Abstract: A microcomputer of an alcohol concentration sensor reads a first measurement value corresponding to a first frequency and reads a second measurement value corresponding to a second frequency. The microcomputer calculates a difference between the first and second measurement values. The microcomputer performs stuck failure abnormality determination when a state where the difference between the measurement values is equal to or smaller than a predetermined value continues. The microcomputer outputs a PWM signal of a specific frequency, which is different from a frequency in a case of a normality, to an engine ECU. Thus, a failure of the alcohol concentration sensor can be surely determined.

Abstract: An alcohol concentration sensor detects an alcohol concentration in fuel that is supplied to an internal combustion engine. A fuel injection quantity is controlled in accordance with a detection value of the alcohol concentration that is detected by the alcohol concentration sensor. When a temperature of the fuel, which is detected by a fuel temperature sensor or estimated from intake air temperature etc., is equal to or lower than a predetermined limit temperature, the detection value of the alcohol concentration, which is detected by the alcohol concentration sensor, is memorized as a memorized value of the alcohol concentration. When the temperature of the fuel is higher than the predetermined limit temperature, the fuel injection quantity is controlled by using the memorized value of the alcohol concentration instead of using the detection value, which is currently detected by the alcohol concentration sensor.

Abstract: A capacitance sensing section senses a capacitance between first and second electrodes. A temperature sensing section senses fuel temperature. A microcomputer functions as a concentration sensing section and senses a concentration of ethanol contained in fuel based on the capacitance sensed by the capacitance sensing section and the temperature sensed by the temperature sensing section. The microcomputer functions as an abnormality detecting section and performs abnormality determination to determine that an abnormality has occurred in the capacitance sensing section when the capacitance sensed by the capacitance sensing section does not change and the temperature sensed by the temperature sensing section changes. Since a dielectric constant has such a temperature characteristic that the dielectric constant changes with the temperature, the abnormality detecting section can detect occurrence of the abnormality in the capacitance sensing section.

Abstract: A fuel supply control apparatus for an engine includes an alcohol concentration detector and an engine temperature detector. The apparatus increases an amount of fuel supplied to the engine as the detected alcohol concentration becomes higher. The apparatus increases the amount of fuel as the engine temperature becomes lower and as the alcohol concentration becomes higher. The apparatus feed-back corrects the amount of fuel by using a correction value such that an actual air-fuel ratio becomes a theoretical air fuel ratio. The apparatus determines that water is mixed with fuel when the correction value during a cold operational state indicates leaner than the lean value of the correction value used during a warm operational state. The apparatus reduces the increased amount of fuel when water is mixed with fuel.

Abstract: A capacitance sensing section senses a capacitance between first and second electrodes. A temperature sensing section senses fuel temperature. A microcomputer functions as a concentration sensing section and senses a concentration of ethanol contained in fuel based on the capacitance sensed by the capacitance sensing section and the temperature sensed by the temperature sensing section. The microcomputer functions as an abnormality detecting section and performs abnormality determination to determine that an abnormality has occurred in the capacitance sensing section when the capacitance sensed by the capacitance sensing section does not change and the temperature sensed by the temperature sensing section changes. Since a dielectric constant has such a temperature characteristic that the dielectric constant changes with the temperature, the abnormality detecting section can detect occurrence of the abnormality in the capacitance sensing section.

Abstract: A microcomputer of an alcohol concentration sensor reads a first measurement value corresponding to a first frequency and reads a second measurement value corresponding to a second frequency. The microcomputer calculates a difference between the first and second measurement values. The microcomputer performs stuck failure abnormality determination when a state where the difference between the measurement values is equal to or smaller than a predetermined value continues. The microcomputer outputs a PWM signal of a specific frequency, which is different from a frequency in a case of a normality, to an engine ECU. Thus, a failure of the alcohol concentration sensor can be surely determined.

Abstract: When either one of two injectors of each cylinder becomes abnormal, a control device performs failsafe control of performing increase correction of injection quantity of a normal injector. If actual injection quantity is restricted with the maximum injection quantity that can be injected by the normal injector during the execution of the failsafe control, the control device restricts duty of an actuator of an intake air quantity adjustment mechanism (such as a throttle opening degree), thereby restricting intake air quantity to intake air quantity that does not cause melting damage of a catalyst. Thus, increase of deviation of an air-fuel ratio toward a lean side can be inhibited, and the melting damage of the catalyst can be prevented.

Abstract: A fuel supply control apparatus for an engine includes an alcohol concentration detector and an engine temperature detector. The apparatus increases an amount of fuel supplied to the engine as the detected alcohol concentration becomes higher. The apparatus increases the amount of fuel as the engine temperature becomes lower and as the alcohol concentration becomes higher. The apparatus feed-back corrects the amount of fuel by using a correction value such that an actual air-fuel ratio becomes a theoretical air fuel ratio. The apparatus determines that water is mixed with fuel when the correction value during a cold operational state indicates leaner than the lean value of the correction value used during a warm operational state. The apparatus reduces the increased amount of fuel when water is mixed with fuel.

Abstract: An alcohol concentration sensor detects an alcohol concentration in fuel that is supplied to an internal combustion engine. A fuel injection quantity is controlled in accordance with a detection value of the alcohol concentration that is detected by the alcohol concentration sensor. When a temperature of the fuel, which is detected by a fuel temperature sensor or estimated from intake air temperature etc., is equal to or lower than a predetermined limit temperature, the detection value of the alcohol concentration, which is detected by the alcohol concentration sensor, is memorized as a memorized value of the alcohol concentration. When the temperature of the fuel is higher than the predetermined limit temperature, the fuel injection quantity is controlled by using the memorized value of the alcohol concentration instead of using the detection value, which is currently detected by the alcohol concentration sensor.

