Abstract: An addition correction term is added to a feedback control term when an internal combustion engine is idling, a control valve is under feedback control, and an automatic transmission is in drive range (D range). The addition correction term is calculated by multiplying a predetermined constant value by at least one of several correction coefficients which are based on RPM and temperatures of the engine and vehicle speed. A learnt value is calculated based on intake manifold pressure when the internal combustion engine is in idling condition, the control valve is under feedback control, and the automatic transmission is in disengagement condition, for example, neutral range (N range). When the automatic transmission is turned into D range the existing manifold pressure is detected and the addition correction term is calculated based on the difference between the learnt value and the detected manifold pressure.

Abstract: When the rotational speed of an internal combustion engine is decreasing, the rate of decrease in engine rotational speed as well as the engine rotational speed are sensed. A command value dependent upon both the engine rotational speed and the speed decrease rate is generated when the engine rotational speed falls below a predetermined value, for regulating the opening of a control valve arranged in a bypass passage bypassing the engine throttle valve, to control the amount of intake air and, hence, the idling speed of the engine. Generation of the command value is terminated when the speed decrease rate falls below a predetermined threshold value preset in dependence upon engine rotational speed. Thus, the command value is outputted for a period of time which is not fixed in advance but which is controlled in dependence upon both engine rotational speed and the speed decrease rate, thereby enabling the rotational speed of the engine to be stabilized smoothly at the target idling rotational speed.

Abstract: A method and apparatus are provided for controlling the solenoid current of a solenoid valve which controls the amount of suction air in an internal combustion engine. An actual current flowing through the solenoid is detected and a solenoid current control value is calculated as a function of engine operating conditions. A corrected solenoid current control value is determined as a function of the solenoid current control value and a feedback control term is calculated as a function of the difference between the corrected solenoid current control value and the actual solenoid current. An initial value for the feedback control term is determined as a function of an integration term which forms part of the feedback control term. A pulse duration signal is determined as a function of the corrected solenoid current value and an output pulse duration signal is calculated as a function of the pulse duration signal and the feedback control term.

Abstract: An addition correction term is added to a feedback control term when an internal combustion engine is idling, a control valve is under feedback control, and an automatic transmission is in drive range (D range). The addition correction term is calculated by multiplying a predetermined constant value by at least one of several correction coefficients which are based on RPM and temperature of the engine and vehicle speed. A learnt value is calculated based on intake manifold pressure when the internal combustion engine is in idling condition, the control valve is under feedback control, and the automatic transmission is in disengagement condition, for example, neutral range (N range). When the automatic transmission is turned into D range, the existing manifold pressure is detected and the addition correction term is calculated based on the difference between the learnt value and the detected manifold pressure.

Abstract: A method and apparatus are provided for controlling the solenoid current of a solenoid valve which controls the amount of suction air in an internal combustion engine. The actual solenoid current flowing through the solenoid is detected and a solenoid current control valve is calculated as a function of engine operating conditions. A corrected solenoid current control value is determined as a function of the solenoid current control value and a pulse duration signal is determined as a function of the corrected solenoid current control value. A feedback control term is calculated as a function of the actual solenoid current and the corrected solenoid current control value. Further, a temperature corresponding to the solenoid temperature is detected and a temperature correction value is generated corresponding thereto.

Abstract: A fuel supply control method for an internal combustion engine. Sensors read out values for engine speed, intake pipe absolute pressure and exhaust passage absolute pressure. These values are used to determine a basic fuel supply value and a fuel supply correction value and these derived values are, in turn, used to determine the amount of fuel to be supplied to the engine.

Abstract: Feedback control of the opening area of a bypass which is provided in parallel with a throttle valve of an engine is conducted immediately after the cranking is completed, based on the deviation of existing RPM from the target RPM which is memorized as the function of the engine temperature in advance, to maintain the idling RPM of the engine at optimum level in the state of after-cranking without being affected by the possible change in viscosity of engine oil, the variations in temperatures of the ambient air and the engine cooling water, the load of engine, and so on. The control signals for the feedback control are learned when the existing RPM are substantially equal to the target RPM and stored in a memory. One of the learned values is read out for fixing a control signal in the beginning of the state of after-cranking so that the RPM of the engine is smoothly approximated to the target RPM when the engine shifts from the during-cranking state to the idling state.

Abstract: An air-fuel ratio control method for an internal combustion engine having a plurality of cylinders divided into at least two cylinder groups, wherein when each of the cylinder groups is in a first predetermined operating condition, the air-fuel ratio of a mixture being supplied to the each cylinder group is controlled in a feedback manner responsive to the output of corresponding one of at least two exhaust gas ingredient concentration sensors arranged in respective ones of at least two exhaust passage divided portions connected to respective cylinder groups, while when the each cylinder group is in a second predetermined operating condition, the air-fuel ratio of the mixture is controlled in an open loop mode corresponding to the second predetermined operating condition.

Abstract: A fuel injection timing control method for an internal combustion engine, wherein fuel injection is effected over a fuel injection period determined based on engine operation parameters from predetermined fuel injection beginning relative to a predetermined crank angle position. The predetermined fuel injection beginning is corrected by a correction value obtained by multiplying the determined fuel injection period by a predetermined coefficient, to thereby determined desired fuel injection beginning. Preferably, the predetermined fuel injection beginning is corrected not only by the above correction value but by a second correction value based on the delay time that elapses from the moment fuel is injected until it is actually drawn into the engine cylinder.

