Abstract: It is an object of the present invention to provide a controlling apparatus for throttle valve that detects a throttle open degree enabling more appropriate controls by removing ill effects of multiplexing an idle control in controlling data. The idle control amount is canceled by subtracting the idle target open degree from the detected throttle open degree. Further, in order to correct differences of the detected data due to a response delay of the throttle valve, the previous measured value is regarded as the detected throttle open degree when the response delay occurs.

Abstract: An air-fuel ratio control apparatus constructed, in an engine of a type storing evaporated fuel generated in a fuel tank in a canister and thereafter drawing off the evaporated fuel to an intake side of an engine through a bleedoff passage, so as to inhibit renewal of an air-fuel ratio learning value when the evaporated fuel concentration is at a predetermined value or higher in case of learning and renewal of an air-fuel ratio in order to make feedback control of the air-fuel ratio of an air-fuel mixture supplied to the engine. In an apparatus which adsorbs evaporated fuel generated in a fuel tank in a canister and purges the evaporated fuel adsorbed in the canister to an intake side of an internal combustion engine together with air through a purge valve, an air-fuel ratio learning value is renewed in accordance with a deviation between an air-fuel ratio feedback FAF value detected by an oxygen sensor and a FAFSM value obtained by smoothing the FAF value with a large smoothing constant.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine for learning and controlling an air-fuel ratio accurately even during execution of purging of evaporated fuel. The evaporated fuel generated in a fuel tank is adsorbed to a canister, and the adsorbed fuel is evaporated and purged together with air to the intake side of the internal combustion engine through a purge valve. During normal purge rate control by the purge valve, air-fuel ratio feedback values detected by an oxygen sensor are averaged, and the concentration of the evaporated fuel taken into the internal combustion engine through the purge valve is detected by the deviation from a stoichiometric air-fuel ratio 1 of the averaged value and the purge rate. Further, after the lapse of a predetermined period of time after purging is started, air-fuel ratio learning values are renewed in accordance with the air-fuel ratio feedback value and stored in a RAM.

Abstract: Disclosed is an apparatus for detecting deterioration of a catalyst of an internal combustion engine having a plurality of cylinder banks in such a manner that the deterioration of the catalyst can be assuredly discriminated regardless of the presence of deviation of a control phase with respect to each cylinder bank. The influence of change of the air/fuel ratio can be eliminated considerably by reducing the air/fuel ratio correction coefficient for a right bank, or by also using the correction coefficient for the left bank as that for the right bank to cause the phases of them to be synchronized with each other, or by dither-controlling the right bank. Therefore, the change of the air/fuel ratio with respect to the left bank can be assuredly detected while necessitating one sub air/fuel ratio sensor.

Abstract: In engine control apparatus with exhaust gas recirculation control and air/fuel ratio feedback control, the amount of recirculated exhausted gasses is accurately detected so as to operate an internal combustion engine under an optimal operating condition all the time. To this end a correction factor derived from oxygen sensor output, which is used for air/fuel ratio control, is monitored to obtain a difference of a correction factor value resulted from engine operation with EGR and another correction factor value resulted from engine operation with EGR. This difference is obtained by forcibly interrupting EGR operation. Once the amount of recirculated exhaust is accurately estimated, the EGR control and/or air/fuel ratio control are performed with compensation for possible error due to secular change in EGR system.

Abstract: A method and an apparatus for controlling the air-fuel ratio in an internal combustion engine in which the calculation of the presumed amount of fuel attached to the wall of the intake port of the engine is effected for correcting the amount of the fuel supplied to the engine in order to compensate for the variation of the air-fuel ratio of the air-fuel mixture used in the combustion of the engine.

Abstract: A closed loop mixture control system for internal combustion engines is responsive to a signal derived from an exhaust gas sensor. The sensor signal is time-integrated in a direction depending on the level of the gas sensor output to derive a first mixture corrective setting of the control system. Second corrective settings or learning data are established for the control system in correspondence with the amount of air supplied to the engine. Each of the latter settings is varied as a function of time in a direction depending on the value of the time-varying first corrective setting relative to a reference so that the second settings are automatically updated to meet varying engine performance such as aging. One of the second corrective settings is selected in response to the detected quantity of the supplied air and multiplied by the first corrective setting to correct the basic mixture control setting of the system toward an optimum value.

Abstract: In a feedback control system for air/fuel ratio control of an internal combustion engine, an integration correcting amount is derived from the output signal of a gas sensor indicative of the concentration of an exhaust gas component, and an engine condition correcting amount is selected from a memory in which a plurality of engine condition correcting amounts are prestored in the form of a map. The engine condition correcting amount is renewed in accordance with the variation in the value of the integration correcting amount only within a given period of time or within an interval corresponding to a given number of rotations of the engine crankshaft from an instant of detection of the variation of the gas sensor output level. Thus, the engine condition correcting amount is renewed only when the output signal level of the gas sensor is reliable.