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: When the engine RPM falls below a lower limit of a target RPM of idling while an engine is in an idle operation, a control valve is shifted to the open-loop control mode instead of the conventional feedback control mode so as to enable the engine RPM range to be quickly increased up to within the target RPM of idling rotations. Said control valve is disposed in a bypass which communicates with the upstream side and the downstream side of the throttle valve in intake passage to adjust the volume of an inspired air. The solenoid current command (amount of control) for adjusting the opening degree of the control valve during the period of the open-loop control mode is set at a level higher than that immediately before the feedback control mode shifts to the open-loop control mode.

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 fuel supply control control method for an internal combustion engine, which is adapted to determine a quantity of fuel for supply to the engine by multiplying a basic value of the quantity of fuel determined as a function of at least one operating parameter of the engine, by correction coefficients dependent upon operating conditions of the engine, and adding to the basic value correction variables dependent upon operating conditions of the engine, and to supply the determined quantity of fuel to the engine. Values of predetermined one of the above correction coefficients and predetermined one of the above correction variables are determined, which correspond to a set desired value of output voltage of a single voltage creating means. The basic value of the quantity of fuel is corrected by the determined values of the predetermined one correction coefficient and the predetermined one correction variable through multiplication and addition, respectively, to determine the quantity of fuel.

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 of detecting abnormalities through fault diagnosis applied to at least one input unit or output unit by an electronic control unit to which the input unit or output unit is connected. The method comprises the steps of subjecting the input unit or output unit to fault diagnosis, storing information, which is indicative of abnormality, in a first storage area of the electronic control unit when the abnormality is detected as the result of the diagnosis, storing information, which is indicative of the abnormality, in a second storage area of the electronic control unit when the abnormality is detected as the result of subjecting the input or output unit to fault diagnosis again, and rendering a decision to the effect that the input unit or output unit which has undergone the fault detection operation is abnormal when it is determined that the contents stored in the first and second storage areas are identical.

Abstract: A method of controlling the supply of fuel to an internal combustion engine, wherein the value of at least one operating parameter of the engine is detected in synchronism with generation of pulses of a control signal generated at predetermined crank angle positions of the engine, and fuel is supplied to the engine in a quantity responsive to the detected value of the at least one operating parameter.

Abstract: A fuel supply control method of controlling the quantity of fuel being supplied to an internal combustion engine after cranking thereof. Upon generation of a predetermined control signal immediately after the cranking of the engine, an initial value of a fuel increment is set, which corresponds to the engine temperature. Subsequently, the set initial value is decreased at a predetermined rate upon each generation of the predetermined control signal. A quantity of fuel is set by the use of the thus decreased value of the fuel increment and supplied to the engine in synchronism with generation of the predetermined control signal. When the fuel increment has a value larger than a predetermined reference value, the value of the fuel increment is decreased at a first rate, while when it has a value smaller than the predetermined reference value, it is decreased at a second rate smaller than the first rate.

Abstract: A control method of supplying an internal combustion engine with required quantities of fuel appropriate to operating conditions of the engine, in synchronism with pulses of a control signal generated at predetermined crank angle positions of the engine. When the engine is operating in a predetermined accelerating condition, a correction variable for increasing the fuel supply quantity for supply to the engine at acceleration is determined as a function of the number of pulses of the above control signal generated after the predetermined accelerating condition has been detected for the first time, as well as of the rate of change of the value of a predetermined operating parameter indicative of the engine load which is detected in synchronism with a predetermined sampling signal, to thereby set a quantity of fuel for supply to the engine at acceleration.