Abstract: An air-fuel ratio control system for an internal combustion engine in which an exhaust sensor is located in an exhaust path of the internal combustion engine. A control means provides feedback control to match an air-fuel ratio with a target value in accordance with a detection signal from the exhaust sensor. The control means is provided with a correction section which, upon fulfillment of predetermined implementation conditions of correction determination, detects a response time that elapses from the occurrence of a change in an operating state of the internal combustion engine until the detection signal from the exhaust sensor issues a determination signal value. The correction section governing the feedback control of the air-fuel ratio corrects the feedback control in accordance with the detected response time.

Abstract: A control system in an automobile has a controller to provide an air-to-fuel ratio leaner than an ideally combustible air-to-fuel ratio when a lean control range of engine operating conditions is detected, and a controller to increase an air flow rate so as to enrich a fuel mixture when an engine operating condition is transitional to the lean control range. The control system conducts sequentially the lean control and the enrich control according to transitional patterns to the lean control range.

Abstract: An air-fuel ratio control system for an engine, to which evaporated fuel in a canister is supplied, is used for feedback controlling an air-fuel ratio based on a feedback control value calculated according to the quantity of evaporated fuel supplied to the engine. A calculation is made, in a first range of engine operating conditions, of a difference of a first control value between the first control value determined during supplying of the evaporated fuel to the engine and the first control value determined during not supplying of the evaporated fuel to the engine in the first range. A second control value for a second range of engine operating conditions is established different from the first range based on a feedback control value for controlling an air-fuel ratio of fuel in the first range, a ratio of the quantity of intake air into the engine between the first and second ranges, and a ratio of the supplying quantity of the evaporated fuel into the engine between the first and second ranges.

Abstract: An air-to-fuel ratio control system optimally controls an air-to-fuel ratio of an internal combustion engine according to various engine operating conditions, and aims at assuring quick air-to-fuel ratio control and preventing erroneous operation of the engine. With this control system, a corrective amount of fuel to be supplied is determined according to a deviation .DELTA.(A/F) of a measured air-to-fuel ratio (A/F).sub.i and a target air-to-fuel ration (A/F).sub.OBJ. This corrective amount of the fuel is kept in an allowable range defined by limits K.sub.LMIN and K.sub.LMAX, or K.sub.RMIN and K.sub.RMAX. Therefore, the engine is supplied with the fuel which is controlled according to a target fuel amount LT.sub.INJ determined by the correct fuel amount. The control system is responsive to various engine operating conditions, and protects the engine against troubles, damage and interruption, and prevents deterioration of exhaust gases.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes a pre-stored standard relation between an air-fuel ratio sensor signal and a standard air-fuel ratio indicative value for deriving the standard air-fuel ratio indicative value based on the sensor signal. The system further utilizes a pre-stored modified relationship between the standard air-fuel ratio indicative value and a for-control air-fuel ratio indicative value for deriving a for-control air-fuel ratio indicative value based on the derived standard air-fuel ratio indicative value. In the modified relationship, the for-control air-fuel ratio indicative value varies with respect to a corresponding variation of the standard air-fuel ratio indicative value within a given range across the standard air-fuel ratio indicative value representing a stoichiometric air-fuel ratio.

Abstract: Flow passage lines are used to connect the float chamber of a conventional carburetor both to the engine's intake manifold and to a tube positioned downstream of the radiator fan. The air flow produced by the fan provides a continuous source of positive pressure to the float chamber, while the engine's suction and the corresponding vacuum in the intake manifold provide a continuous source of negative pressure. The flow in the positive pressure line and in the negative pressure line is regulated by means of two control solenoid valve. The two valves operate cyclically and off-phase, so that when the pressure valve is closed the vacuum valve is open, and vice versa. The pressure in the float chamber reflects the net impact of the positive and negative pressures transmitted through the lines. The solenoid valves are responsive to a control signal generated by an electronic circuit as a function of deviations in the oxygen content of the exhaust gases from a desired set point.

