Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. The system includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in the fuel tank, an air passage connected to the canister for communicating the canister with the atmosphere, a first passage for connecting the canister and the fuel tank, a second passage for connecting the canister and an intake system of an internal combustion engine, and a purge control valve provided in the second passage. A pressure in the evaporative fuel processing system is detected. An opening of the purge control valve is controlled by changing a duty ratio of a drive signal which drives the purge control valve. First and second filterings of the detected pressure are performed. A second passing frequency band of the second filtering is narrower than a first passing frequency band of the first filtering.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system wherein a pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves. The determination result is decided according to a parameter indicative of an amount of evaporative fuel generated in the fuel tank after stoppage of the engine.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. The system includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in the fuel tank, an air passage connected to the canister for communicating the canister with the atmosphere, a first passage for connecting the canister and the fuel tank, a second passage for connecting the canister and an intake system of an internal combustion engine, and a purge control valve provided in the second passage. A pressure in the evaporative fuel processing system is detected. An opening of the purge control valve is controlled by changing a duty ratio of a drive signal which drives the purge control valve. First and second filterings of the detected pressure are performed. A second passing frequency band of the second filtering is narrower than a first passing frequency band of the first filtering.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. A pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system wherein a pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves. The determination result is decided according to a parameter indicative of an amount of evaporative fuel generated in the fuel tank after stoppage of the engine.

Abstract: An atmosphere-vented valve (a pressure relief section) is opened in a predetermined amount so as to reduce an inside pressure of a canister to a predetermined negative pressure (S14) while preventing an inside pressure in a fuel tank from becoming an excessively negative pressure by closing a charge passageway opening and closing valve (S18), and purging is controlled while the canister inside pressure is being reduced, whereby from a similar principle to that of vacuum distillation, the release of vaporized fuel from an absorbent is promoted so as not only to increase the purge efficiency but also to prevent the application of an unnecessary stress to the fuel tank.

Abstract: A deviation DGAIR between a first induction air volume GAIRTH that is calculated (S10) based on a detected value (Gair) of an air flow meter and a second induction air volume GAIRPB that is calculated (S12) based on an absolute pressure (PBA) is calculated (S14), and a mean value DGAIRAVE of the deviation DGAIR is calculated (S16, S18), whereby when a difference DDGAIR between the deviation DGAIR and the mean value DGAIRAVE is larger than a predetermined value DGAIL1 (or when a correction mode AFMMODE is 1), secondary air is determined to be supplied to an engine, and the first induction air volume GAIRTH is then corrected (S24, S26).

Abstract: A fault determining apparatus for a variable valve timing mechanism is provided for shortly and accurately determining a fault even at low oil temperatures. The mechanism is driven by an oil pressure to change a cam phase of an intake cam and/or an exhaust cam with respect to a crank shaft of an internal combustion engine, thereby controlling the actual cam phase to reach a target cam phase. The apparatus has a fault determining routine executed by an ECU (electric control unit) for determining that the mechanism is faulty when a cam phase difference between the target cam phase and the actual cam phase is not within a predetermined range, an oil temperature sensor for detecting the temperature of the working oil, and a correcting routine executed by the ECU for correcting the predetermined range in an increasing direction when the detected oil temperature is low.

Abstract: An evaporative fuel processing system for processing evaporative fuel generated a fuel tank. A canister temporarily stores evaporative fuel generated in the fuel tank. A charge passage connects the fuel tank and the canister. A first purge passage connects the canister and an intake pipe of an internal combustion engine having a turbocharger. A purge control valve is provided in the first purge passage for adjusting a flow rate of gases flowing through the first purge passage. A second purge passage connects a downstream side of the purge control valve of the first purge passage and an upstream side of the turbocharger of the intake pipe. A jet pump is mounted on the second purge passage. A pressurized air supply passage supplies air pressurized by the turbocharger to the jet pump. The jet pump includes a nozzle for discharging the pressurized air supplied through the pressurized air supply passage.

Abstract: An evaporative fuel processing system for processing evaporative fuel generated a fuel tank. A canister temporarily stores evaporative fuel generated in the fuel tank. A charge passage connects the fuel tank and the canister. A first purge passage connects the canister and an intake pipe of an internal combustion engine having a turbocharger. A purge control valve is provided in the first purge passage for adjusting a flow rate of gases flowing through the first purge passage. A second purge passage connects a downstream side of the purge control valve of the first purge passage and an upstream side of the turbocharger of the intake pipe. A jet pump is mounted on the second purge passage. A pressurized air supply passage supplies air pressurized by the turbocharger to the jet pump. The jet pump includes a nozzle for discharging the pressurized air supplied through the pressurized air supply passage.

