Abstract: Control apparatus for an engine includes a failure determination unit which determines whether there is a failure in an operating engine, and an A/F (air-fuel ratio) feedback control unit which performs feedback control to bring actual A/F in the engine to a target set in advance. The failure determination unit includes a failure determination section, a failure code storing section, a similar operating condition recording section, and a return-to-normal control section. The A/F feedback control unit includes an A/F target setting section, and the target set is stored in the similar operating condition recording section as a factor defining the operating condition of the engine. The return-to-normal control section eliminates the failure code if the failure determination section does not determine that there is a failure when the engine is operating in an operating condition similar to that recorded in the similar operating condition recording section.

Abstract: A diagnostic device incorporates a processor and a memory and diagnoses a failure related to a fuel injection system for an engine whose air-fuel ratio of is feedback-controlled. The diagnostic device includes a calculation unit which calculates a corrected value of a fuel injection amount according to a difference between a target value and a measured value of the air-fuel ratio. The diagnostic device includes a setting unit which sets a mask period in which a failure diagnosis is suspended, according to the corrected value upon switchover of a fuel injection mode. The diagnostic device includes a diagnostic unit which does not carry out the diagnosis in the mask period and carries out the diagnosis outside the mask period.

Abstract: A failure detection apparatus for fuel systems of an engine includes a first failure determiner executing, while the engine is in each of a first injection form and a second injection form, a failure determination process on the corresponding fuel system, a second failure determiner executing, when the first failure determiner determines occurrence of a failure in one of the injection forms, a failure determination process on the fuel system corresponding to the other injection form, a failure locator determining whether or not the failure has occurred, for each of the fuel systems responsible for the first and second injection forms, based on a result by the second failure determiner, and a purge process prohibiter prohibiting execution of a purge process for the engine. The second failure determiner causes the purge process prohibiter to prohibit execution of the purge process, when executing the failure determination process on the fuel system.

Abstract: A failure determination apparatus for an oxygen concentration sensor disposed downstream of a catalyst provided in an exhaust system is provided for detecting a failure in the oxygen concentration sensor. The failure determination apparatus comprises: a failure determination device for determining a failure in the oxygen concentration sensor based on the length of a period when the output of the oxygen concentration sensor passes through a predetermined output section during enrichment control after a fuel cut mode of the internal combustion engine is released; a rich fuel supply amount calculation device for calculating the time average of an enriching fuel supply amount, relative to a fuel supply amount necessary for stoichiometric combustion, based on an actual fuel supply amount during the enrichment control; and a failure determination restriction device for restricting failure determination of the failure determination device based on the time average of the enriching fuel supply amount.

Abstract: A failure detection apparatus for fuel systems of an engine includes a first failure determiner executing, while the engine is in each of a first injection form and a second injection form, a failure determination process on the corresponding fuel system, a second failure determiner executing, when the first failure determiner determines occurrence of a failure in one of the injection forms, a failure determination process on the fuel system corresponding to the other injection form, a failure locator determining whether or not the failure has occurred, for each of the fuel systems responsible for the first and second injection forms, based on a result by the second failure determiner, and a purge process prohibiter prohibiting execution of a purge process for the engine. The second failure determiner causes the purge process prohibiter to prohibit execution of the purge process, when executing the failure determination process on the fuel system.

Abstract: A deterioration determination unit determines whether a catalyst in an exhaust passage of an engine is deteriorated; a first determination unit determines whether there is an air-fuel ratio variation among cylinders of the engine on the basis of distortion in waveform of the air-fuel ratio on the upstream side of the catalyst; and a second determination unit determines whether there is an air-fuel ratio variation among the cylinders on the basis that the air-fuel ratio on the downstream side of the catalyst remains on the lean side. A determination mode switching unit makes the first determination unit execute a determination process concurrently with determination by the deterioration determination unit, and it is determined by the determination process that there is an air-fuel ratio variation among the cylinders, makes the second determination unit execute a determination process in priority to determination of deterioration of the catalyst.

Abstract: Control apparatus for an engine includes a failure determination unit which determines whether there is a failure in an operating engine, and an A/F (air-fuel ratio) feedback control unit which performs feedback control to bring actual A/F in the engine to a target set in advance. The failure determination unit includes a failure determination section, a failure code storing section, a similar operating condition recording section, and a return-to-normal control section. The A/F feedback control unit includes an A/F target setting section, and the target set is stored in the similar operating condition recording section as a factor defining the operating condition of the engine. The return-to-normal control section eliminates the failure code if the failure determination section does not determine that there is a failure when the engine is operating in an operating condition similar to that recorded in the similar operating condition recording section.

