Abstract: An abnormality detection device of an internal combustion engine includes an ECU that is an abnormality detection unit detecting a leakage occurrence of a second pure pipe. When the internal combustion engine is in a supercharging operation state that a supercharger operates and the second purge pipe is closed by a second purge valve, the ECU detects the leakage occurrence of the second purge pipe based on a differential pressure between a pressure in the second purge pipe and an atmospheric pressure. In this case, the valve pressure in the second purge pipe is a pressure in the second purge pipe between the second purge valve and the intake pipe.

Abstract: An abnormality detection device of an internal combustion engine includes an ECU that is an abnormality detection unit detecting a leakage occurrence of a second pure pipe. When the internal combustion engine is in a supercharging operation state that a supercharger operates and the second purge pipe is closed by a second purge valve, the ECU detects the leakage occurrence of the second purge pipe based on a differential pressure between a pressure in the second purge pipe and an atmospheric pressure. In this case, the valve pressure in the second purge pipe is a pressure in the second purge pipe between the second purge valve and the intake pipe.

Abstract: A leakage diagnosis apparatus is applied to an evaporated-gas purge system including a negative-pressure sensor and a pressure detecting portion. The negative-pressure sensor introduces a negative pressure into an evaporation system. The pressure detecting portion detects the pressure in the evaporation system. The leakage diagnosis apparatus includes a leakage-diagnosis portion and a determining portion. The leakage-diagnosis portion executes a leakage diagnosis to determine whether a leakage of the evaporation system is generated. The determining portion determines whether an evaporated-gas amount in the evaporation system is in an excessive state while the internal combustion engine is stopped. The leakage-diagnosis portion prohibits or terminates the leakage diagnosis, when the determining portion determines that the evaporated-gas amount is in the excessive state.

Abstract: A leakage diagnosis apparatus is applied to an evaporated-gas purge system including a negative-pressure sensor and a pressure detecting portion. The negative-pressure sensor introduces a negative pressure into an evaporation system. The pressure detecting portion detects the pressure in the evaporation system. The leakage diagnosis apparatus includes a leakage-diagnosis portion and a determining portion. The leakage-diagnosis portion executes a leakage diagnosis to determine whether a leakage of the evaporation system is generated. The determining portion determines whether an evaporated-gas amount in the evaporation system is in an excessive state while the internal combustion engine is stopped. The leakage-diagnosis portion prohibits or terminates the leakage diagnosis, when the determining portion determines that the evaporated-gas amount is in the excessive state.

Abstract: A pressure sensor senses a pressure of a fuel vapor system at a fuel vapor passage. An electronic control unit executes a post-depressurization period flow diagnosis to determine whether the fuel vapor passage is clogged based on a behavior of the pressure in the fuel vapor system, which is sensed with the pressure sensor in a sealed state of the fuel vapor system after introduction of a negative pressure into the fuel vapor system.

Abstract: A cylinder deviation of an actual air-fuel ratio before an air-fuel-ratio dither control is obtained based on a variation of an actual air-fuel ratio by the dither control, a variation amount of detected air-fuel ratio, and a cylinder deviation of detected air-fuel ratio before the dither control. A cylinder deviation of actual air-fuel ratio of each cylinder is accurately estimated. When the number of times in which the cylinder deviation of air-fuel ratio exceeds a decision value is greater than a predetermined number, it is determined that an abnormality occurs in the cylinder.

Abstract: A pressure sensor senses a pressure of a fuel vapor system at a fuel vapor passage. An electronic control unit executes a post-depressurization period flow diagnosis to determine whether the fuel vapor passage is clogged based on a behavior of the pressure in the fuel vapor system, which is sensed with the pressure sensor in a sealed state of the fuel vapor system after introduction of a negative pressure into the fuel vapor system.

Abstract: There is provided an air-fuel ratio control apparatus of an internal combustion engine capable of learning an air-fuel ratio and performing purge at the same time. When purge is being performed, in an air-fuel ratio learning routine, an air-fuel ratio deviation between an air-fuel ratio detected by an air-fuel ratio sensor and a target air-fuel ratio is computed by the use of a fuel vapor concentration detected in a concentration detection routine and then a learning correction value flaf to correct the computed air-fuel ratio deviation is computed.

Abstract: A diagnosis device calculates a lean-direction responsiveness characteristic and a rich-direction responsiveness characteristic of the exhaust gas sensor. The lean-direction responsiveness represents a responsiveness of the sensor in a case that an air-fuel ratio is controlled in such a manner as to be varied in a lean direction. The rich-direction responsiveness represents a responsiveness of the sensor in a case that the air-fuel ratio is controlled in such a manner as to be varied in a rich direction. The diagnosis device determines whether the exhaust gas sensor deteriorates based on at least one of the lean-direction responsiveness characteristic and the rich-direction responsiveness characteristic, and on a comparison result between the lean-direction responsiveness characteristic and the rich-direction responsiveness characteristic.

Abstract: A cylinder deviation of an actual air-fuel ratio before an air-fuel-ratio dither control is obtained based on a variation of an actual air-fuel ratio by the dither control, a variation amount of detected air-fuel ratio, and a cylinder deviation of detected air-fuel ratio before the dither control A cylinder deviation of actual air-fuel ratio of each cylinder is accurately estimated. When the number of times in which the cylinder deviation of air-fuel ratio exceeds a decision value is greater than a predetermined number, it is determined that an abnormality occurs in the cylinder.