Abstract: The invention is directed to a method for determining the particular current value of at least one control parameter for a lambda control of an internal combustion engine which provides a shift to make the fuel mixture lean or a shift to make the fuel mixture rich in dependence upon the operating state of the controlled engine. The method includes the steps of: determining a base value for the control parameter in dependence upon the current value of at least one pregiven operating variable as the current value applies for a control with a minimal discharge of toxic gas during steady-state operation of the engine; and, modifying the base value with a transition variable having a value decaying as a function of time when changes in the operating state of the engine occur.

Abstract: In special operating mode, such as, for example, warming up, acceleration, full load, the setting of the mixture is, as is known, performed by a control instead of a .lambda. adjustment. This can result in a lean mixture. This is avoided by the fact that the .lambda. adjustment remains switched on with a restricted range of adjustment during the special operating mode. It is superimposed on the pilot control and only acts in the direction of enrichment.

Abstract: An electronic fuel injection system operable as a bolt on retro fit replacement for a wide variety of carburetors is disclosed. The system includes a throttle body-injector assembly which, by means of an adapter may be bolted directly to stock intake manifolds using the carburetor mounting bolt holes in the manifold. The throttle body passages and injectors are designed to meet the fuel and air delivery requirements of large displacement engines and an electronic control unit which controls the solenoid actuated injectors in a duty cycle operation is provided with externally accessible adjustments by means of which the system may be adjusted to tune the rate of fuel injection to the fuel delivery requirements of engines of displacements much smaller than the largest displacement engine within the systems capability.

Abstract: An air-fuel ratio control system for an internal combustion engine controls the air-fuel ratio of a mixture supplied to the engine to a desired air-fuel ratio in response to an output from an exhaust gas ingredient concentration sensor. A first value of the desired air-fuel ratio is calculated based on the rotational speed of the engine and the load on the engine. A second value of the desired air-fuel ratio is calculated based results of determination on whether a vehicle on which the engine is installed has just started from a standing position thereof. A third value of the desired air-fuel ratio is calculated based on results of determination on whether the temperature of the engine is lower than a predetermined value. The largest value of at least the first to third values of the desired air-fuel ratio is set to a final value of the desired air-fuel ratio.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine which is equipped with an air-fuel ratio sensor for sensing an actual air-fuel ratio of a mixture to be introduced into the engine and a target air-fuel ratio setting section for setting a target air-fuel ratio of the engine. Also included is a controlled-amount calculating section for setting an optimal feedback gain on the basis of a predetermined dynamic model of the engine to calculate a controlled amount in accordance with the predetermined optimal feedback gain so that the actual air-fuel ratio becomes equal to the target air-fuel ratio. A fuel supply amount to the engine is determined on the basis of the calculated controlled amount, and the control responsiveness of the controlled-amount calculating section is suppressed when the engine is in a speed-decreasing state. This arrangement can adequately control the air-fuel ratio of the engine irrespective of the engine speed-decreasing state.

Abstract: An air-fuel ratio control device including an O.sub.2 sensor arranged in the exhaust passage downstream of a three-way catalyst. In the lean air-fuel ratio operating state such as at a fuel cut, when a large amount of oxygen is introduced to the three-way catalyst, air-fuel ratio feedback control by the O.sub.2 sensor output is stopped. Next, after the end of the lean air-fuel ratio operating state, the resumption of the air-fuel ratio feedback control by the O.sub.2 sensor output is delayed for a predetermined time T and, during the delay period, the air-fuel ratio upstream of the catalyst is made rich.

Abstract: An air-fuel ratio feedback control method for an internal combustion engine having an exhaust gas ingredient concentration sensor arranged in the exhaust passage and having output characteristics in approximate proportion to the concentration of an ingredient in exhaust gases from the engine, wherein when the engine is in a predetermined operating condition, the air-fuel ratio of an air-fuel mixture supplied to the engine is feedback-controlled to a desired air-fuel ratio dependent on the predetermined operating condition of the engine, and when the engine is in a predetermined deceleration condition, the fuel supply to the engine is cut off.