Abstract: A fuel supply control method for an internal combustion engine. Sensors read out values for engine speed, intake pipe absolute pressure and exhaust pipe absolute pressure. These values are used to determine a corrected value of intake pipe absolute pressure which, in turn, is used to determine the amount of fuel to be supplied to the engine.

Abstract: An intake air quantity control method for an internal combustion engine at idle. A supplementary air quantity to be supplied to the engine through a first auxiliary air passage bypassing an engine throttle valve is controlled by a first control valve on the basis of a basic value of a control amount corresponding to the difference between actual engine speed and desired idling speed. A supplementary air quantity to be supplied to the engine through a second auxiliary air passage is controlled by a second control valve in response to engine temperature. A first correction value is calculated based upon detected atmospheric pressure encompassing the engine, and a second correction value based upon detected engine temperature and atmospheric pressure, respectively. The basic value of the control amount is corrected by means of the first and second correction values, and the first control valve is driven according to the corrected control amount basic value.

Abstract: A method for controlling air-fuel ratio of the mixture to be supplied to the engine detects whether or not the amount of the fuel to be supplied to the engine is greater than a reference amount. A feedback control in which the air-fuel ratio is corrected according to an oxygen concentration in the exhaust gas is performed when the amount of the fuel to be supplied to the engine is equal to or smaller than the reference level, while an open loop control in which the air-fuel ratio of the mixture is determined irrespective of the oxygen concentration is performed if the amount of the fuel to be supplied to the engine is greater than the reference level. The reference amount is changed depending on the engine rotational speed so as to eliminate the overlap of a range of the fuel increment control and a range of the feedback control and greatly improve the driveability of the engine during high load operating conditions of the engine.

Abstract: A method for controlling fuel supply of an internal combustion engine includes steps of sampling a vacuum level within an intake pipe of the engine and a value corresponding to engine rotational speed at predetermined sampling intervals, generating a subtraction value .DELTA.M.sub.e between a latest sampled value M.sub.en of the value corresponding to the engine rotational speed and a sampled value M.sub.en-m sampled predetermined number of cycles before, and correcting a latest sampled value P.sub.BAn of the pressure within the intake pipe in accordance with the subtraction value .DELTA.M.sub.e. The fuel supply amount is determined according to a corrected value P.sub.BA of the pressure within the intake pipe of the engine obtained by the above correction process.

Abstract: An apparatus is provided for controlling the supply of fuel to internal combustion engine having a control valve for controlling the amount of air to be supplied to an engine piston downstream of a throttle valve. The apparatus comprises a detector for detecting any disorder in the amount of air and for providing a disorder indicating signal. An engine speed sensor detects the rotating speed of the engine and a throttle opening sensor detects the degree of opening of the throttle valve. A fuel cut circuit is coupled to the disorder detector, the engine speed sensor, and the throttle opening sensor for storing a fuel cut area defined by the degree of throttle opening and the rotating speed of the engine. The fuel cut circuit produces, in response to the disorder indicating signal, a fuel cut command signal when the outputs of the engine speed sensor and the throttle opening sensor indicate that the engine is operating within the fuel cut area.

Abstract: A fuel supply of an internal combustion engine is controlled by sampling a vacuum level within an intake pipe of the engine and a value corresponding to the engine rotational speed at predetermined sampling intervals, subsequently correcting a latest sampled value P.sub.BAn of the vacuum level with a latest sampled value M.sub.en of the value corresponding to the engine rotational speed to produce a corrected value P.sub.BA, and then determining fuel supply amount in accordance with the corrected value P.sub.BA. By determining the fuel supply amount in this way, hunting of the engine rotational speed especially during idling operation of the engine is prevented.

Abstract: A method for controlling the quatity of fuel being supplied to an internal combustion engine, immediately after termination of a fuel cut operation which is carried out when the engine is operating in a predetermined operating region while it is decelerating. The fuel quantity is controlled to a required value after termination of a fuel cut operation, by increasing a quantity of fuel set at least as a function of intake pipe pressure by an increment which is set in synchronism with generation of pulses of a predetermined control signal. The increase of the fuel quantity is effected for a period of time after a transition of the operative state of the engine from the fuel cut operation to a normal operation wherein fuel supply is effected has been detected and before a predetermined number of pulses of the above control signal are generated, so long as the magnitude of a variation or change in the rotational speed of the engine is determined to be larger than a predetermined value.

Abstract: A method for controlling the quantity of fuel being supplied to an internal combustion engine, immediately after termination of a fuel cut operation which is carried out when the engine is operating in a predetermined operating region while it is decelerating. The fuel quantity is controlled to a required value after termination of a fuel cut operation, by increasing a quantity of fuel set at least as a function of intake pipe pressure by an increment which is set in synchronism with generation of pulses of a predetermined control signal. The increase of the fuel quantity is effected for a period of time after a transition of the operative state of the engine from the fuel cut operation to a normal operation wherein fuel supply is effected has been detected and before a predetermined number of pulses of the above control signal are generated, so long as the magnitude of a variation or change in the rotational speed of the engine is determined to be larger than a predetermined value.