Abstract: In an evaporated fuel treatment system, a pump is operated to flow air through a specified restriction and a sensor detects a first differential pressure across the restriction. A fuel tank, a canister, and the restriction are made to communicate with each other and an air-fuel mixture containing the evaporated fuel is purged from the canister. The mixture flows through the restriction and a second differential pressure across the restriction is detected. A differential pressure ratio and an evaporated fuel concentration used for the control of a flow rate are computed from these differential pressures. When fuel swings in a period during which the second differential pressure is detected, the pressure difference ratio is not computed and the flowrate control of the air-fuel mixture is not conducted.

Abstract: There is provided an air-fuel ratio control apparatus of an internal combustion engine capable of learning an air-fuel ratio and performing purge at the same time. When purge is being performed, in an air-fuel ratio learning routine, an air-fuel ratio deviation between an air-fuel ratio detected by an air-fuel ratio sensor and a target air-fuel ratio is computed by the use of a fuel vapor concentration detected in a concentration detection routine and then a learning correction value flaf to correct the computed air-fuel ratio deviation is computed.

Abstract: A diagnosis device calculates a lean-direction responsiveness characteristic and a rich-direction responsiveness characteristic of the exhaust gas sensor. The lean-direction responsiveness represents a responsiveness of the sensor in a case that an air-fuel ratio is controlled in such a manner as to be varied in a lean direction. The rich-direction responsiveness represents a responsiveness of the sensor in a case that the air-fuel ratio is controlled in such a manner as to be varied in a rich direction. The diagnosis device determines whether the exhaust gas sensor deteriorates based on at least one of the lean-direction responsiveness characteristic and the rich-direction responsiveness characteristic, and on a comparison result between the lean-direction responsiveness characteristic and the rich-direction responsiveness characteristic.

Abstract: In an evaporated fuel treatment system, a pump is operated to flow air through a specified restriction and a sensor detects a first differential pressure across the restriction. A fuel tank, a canister, and the restriction are made to communicate with each other and an air-fuel mixture containing the evaporated fuel is purged from the canister. The mixture flows through the restriction and a second differential pressure across the restriction is detected. A differential pressure ratio and an evaporated fuel concentration used for the control of a flow rate are computed from these differential pressures. When fuel swings in a period during which the second differential pressure is detected, the pressure difference ratio is not computed and the flowrate control of the air-fuel mixture is not conducted.

Abstract: An engine control system has a self-diagnosis function of an exhaust system. The self-diagnosis function includes a first mode for detecting a failure or abnormality of the exhaust system as a whole, and a second mode for determining and locating a specific failed component in the exhaust system. The first mode is executed during the engine is operated under a normal condition. Therefore it is possible to detect the failure of the exhaust system without lowering a drive performance or increasing emissions. In case of detecting any failure in the first mode, the second mode is activated in response to a command signal that can be entered via a service tool. In the second mode, the engine is operated in order to determine the failed component. In the second mode, determining the failed component takes priority over keeping the drive performance or reducing emissions.

Abstract: A leak check system executes a leak check processing. In the leak check processing, the system closes a canister valve and a purge valve to close the fuel vapor purge system. Then, the system detects and monitors a pressure in the fuel vapor purge system. During the leak check processing, the system detects a rapid change of the pressure that is caused by a deformation of a wall of a fuel tank. The system cancels or suspends the processing to avoid erroneous detection of the leak. If the leak check is canceled, the system opens the canister valve to open the fuel vapor purge system.

Abstract: A fuel-vapor-processing system for an engine has a canister for accumulating fuel evaporation gas. The system has a leak-check apparatus for checking a leak on passages. The leak-check apparatus includes a leak-check means for carrying out leak-check processing when the engine if in a stopped state. The leak-check means operates only if a predetermined condition is satisfied. It is thus possible to reduce the number of times the leak-check processing is carried out and, hence, possible to reduce power consumption. For example, only if a relatively small leak is detected when the engine is in a running state, the leak-check processing is carried out in a stopped state to verify existence of such a leak. In the leak-check processing, the temperature of fuel, detected by a sensor or an estimated value, may be taken into consideration.

Abstract: In a fuel vapor handling system of this invention, an ECU performs a leak check to check a leak of fuel vapor in a fuel vapor passage when the engine is at a stop. The ECU functions to detect the quantity of fuel during the engine stop. The ECU detects the quantity of fuel at the time of engine starting. Furthermore, the ECU compares the quantity of fuel measured at the time of engine starting with the quantity of fuel measured at the preceding engine stop, to thereby determine whether a filler cap was opened during the engine stop. When the filler cap was opened during the engine stop, a result of the leak check will be cancelled. When the filler cap was not opened, the result of the leak check will be determined.

Abstract: A fuel vapor control system has a controller that carries out a leak check processing after the engine is stopped. The controller includes a device that intermittently activates the controller itself or a part of the controller to sample an internal pressure of the fuel vapor passage. Then, after a predetermined time, the controller determines that whether the sampled values of the internal pressure indicate a leak or not by evaluating the sampled values. According to the arrangement, since at least a part of the controller is activated intermittently, the consumption of electricity can be reduced. The fuel vapor control system has a canister valve and a purge valve made of normally close type valves in order to reduce the consumption of electricity after the engine is stopped.

Abstract: A leak check system executes a leak check processing. In the leak check processing, the system closes a canister valve and a purge valve to close the fuel vapor purge system. Then, the system detects and monitors a pressure in the fuel vapor purge system. During the leak check processing, the system detects a rapid change of the pressure that is caused by a deformation of a wall of a fuel tank. The system cancels or suspends the processing to avoid erroneous detection of the leak. If the leak check is canceled, the system opens the canister valve to open the fuel vapor purge system.