Abstract: When either one of two injectors of each cylinder becomes abnormal, a control device performs failsafe control of performing increase correction of injection quantity of a normal injector. If actual injection quantity is restricted with the maximum injection quantity that can be injected by the normal injector during the execution of the failsafe control, the control device restricts duty of an actuator of an intake air quantity adjustment mechanism (such as a throttle opening degree), thereby restricting intake air quantity to intake air quantity that does not cause melting damage of a catalyst. Thus, increase of deviation of an air-fuel ratio toward a lean side can be inhibited, and the melting damage of the catalyst can be prevented.

Abstract: A controller for an internal combustion engine is disclosed that includes an intake control valve adjusting a flow of intake air in the internal combustion engine and controls a position of the intake control valve in accordance with an engine operating condition. The controller includes an in-cylinder pressure detector for detecting an in-cylinder pressure in the internal combustion engine. The controller also includes a gravity position calculator for calculating a gravity position of a total heat generation amount during a combustion period based upon the detected in-cylinder pressure. Additionally, the controller includes an opening correcting unit for correcting a position of the intake control valve based upon the calculated gravity position of the total heat generation amount. A process for controlling the intake control valve is also disclosed.

Abstract: A fuel vapor treatment system is disclosed for a vehicle engine having a leak check device. When a leak is not detected by the leak check device and when a leak is detected but it is determined by a reliability determining device that fuel status determined by a second fuel status determining device is reliable, an air-fuel ratio controlling device switches which to use, a fuel status determined by a first fuel status determining device or a fuel status determined by the second fuel status determining device, based on the operating state of the vehicle. Also, when it is determined by the reliability determining device that the fuel status determined by the second fuel status determining device is unreliable, the air-fuel ratio controlling device uses the fuel status determined by the first fuel status determining device for the fuel status for controlling injection quantity regardless of vehicle operating state.

Abstract: A fuel vapor treatment apparatus includes a first determiner that determines a concentration of purged fuel based on an amount of deviation from a target air-fuel ratio of an air-fuel ratio detected by a sensor provided in an exhaust pipe. A second determiner that determines the concentration of purged fuel in a state in which a purge control valve is closed. Air-fuel ratio controller controls a fuel injection quantity to bring an air-fuel ratio to the target air-fuel ratio on the basis of the concentration of the purged fuel. The air-fuel ratio controller uses the concentration of fuel determined by the second determiner when purge is started or restarted, and uses the concentration of fuel determined by the first determiner thereafter in the course of performing purge. It is possible to increase a purge ratio when purge is started or restarted.

Abstract: A first fuel state determination section determines a fuel condition purged from a canister based on a quantity of deviations from a target air fuel ratio of the measured air-fuel-ratio. A second fuel state determination section determines a fuel condition after a purge control valve has closed. An abnormality detecting section detects an abnormalities of the second fuel state determination section. An air-fuel-ratio learning section performs air-fuel-ratio learning. An air-fuel-ratio-control section controls a fuel injection quantity based on the fuel condition. An initiation timing of the purge by a purge control valve is adjusted based on a history of an abnormality detection of the second fuel state determination section and a learning history of the air-fuel-ratio learning section. A fuel vapor treatment apparatus which can enlarge a purge amount enough is provided.

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: A controller for an internal combustion engine is disclosed that includes an intake control valve adjusting a flow of intake air in the internal combustion engine and controls a position of the intake control valve in accordance with an engine operating condition. The controller includes an in-cylinder pressure detector for detecting an in-cylinder pressure in the internal combustion engine. The controller also includes a gravity position calculator for calculating a gravity position of a total heat generation amount during a combustion period based upon the detected in-cylinder pressure. Additionally, the controller includes an opening correcting unit for correcting a position of the intake control valve based upon the calculated gravity position of the total heat generation amount. A process for controlling the intake control valve is also disclosed.

Abstract: A fuel vapor treatment system is disclosed for a vehicle engine having a leak check device. When a leak is not detected by the leak check device and when a leak is detected but it is determined by a reliability determining device that fuel status determined by a second fuel status determining device is reliable, an air-fuel ratio controlling device switches which to use, a fuel status determined by a first fuel status determining device or a fuel status determined by the second fuel status determining device, based on the operating state of the vehicle. Also, when it is determined by the reliability determining device that the fuel status determined by the second fuel status determining device is unreliable, the air-fuel ratio controlling device uses the fuel status determined by the first fuel status determining device for the fuel status for controlling injection quantity regardless of vehicle operating state.

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: A fuel vapor treatment apparatus includes a first determiner that determines a concentration of purged fuel based on an amount of deviation from a target air-fuel ratio of an air-fuel ratio detected by a sensor provided in an exhaust pipe. A second determiner that determines the concentration of purged fuel in a state in which a purge control valve is closed. Air-fuel ratio controller controls a fuel injection quantity to bring an air-fuel ratio to the target air-fuel ratio on the basis of the concentration of the purged fuel. The air-fuel ratio controller uses the concentration of fuel determined by the second determiner when purge is started or restarted, and uses the concentration of fuel determined by the first determiner thereafter in the course of performing purge. It is possible to increase a purge ratio when purge is started or restarted.

Abstract: During a learning mode period, the fuel correction coefficient is forcibly changed three times from a situation in which no correction is necessary, whereby the fuel injection quantity of each cylinder is forcibly changed three times. A cross-correlation between the estimated air-fuel ratio and the fuel correction coefficient, which are calculated based on the detected value of the air-fuel ratio sensor every 60° CA, is evaluated to learn a deviation of the air-fuel ratio detecting timing from the appropriate value.