Abstract: There is provided fuel-system failure detection apparatus applied to an engine capable of switching between a first injection mode and a second injection mode, which comprises a first failure determination unit which performs a fuel system failure determination process while the engine is operating in the first and the second injection modes, respectively, a second failure determination unit which, when the first failure determination unit gives a decision of failure while the engine is operating in either of the two injection modes, performs the fuel system failure determination process while the engine is operating in the other injection mode, and a failure identification unit which identifies a failure in fuel systems governing the first and second injection modes respectively, based on a decision about failure given by the second failure determination unit.

Abstract: A diagnostic device incorporates a processor and a memory and diagnoses a failure related to a fuel injection system for an engine whose air-fuel ratio of is feedback-controlled. The diagnostic device includes a calculation unit which calculates a corrected value of a fuel injection amount according to a difference between a target value and a measured value of the air-fuel ratio. The diagnostic device includes a setting unit which sets a mask period in which a failure diagnosis is suspended, according to the corrected value upon switchover of a fuel injection mode. The diagnostic device includes a diagnostic unit which does not carry out the diagnosis in the mask period and carries out the diagnosis outside the mask period.

Abstract: A first temperature sensor measures a first temperature of an object related to an engine. A fuel temperature sensor measures a fuel temperature. A diagnostic apparatus includes a diagnostic unit diagnosing the first temperature sensor based at least in part on the first temperature measured at the first temperature sensor. The diagnostic apparatus also includes a first determining unit determining whether the state of fault of the first temperature sensor is unclear or not based at least in part on the variation in the fuel temperature after the start-up of the engine for the diagnosis at the diagnostic unit.

Abstract: A first temperature sensor measures a first temperature of an object related to an engine. A fuel temperature sensor measures a fuel temperature. A diagnostic apparatus includes a diagnostic unit diagnosing the first temperature sensor based at least in part on the first temperature measured at the first temperature sensor. The diagnostic apparatus also includes a first determining unit determining whether the state of fault of the first temperature sensor is unclear or not based at least in part on the variation in the fuel temperature after the start-up of the engine for the diagnosis at the diagnostic unit.

Abstract: A failure determination apparatus for an oxygen concentration sensor disposed downstream of a catalyst provided in an exhaust system of an internal combustion engines is provided for detecting a failure in the oxygen concentration sensor with high accuracy while preventing an erroneous determination of the failure.

Abstract: During normal engine operation, a temporary determination mode is executed in which whether or not there is an air-fuel ratio variation among cylinders is determined on the basis of distortion in output waveform of an LAF sensor, concurrently with determination of deterioration of a three-way catalyst, under a control condition of normal learning sensitivity of the learned value of a stoichiometry correction factor. If it is determined in the temporary determination mode that there is an air-fuel ratio variation, the determination mode is switched to a main determination mode and the learning sensitivity of the learned value of the stoichiometry correction factor is set to the sensitive side to determine whether or not there is an air-fuel ratio variation among the cylinders with higher reliability on the basis of the learned value of the stoichiometry correction factor (=the value of an enrichment process counter C2) which increases rapidly due to the air-fuel ratio variation among the cylinders.

Abstract: A control device for an engine includes an air-fuel ratio detector detecting an air-fuel ratio of an exhaust gas of the engine. A feedback controller performs a feedback control of an amount of a fuel injection of mixed fuel including alcohol so that the air-fuel ratio detected by the air-fuel ratio detector is come close to a target air-fuel ratio, the mixed fuel supplied from a fuel feeder. A concentration estimator estimates a concentration of the alcohol in the mixed fuel based on the air-fuel ratio of the exhaust gas and a correction amount for the amount of the fuel injection controlled by the feedback control. A malfunction determiner determines that the fuel feeder has a malfunction when the correction amount is greater than or equal to a value for a period which is longer than a first period in a second period. The second period is from a first time point when the feedback controller starts to perform the feedback control.

Abstract: A control device for an engine includes an air-fuel ratio detector detecting an air-fuel ratio of an exhaust gas of the engine. A feedback controller performs a feedback control of an amount of a fuel injection of mixed fuel including alcohol so that the air-fuel ratio detected by the air-fuel ratio detector is come close to a target air-fuel ratio, the mixed fuel supplied from a fuel feeder. A concentration estimator estimates a concentration of the alcohol in the mixed fuel based on the air-fuel ratio of the exhaust gas and a correction amount for the amount of the fuel injection controlled by the feedback control. A malfunction determiner determines that the fuel feeder has a malfunction when the correction amount is greater than or equal to a value for a period which is longer than a first period in a second period. The second period is from a first time point when the feedback controller starts to perform the feedback control.