Abstract: In an exhaust secondary air supply system including an electric air pump and a flow rate control valve disposed in an air supply passage connected to an exhaust passage of an engine, the electric air pump is first driven after the start of the engine, and the flow rate control valve is then opened after a lapse of a predetermined time. At a time after starting the driving of the electric air pump, the abnormality of the electric air pump is detected by comparing a deviation between the current before and after driving of the electric air pump with a predetermined reference value. After opening of the flow rate control valve, the abnormality of the flow rate control valve is detected by comparing the deviation between the current before and after the opening of the flow rate control valve with a predetermined reference value.

Abstract: A control system for an internal combustion engine has a catalyst arranged in the exhaust system, for purifying exhaust gases emitted from the engine. An ECU controls operation of the engine, based on at least one predetermined control parameter, and detects a temperature state of the catalyst at the start of the engine. The at least one predetermined control parameter is changed, based on the detected temperature state of the catalyst, after the start of the engine.

Abstract: An exhaust gas-purifying device for an internal combustion engine has an adsorbing device arranged in an exhaust passage of the engine for adsorbing unburnt fuel components in exhaust gases from the engine, a catalytic converter arranged in same at a location downstream of the adsorbing device for purifying the exhaust gases, and a heater for electrically heating the catalytic converter. The temperature of the adsorbing device is detected. The heater is controlled to be operated at least on condition that the temperature of the adsorbing device is above a predetermined value. In another form of the invention, the temperature of the catalytic converter is detected. A rate of a rise of the temperature of the catalytic converter is determined. A deterioration state of the adsorbing device is determined based on the rate of the rise of the temperature of the catalytic converter.

Abstract: An exhaust gas-purifying device for an internal combustion engine has an adsorbing device arranged in an exhaust passage of the engine for adsorbing unburnt fuel components in exhaust gases from the engine, a catalytic converter arranged in same at a location downstream of the adsorbing device for purifying the exhaust gases, and a heater for electrically heating the catalytic converter. The temperature of the adsorbing device is detected. The heater is controlled to be operated at least on condition that the temperature of the adsorbing device is above a predetermined value. In another form of the invention, the temperature of the catalytic converter is detected. A rate of a rise of the temperature of the catalytic converter is determined. A deterioration state of the adsorbing device is determined based on the rate of the rise of the temperature of the catalytic converter.

Abstract: An exhaust gas-purifying system for an internal combustion engine includes a catalyzer arranged in the exhaust system of the engine. The catalyzer is provided with a heater for heating the same. An ECU controls the operation of the heater. The ECU is responsive to operating conditions of the engine detected by engine operating parameter sensors, for restraining the operation of the heater.

Abstract: An adsorber temperature-estimating device for an internal combustion engine comprises an adsorber arranged in the exhaust passage, for adsorbing an unburnt gas component present in exhaust gases emitted from the engine. Operating parameter sensors detect operating parameters of the engine, and an ECU estimates the temperature of the adsorber, based on the detected operating parameters. An exhaust gas-purifying system for the engine comprises the adsorber, a catalytic converter arranged in the exhaust passage at a location downstream of the adsorbing means, for purifying exhaust gases, and a secondary air supply pump for supplying secondary air to the exhaust passage at a location upstream of the catalytic converter. The ECU controls an amount of secondary air to be supplied to the exhaust passage, based on the estimated temperature calculated by the adsorber temperature-estimating device.

Abstract: An adsorbing capacity determining apparatus is provided for determining the adsorbing capacity of an unburned component adsorbing device in an exhaust system for an internal combustion engine. The adsorbing capacity determining apparatus comprises upstream and downstream air-fuel ratio detectors, respectively coupled upstream and downstream from the unburned component adsorbing device, a temperature sensor for sensing the temperature of the unburned component adsorbing means and a computer for determining the adsorption capacity as a function of the outputs of the system and downstream air-fuel ratio detectors, when the temperature is within a predetermined range.

Abstract: An exhaust gas-purifying system for an internal combustion engine has an adsorbing device arranged in an exhaust passage thereof for adsorbing or desorbing unburnt component contained in exhaust gases. An exhaust gas recirculation passage branches off from the exhaust passage at a branch point downstream of the adsorbing device and extending to an intake passage of the engine for returning exhaust gases flowing through the adsorbing device to the intake passage. The path of exhaust gases is changed to selectively introduce the exhaust gases containing the unburnt components into the exhaust gas recirculation passage. The adsorbing capacity of the adsorbing device is checked based on a manner of change in an air-fuel ratio of exhaust gases detected when the exhaust gases are introduced into the exhaust gas recirculation passage.

Abstract: In a multi-cylinder internal combustion engine including a plurality of fuel injection valves corresponding to a plurality of cylinders, respectively, and a catalytic converter provided in an exhaust system common to the cylinders, the concentration of oxygen in the exhaust gas from the engine is precisely controlled in accordance with the operational condition of the engine in a low-temperature state of the engine for the prompt activation of the catalyst. When the engine is at a low temperature, the operation of the fuel injection valves is controlled so as to stop the supplying of a fuel into the particular cylinders and, the operation of a valve operating characteristic changing means is controlled to adjust the amounts of air drawn and discharged on the basis of conditions detected by operational condition detecting means and at such low temperature to thereby control the oxygen supplied to the catalyst in the catalytic converter whereby the activity of the catalyst can be controlled.