Abstract: In an air-fuel ratio control method and apparatus for an internal combustion engine supplied with a gas mixture of air and fuel, in which an actual air-fuel ratio is determined from exhaust gas components by using an O.sub.2 -sensor installed in an exhaust pipe of the engine, and the air-fuel ratio of the mixture gas to be supplied to the engine is controlled through feedback control on the basis of deviation of the actually detected air-fuel ratio from a reference value (A/F=14.7). Performance of the O.sub.2 -sensor is determined by making use of change in the air-fuel ratio output of the O.sub.2 -sensor at a time of interruption of the fuel supply to the engine or at a time the fuel supply to the engine is restarted.

Abstract: Disclosed is an air-fuel ratio control apparatus in an internal combustion engine using different kinds of fuels, such as gasoline and an alcohol, interchangeably or together in a mixed state, wherein at the stationary driving, the integration constant for setting the air-fuel ratio feedback correction coefficient at the air-fuel feedback control is set according to the concentration of the basic fuel such as the alcohol, and at the transient driving, the integration constant is set at a value larger than the value set at the stationary driving. If this structure is adopted, the deflection of the air-fuel ratio at the stationary driving is kept constant irrespectively of the fuel concentration and high exhaust gas-purging performances can be maintained, and at the transient driving, a good response characteristic can be maintained to control excessive thickening or thinning of the air-fuel ratio, and good transient driving performances and high exhaust gas-purging performances can be maintained.

Abstract: An air-fuel ratio control method for an internal combustion engine, in which the air-fuel ratio of a mixture supplied to the engine is feedback-controlled to a desired air-fuel ratio in response to output from an exhaust gas ingredient concentration sensor. When the engine is in a predetermined decelerating condition, fuel supply to the engine is cut off. The rate of correction of the air-fuel ratio of the mixture by the feedback control is set to a larger value before a predetermined time period elapses after the engine shifted from the predetermined decelerating condition to another operating condition, than values to be set after the predetermined time period has elapsed.

Abstract: An air-fuel ratio control method for an internal combustion engine, in which the air-fuel ratio of a mixture supplied to the engine is feedback-controlled to a desired air-fuel ratio in response to output from an exhaust gas ingredient concentration sensor. When the engine is in a predetermined accelerating condition, fuel supply to the engine is increased. The rate of correction of the air-fuel ratio of the mixture by the feedback control is set to a smaller value when the engine is in the predetermined accelerating condition, than values to be set when the engine is in other operating conditions.

Abstract: An internal combustion engine includes a feedback control system for effecting feedback control in order to enrich the air-fuel ratio during acceleration. A distinction device is provided for distinguishing the fuel in use by the internal combustion engine, and includes a control arrangement which distinguishes that the fuel in use is heavy gravity fuel when feedback signals sequentially produced by the feedback control system indicate that the air-fuel ratio has remained lean for at least a predetermined time after acceleration has been attempted.

Abstract: A petrol injection system for an internal combustion engine, the system being adapted to provide additional petrol into the inlet manifold of the engine during acceleration conditions in order to compensate for the less efficient transference of vaporized fuel to the engine cylinders during acceleration conditions, the quantity of additional fuel (BA) being determined in accordance with a stored enrichment value (FBAAM) which is adjusted regularly to take into account changing engine conditions. During the warming-up phase of the engine when the normal lambda regulation is inactive, the magnitude and direction of adjustment of the acceleration enrichment value (FBAAM) is derived from the behavior of the rotational speed (n) of the engine and the .lambda. probe signal (.lambda.>1 or .lambda.<1) during an acceleration enrichment operation in that if, during an acceleration enrichment operation in the warming-up phase of the engine, it is detected that the .lambda.