Abstract: An exhaust gas purifying apparatus for an internal combustion engine having a particulate filter provided in an exhaust system of the engine. Regeneration control is performed of burning particulates accumulated in the particulate filter. An oxygen concentration in exhaust gases flowing into the particulate filter is detected, and a flow rate of oxygen flowing into the particulate filter is calculated according to the detected oxygen concentration. An inflowing oxygen amount is calculated by integrating the oxygen flow rate when performing regeneration control. It is determined that an abnormality has occurred if the inflowing oxygen amount at a time when regeneration control ends is equal to or less than a predetermined amount.

Abstract: A particulate filter is provided in an exhaust system of the engine. Parameter values correlated with a flow amount of exhaust gas of the engine are determined, and differential pressure between upstream and downstream sides of the particulate filter is determined. The ratio of a variation rate of the parameter values correlated with the exhaust flow amount to a variation rate of the differential pressure is compared with a predetermined threshold value during transitional operation of the engine to determine the state of the particulate filter.

Abstract: Deterioration of a catalyst provided in an exhaust system of the engine is determined. Air-fuel ratio sensors are provided in the upstream side and the downstream side of the catalyst. Air-fuel ratio is changed. Based on the sensor outputs in the upstream die and the downstream side of the catalyst, a parameter of a catalyst model representing a state of the catalyst is identified. The parameter is compared with a threshold to determine a state of the catalyst.

Abstract: An exhaust gas purifying apparatus for an internal combustion engine having a particulate filter provided in an exhaust system of the engine. Regeneration control is performed of burning particulates accumulated in the particulate filter. An oxygen concentration in exhaust gases flowing into the particulate filter is detected, and a flow rate of oxygen flowing into the particulate filter is calculated according to the detected oxygen concentration. An inflowing oxygen amount is calculated by integrating the oxygen flow rate when performing regeneration control. It is determined that an abnormality has occurred if the inflowing oxygen amount at a time when regeneration control ends is equal to or less than a predetermined amount.

Abstract: An abnormality determination apparatus and method for a blow-by gas feedback device, and an engine control unit are provided for improving the accuracy of abnormality determination even when an intake air amount controller is provided in an intake system at a location downstream of a joint of a blow-by gas passage. The blow-by gas feedback device feeds a blow-by gas back to an intake system of an internal combustion engine through a blow-by gas passage connected to the intake system through a joint.

Abstract: A failure determination system for determining failures of temperature sensors, which is capable of easily and accurately determining failures of the sensors in actual operating temperature ranges thereof, even when the ranges are different from each other. Temperatures detected by exhaust gas temperature sensors are stored as initial temperatures when the engine has stopped. Temperatures detected by the respective sensors after stoppage of the engine are made dimensionless based on the corresponding initial temperatures to thereby calculate dimensionless values. An estimated dimensionless value of a temperature to be detected when each sensor is normal is set in advance as an estimated normal value. Failures of the sensors are determined based on results of comparisons of the dimensionless values with the estimated normal value.

Abstract: An abnormality determination apparatus and method for a blow-by gas feedback device, and an engine control unit are provided for improving the accuracy of abnormality determination even when an intake air amount controller is provided in an intake system at a location downstream of a joint of a blow-by gas passage. The blow-by gas feedback device feeds a blow-by gas back to an intake system of an internal combustion engine through a blow-by gas passage connected to the intake system through a joint.

Abstract: An apparatus for detecting a failure of a thermostat provided between an engine and a radiator is provided. The thermostat regulates circulation of cooling water between the engine and the radiator. The apparatus comprises a radiator water temperature sensor disposed on the radiator side relative to the thermostat and a controller. The controller performs a process for detecting a failure of the thermostat based on the output of the radiator water temperature sensor when the engine has reached a desired warm condition. In one example, it is determined whether the engine has reached the desired warm condition based on the output of the engine water temperature sensor that is provided in the engine side relative to the thermostat. In another example, it is determined whether the engine had reached the desired warm condition according to whether a vehicle-related process is activated.

Abstract: A particulate filter is provided in an exhaust system of the engine. Parameter values correlated with a flow amount of exhaust gas of the engine are determined, and differential pressure between upstream and downstream sides of the particulate filter is determined. The ratio of a variation rate of the parameter values correlated with the exhaust flow amount to a variation rate of the differential pressure is compared with a predetermined threshold value during transitional operation of the engine to determine the state of the particulate filter.

Abstract: Deterioration of a catalyst provided in an exhaust system of the engine is determined. Air-fuel ratio sensors are provided in the upstream side and the downstream side of the catalyst. Air-fuel ratio is changed. Based on the sensor outputs in the upstream die and the downstream side of the catalyst, a parameter of a catalyst model representing a state of the catalyst is identified. The parameter is compared with a threshold to determine a state of the catalyst.

Abstract: A failure determination system for determining failures of temperature sensors, which is capable of easily and accurately determining failures of the sensors in actual operating temperature ranges thereof, even when the ranges are different from each other. Temperatures detected by exhaust gas temperature sensors are stored as initial temperatures when the engine has stopped. Temperatures detected by the respective sensors after stoppage of the engine are made dimensionless based on the corresponding initial temperatures to thereby calculate dimensionless values. An estimated dimensionless value of a temperature to be detected when each sensor is normal is set in advance as an estimated normal value. Failures of the sensors are determined based on results of comparisons of the dimensionless values with the estimated normal value.