Abstract: An atmosphere-vented valve (a pressure relief section) is opened in a predetermined amount so as to reduce an inside pressure of a canister to a predetermined negative pressure (S14) while preventing an inside pressure in a fuel tank from becoming an excessively negative pressure by closing a charge passageway opening and closing valve (S18), and purging is controlled while the canister inside pressure is being reduced, whereby from a similar principle to that of vacuum distillation, the release of vaporized fuel from an absorbent is promoted so as not only to increase the purge efficiency but also to prevent the application of an unnecessary stress to the fuel tank.

Abstract: A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. A pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves.

Abstract: A deviation DGAIR between a first induction air volume GAIRTH that is calculated (S10) based on a detected value (Gair) of an air flow meter and a second induction air volume GAIRPB that is calculated (S12) based on an absolute pressure (PBA) is calculated (S14), and a mean value DGAIRAVE of the deviation DGAIR is calculated (S16, S18), whereby when a difference DDGAIR between the deviation DGAIR and the mean value DGAIRAVE is larger than a predetermined value DGAIL1 (or when a correction mode AFMMODE is 1), secondary air is determined to be supplied to an engine, and the first induction air volume GAIRTH is then corrected (S24, S26).

Abstract: There is provided a failure determination apparatus which is capable of determining the failure of a temperature sensor promptly and correctly regardless of environmental conditions at the start of an internal combustion engine. An ECU calculates an operation progress parameter indicative of a degree of progress of operation of the internal combustion engine from the start thereof. A RAM of the ECU stores a value of the temperature detected by the temperature sensor at a stoppage of the engine.

Abstract: There is provided a valve timing control system for an internal combustion engine, which is capable of properly controlling valve timing while maintaining the accuracy of degradation determination of an oxygen concentration sensor or an exhaust gas-purifying device. The valve timing control system for an internal combustion engine includes a degradation-determining system that performs degradation determination of at least one of the oxygen concentration sensor and the exhaust gas-purifying device in a state in which the air-fuel ratio of a mixture supplied to the engine is controlled to a predetermined state, and controls valve timing by changing the cam phase. An ECU determines whether or not executing conditions for the degradation determination by the degradation-determining system are satisfied.

Abstract: There is provided a valve timing control system for an internal combustion engine, which is capable of properly controlling valve timing while maintaining the accuracy of degradation determination of an oxygen concentration sensor or an exhaust gas-purifying device. The valve timing control system for an internal combustion engine includes a degradation-determining system that performs degradation determination of at least one of the oxygen concentration sensor and the exhaust gas-purifying device in a state in which the air-fuel ratio of a mixture supplied to the engine is controlled to a predetermined state, and controls valve timing by changing the cam phase. An ECU determines whether or not executing conditions for the degradation determination by the degradation-determining system are satisfied.

Abstract: There is provided a failure determination apparatus which is capable of determining the failure of a temperature sensor promptly and correctly regardless of environmental conditions at the start of an internal combustion engine. An ECU calculates an operation progress parameter indicative of a degree of progress of operation of the internal combustion engine from the start thereof. A RAM of the ECU stores a value of the temperature detected by the temperature sensor at a stoppage of the engine.

Abstract: A fault determining apparatus for a variable valve timing mechanism is provided for shortly and accurately making a fault determination while preventing an erroneous determination even at low oil temperatures. The variable valve timing mechanism is driven by an oil pressure of a working oil to change a cam phase of an intake cam and/or an exhaust cam with respect to a crank shaft of an internal combustion engine to change an opening/closing timing of the intake valve and/or exhaust valve, and to control the actual cam phase in a feedback manner to reach a set target cam phase.

Abstract: A controller for an internal combustion engine has a hydraulic valve characteristic changing mechanism for changing valve operating characteristics of suction and exhaust valves; a valve system provided with a hydraulic valve phase variable mechanism that changes the phase; a map that stores a fuel injection quantity and an ignition timing in response to the valve operating characteristics; and delay time setting means for setting a delay time required to complete changeover of the valve operating characteristics, based on operating oil properties detected from behavior of a valve phase variable mechanism, to change the map after the delay time has elapsed. Thus, a valve operating characteristic changing timing coincides with a map changing timing to thereby achieve an improved performance of the internal combustion engine.

Abstract: In a valve lift control system for engine intake valves which selectively changes an intake valve lift of an engine, and a phase angle relationship of a timing of opening the engine valve in relation with a crankshaft angle depending on the operating condition of the engine, an arrangement is made to limit the advancing of the opening timing of the engine valve when a large valve lift is selected. It is thus possible to limit the advancing of the timing of opening the engine intake valve only when the valve lift is increased, and the advancing of the timing of opening the engine intake valve may cause an interference between the engine intake valve and the corresponding engine piston. The valve opening timing is otherwise optimized, and the maximum performance of the engine can be attained under all possible circumstances.