Abstract: An internal combustion engine has an adsorber arranged in the exhaust passage for adsorbing unburnt components in exhaust gases, and an exhaust gas-purifying device arranged in the exhaust passage at a location downstream of the adsorber. The exhaust gas-purifying device is equipped with a heater. An ignition timing of an internal combustion engine is retarded when the engine is started at a low engine temperature. The retardation of the ignition timing is restrained over a time period from the start of the engine to a time point the exhaust gas-purifying device is warmed up to a predetermined activated condition.

Abstract: In an engine exhaust emission control system, a ternary catalyst and a hydrocarbon adsorber are provided in an exhaust passageway from an engine. The ternary catalyst includes first passages through which an exhaust gas discharged from the engine flows, and second passages through which the exhaust gas which has flowed through the first passages and the hydrocarbon adsorber flows. The first and second passages are laminated to each other to enable heat exchange therebetween. The hydrocarbon adsorber is capable of being cooled by a cooling medium. Thus, it is possible to reliably prevent hydrocarbons in the exhaust gas from being released to the atmosphere during the cold start of the engine.

Abstract: An exhaust gas-purging system for an internal combustion engine includes a catalyst arranged in an exhaust passage of the engine, for purifying exhaust gases emitted from the engine. The system detects an engine operating condition and a catalyst temperature parameter indicative of the temperature of the catalyst. The supply of secondary air to the exhaust passage and the flow path cross-sectional area of the exhaust passage are controlled based on at least one of the operating condition of the engine and the catalyst temperature parameter.

Abstract: An exhaust gas-purifying system for an internal combustion engine is provided with hydrocarbon-adsorbing catalyzer for adsorbing unburnt gas components present in exhaust gases. At least one exhaust gas-purifying catalyzer is arranged in the exhaust passage at a location downstream of the hydrocarbon-adsorbing catalyzer. A bypass passage bypasses the hydrocarbon-purifying catalyzer. A changeover valve is arranged in the exhaust passage at a branchpoint between the bypass passage and the exhaust passage, for selecting a first flow path in which exhaust gases are guided to the unburnt gas component-adsorbing catalyzer, or a second flow path in which exhaust gases are guided through the bypass passage. First and second exhaust gas concentration sensors are arranged in the exhaust passage at locations upstream and downstream of the hydrocarbon-purifying catalyzer.

Abstract: In an air-fuel ratio control system for an internal combustion engine, an output from a first air-fuel ratio sensor arranged upstream of a three-way catalyst mounted across an exhaust passage of the engine is compared with a reference value during feedback control of the air-fuel ratio. The reference value is controlled based on an output from a second air-fuel ratio sensor arranged downstream of the three-way catalyst. The reference value is changed in dependence on the engine load detected.

Abstract: A catalytic converter heater control system for an internal combustion engine comprising a catalytic converter installed in the engine exhaust gas passage and having a small capacity section on its upstream side and a large capacity section on its downstream side. The system has a pair of oxygen sensors installed one on the upstream side and one on the downstream side of the catalytic converter, a heater installed on the small capacity reaction section for heating incoming exhaust gas, and an electronic control unit for operating the heater when the difference between the outputs of the oxygen sensors is smaller than a prescribed value.

Abstract: A mass flowmeter outputs an output value indicative of the flow rate of a gaseous mixture containing evaporative fuel and being purged into the intake system of an internal combustion engine. A calculated value of the flow rate of the mixture is obtained based on a plurality of operating parameters of the engine. The actual flow rate of the mixture and/or the actual flow rate of the evaporative fuel are/is calculated based on the output value from the mass flowmeter and the calculated value based on the engine operating parameters. The concentration of the evaporative fuel is calculated from the calculated actual flow rates of the evaporative fuel and the mixture. The calculated actual flow rate is compared with a desired flow rate value, and a purge control valve is controlled based on results of the comparison. A basic amount of fuel supplied to the engine is corrected based on the calculated actual flow rate of the evaporative fuel.

Abstract: A catalyst temperature control system is provided for an internal combustion engine having a catalyst arranged in the exhaust system for purifying noxious components in exhaust gases emitted from the engine, and an exhaust gas recirculation passage connected to the intake system and the exhaust system for returning part of the exhaust gases from the exhaust system to the intake system. The temperature of a catalyst bed of the catalyst is detected. An ECU increases a recirculation amount of exhaust gases flowing through the exhaust gas recirculation passage, when the detected temperature of the catalyst bed is higher than a first predetermined value, and enriches the air-fuel ratio of a mixture supplied to the engine. when the detected temperature of the catalyst bed is higher than a second predetermined value upon the lapse of a predetermined time period after the start of increase of the recirculation amount.

Abstract: A method of detecting abnormality in a fuel supply system of an internal combustion engine. An amount of fuel supplied to the engine is controlled in a feedback manner based on an air-fuel ratio correction coefficient set in response to an output signal from at least one exhaust gas component concentration sensor. The method comprises the steps of (1) calculating an abnormality determination value based on the air-fuel ratio correction coefficient, (2) calculating a learned average value of the air-fuel ratio correction coefficient, (3) renewing the abnormality determination value when the calculated learned average value of the air-fuel ratio correction coefficient falls outside a first predetermined range defined based upon the abnormality determination coefficient, and (4) determining that the fuel supply system is abnormal when the renewed value of the abnormality determination value falls outside a second predetermined range defined by predetermined upper and lower limit values.