Abstract: In a malfunction detecting system of an engine cooling apparatus constituted as a radiator having a thermostat opening/closing an inlet pipe and an outlet pipe, a temperature sensor is installed at the radiator to detect a temperature of the coolant flowing through the radiator. In the system, a period of time since the engine starting is measured and is compared with a predetermined value indicative of a period of time until the thermostat presumably opens. Then, the detected coolant temperature is compared with three reference values, when the measured period of time exceeds the predetermined value and it is discriminated that the cooling apparatus, more specifically, the thermostat of the radiator has malfunctioned, when the coolant temperature exceeds a medium one of the reference values. In addition, it is discriminated the apparatus has malfunctioned, if the coolant temperature exceeds the highest reference value, even when the measured period of time does not exceed the predetermined value.

Abstract: An apparatus for determining leakage in an evaporated fuel processing system is provided. The evaporated fuel processing system extends from a fuel tank through a canister to a purge passage through which evaporated fuel from the fuel tank is purged to an intake manifold of an engine. The canister comprises a vent-shut valve that communicates with the atmosphere. The apparatus comprises a pressure sensor for detecting a pressure of the evaporated fuel processing system and a control unit connected to the pressure sensor. The control unit detects a stop of the engine. After the stop of the engine is detected, the control unit closes the vent-shut valve to close the evaporated fuel processing system. The control unit determines whether the evaporated fuel processing system has leakage after the evaporated fuel processing system is closed based on the detected pressure and a predetermined determination value.

Abstract: An apparatus for determining leakage in an evaporated fuel processing system is provided. The evaporated fuel processing system extends from a fuel tank to a purge passage through which evaporated fuel from the fuel tank is purged to an intake manifold of an engine. The apparatus comprises a pressure sensor for detecting a pressure of the evaporated fuel processing system, an atmospheric pressure sensor for detecting an atmospheric pressure, and a control unit connected to the pressure sensor and the atmospheric pressure sensor. The control unit detects a stop of the engine. A determination value used for the leakage determination is corrected according to the atmospheric pressure. The evaporated fuel processing system is closed after the stop of the engine is detected. It is determined whether the evaporated fuel processing system has leakage based on the pressure detected by the pressure sensor and the corrected determination value.

Abstract: The invention provides a failure diagnosing apparatus having a first sensor for detecting a temperature of cooling water of an engine mounted on a vehicle and a second sensor for detecting a temperature associated with the engine. The apparatus calculates a first difference between a temperature detected by the first sensor at the time when the engine stops in a previous operating cycle and a temperature detected by the first sensor at the time when the engine starts in a current operating cycle is calculated. The apparatus also calculates a second difference between a temperature detected by the second sensor at the time when the engine stops in the previous operating cycle and a temperature detected by the second sensor at the time when the engine starts in the current operating cycle. It is determined whether the first sensor is faulty based on the first difference and the second difference.

Abstract: In a malfunction detecting system of an engine cooling apparatus constituted as a radiator having a thermostat that opens/closes a communicating passage between the engine and the radiator, estimated coolant temperature is calculated using a thermal load parameter correlated to rise in the coolant temperature after engine starting, whilst an engine standing time period is detected. Then, the detected engine standing time period is compared with a predetermined value and based on a result of comparison, one of preset threshold values including a malfunction discrimination threshold value and a malfunction discrimination execute threshold value is selected.

Abstract: An apparatus for detecting a failure of a thermostat provided between an engine and a radiator is provided. The thermostat regulates circulation of cooling water between the engine and the radiator. The apparatus comprises a radiator water temperature sensor disposed on the radiator side relative to the thermostat and a controller. The controller performs a process for detecting a failure of the thermostat based on the output of the radiator water temperature sensor when the engine has reached a desired warm condition. In one example, it is determined whether the engine has reached the desired warm condition based on the output of the engine water temperature sensor that is provided in the engine side relative to the thermostat. In another example, it is determined whether the engine had reached the desired warm condition according to whether a vehicle-related process is activated.

Abstract: The invention provides a failure diagnosing apparatus having a first sensor for detecting a temperature of cooling water of an engine mounted on a vehicle and a second sensor for detecting a temperature associated with the engine. The apparatus calculates a first difference between a temperature detected by the first sensor at the time when the engine stops in a previous operating cycle and a temperature detected by the first sensor at the time when the engine starts in a current operating cycle is calculated. The apparatus also calculates a second difference between a temperature detected by the second sensor at the time when the engine stops in the previous operating cycle and a temperature detected by the second sensor at the time when the engine starts in the current operating cycle. It is determined whether the first sensor is faulty based on the first difference and the second difference.

Abstract: In a malfunction detecting system of an engine cooling apparatus constituted as a radiator having a thermostat that opens/closes a communicating passage between the engine and the radiator, estimated coolant temperature is calculated using a thermal load parameter correlated to rise in the coolant temperature after engine starting, whilst an engine standing time period is detected. Then, the detected engine standing time period is compared with a predetermined value and based on a result of comparison, one of preset threshold values including a malfunction discrimination threshold value and a malfunction discrimination execute threshold value is selected.

Abstract: In a malfunction detecting system of an engine cooling apparatus constituted as a radiator having a thermostat opening/closing an inlet pipe and an outlet pipe, a temperature sensor is installed at the radiator to detect a temperature of the coolant flowing through the radiator. In the system, a period of time since the engine starting is measured and is compared with a predetermined value indicative of a period of time until the thermostat presumably opens. Then, the detected coolant temperature is compared with three reference values, when the measured period of time exceeds the predetermined value and it is discriminated that the cooling apparatus, more specifically, the thermostat of the radiator has malfunctioned, when the coolant temperature exceeds a medium one of the reference values. In addition, it is discriminated the apparatus has malfunctioned, if the coolant temperature exceeds the highest reference value, even when the measured period of time does not exceed the predetermined value.