When the actual valve timing does not lie in a predetermined range with respect to the target value, the ECU determines that an abnormality has occurred in the VVT, and executes a predetermined fail safe routine. When the hydraulic pressure is equal to or smaller than a reference value, the ECU suppresses VVT malfunction determinations.

Abstract: A cam shaft of an engine is provided with a timing change mechanism (VVT) which is driven by hydraulic pressure to alter the timing of a intake valve (valve timing). This VVT is controlled to change the valve overlap of the intake valve and an exhaust valve, thereby adjusting the suction and exhaust in and from a combustion chamber. To control the VVT, an electronic control unit (ECU) computes a target value for the valve timing in accordance with the running condition of the engine and controls the supply of the hydraulic pressure to the VVT based on the target value. The ECU determines the level of the actual hydraulic pressure given to the VVT. When the actual valve timing does not lie in a predetermined range with respect to the target value, the ECU determines that an abnormality has occurred in the VVT, and executes a predetermined fail safe routine. When the hydraulic pressure is equal to or smaller than a reference value, the ECU suppresses WT malfunction determinations.