Abstract: An intake air quantity information determining arrangement senses or computes one of an intake air quantity and a torque of an internal combustion engine as intake air quantity information. A misfire-avoidance control arrangement executes a misfire-avoidance control operation, which avoids misfire by controlling a throttle opening degree of a throttle valve such that a value of the intake air quantity information does not decrease below a normal combustion threshold value.

Abstract: An intake air quantity information determining arrangement senses or computes one of an intake air quantity and a torque of an internal combustion engine as intake air quantity information. A misfire-avoidance control arrangement executes a misfire-avoidance control operation, which avoids misfire by controlling a throttle opening degree of a throttle valve such that a value of the intake air quantity information does not decrease below a normal combustion threshold value.

Abstract: A fuel pressure varies according to whether a fuel pressure sensor and a high-pressure pump have a malfunction or not. In view of this, a first threshold Perr1 is defined for determining whether the fuel pressure sensor has a malfunction and a second threshold Perr2 is defined for determining whether the high-pressure pump has a malfunction. The second threshold Perr2 is greater than the first threshold Perr1. By comparing a detection value of the fuel pressure sensor with the first and the second threshold, a malfunction in the fuel pressure sensor and a malfunction in the high-pressure pump are distinguished from each other. A first fail-safe control or a second fail-safe control is executed according to a portion having a malfunction.

Abstract: A cylinder-inflow EGR gas amount is estimated, a misfire limit EGR gas amount is calculated on the basis of an engine operation state, and the misfire limit EGR gas amount is compared with the cylinder-inflow EGR gas amount to predict whether a misfire occurs. When the misfire is predicted, a misfire avoidance control is executed. Further, an actual misfire countermeasure effect amount in a case of the execution of the misfire avoidance control is calculated, and the actual misfire countermeasure effect amount is compared with a required misfire countermeasure effect amount to determine whether the misfire is avoidable when the misfire avoidance control is executed. If the misfire is unavoidable even if the misfire avoidance control is executed, a delay restriction value of an ignition timing to avoid the misfire is calculated, and the amount of a delay in the ignition timing is restricted using the delay restriction value.

Abstract: When a given learning performance condition is met, a partial lift injection for opening a fuel injector is performed by an injection pulse which brings about a partial lift state in which a lift quantity of a valve body of the fuel injector does not reach a full lift position, and an integrated value of a drive current is calculated which flows through a drive coil of the fuel injector after an injection pulse of the partial lift injection is turned off. An inductance of the drive coil is calculated in consideration of a direct current superposition characteristic of the drive coil on the basis of the integrated value of the drive current, whereby the inductance of the drive coil is calculated with high accuracy. Then, the lift quantity of the valve body is estimated on the basis of the inductance, whereby the lift quantity of the valve body is estimated with high accuracy.

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 a constant driving voltage is applied to a motor driving an EGR valve so that the EGR opening degree is varied, an angular speed of the EGR valve becomes minimal at a position where the driving torque of the EGR valve becomes maximal. In view of this, while an opening degree of the EGR valve is varied with a constant driving voltage applied to the motor, the EGR opening degree where the angular speed becomes minimal is learned as a full-close position.

Abstract: While an engine is an idling state and an EGR opening degree is increased stepwise from a specified opening degree, a variation in engine speed (a standard deviation in engine speed) is repeatedly computed. After that, a specified step amount is successively reduced from the EGR opening degree and the variation in engine speed is successively computed until the EGR opening degree becomes less than or equal to a specified value. Then, a maximum value of the EGR opening degrees where the variation in engine speed becomes minimum is learned as the full-close position.

Abstract: An intake air quantity information determining arrangement senses or computes one of an intake air quantity and a torque of an internal combustion engine as intake air quantity information. A misfire-avoidance control arrangement executes a misfire-avoidance control operation, which avoids misfire by controlling a throttle opening degree of a throttle valve such that a value of the intake air quantity information does not decrease below a normal combustion threshold value.

Abstract: A cylinder-inflow EGR gas quantity determining arrangement estimates or senses a value of a cylinder-inflow EGR gas quantity, which is a quantity of EGR gas that flows into a cylinder of an internal combustion engine. A misfire predicting arrangement predicts whether misfire occurs based on the value of the cylinder-inflow EGR gas quantity and an operational state of the internal combustion engine. A misfire-avoidance control arrangement executes at least one misfire-avoidance control operation to avoid the misfire when the misfire predicting arrangement predicts that the misfire occurs.

Abstract: In an EGR system, a quantity of exhaust gas passing through an EGR valve is computed by an EGR valve model simulating a behavior of the recirculated exhaust gas passing through the EGR valve. An exhaust gas quantity flowing into a cylinder is computed by an EGR-gas-delay model simulating a behavior of the exhaust gas passing through the EGR valve and the throttle valve and then flows into a cylinder. The EGR-gas-delay model includes a confluent-delay model simulating a behavior of EGR gas passing thorough the EGR valve and flowing into the intake passage upstream of the throttle valve; an intake-pipe-delay model simulating a behavior of EGR gas flowing in the intake passage and passing through the throttle valve; and an intake-manifold-delay model simulating a behavior of EGR gas which passes through the throttle valve and then flows into the intake passage downstream of the throttle valve.

Abstract: EGR gas quantity information, which indicates a quantity of the EGR gas flowing into a cylinder of an internal combustion engine, is obtained by an ECU. A combustion stop delay control operation, which delays execution of a combustion stop control operation, is executed by the ECU when the quantity of the EGR gas flowing into the cylinder is larger than a normal combustion determination threshold value. When the quantity of the EGR gas flowing into the cylinder becomes equal to or smaller than the normal combustion determination threshold value, the combustion stop control operation is enabled by the ECU.

Abstract: A fuel diluting quantity is estimated based on an alcohol concentration of the fuel. A response-deterioration determination value is corrected according to the estimated fuel diluting quantity. The response-deterioration determination value can be properly established even though the responsiveness of the variable valve timing controller is varied due to a variation in viscosity of the lubricant. Thereby, even when the responsiveness of the variable valve timing controller is varied (deteriorated) due to an increase in the fuel diluting quantity, it can be avoided that the computer determines that the variable valve timing controller has a defect.

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 pressure varies according to whether a fuel pressure sensor and a high-pressure pump have a malfunction or not. In view of this, a first threshold Perr1 is defined for determining whether the fuel pressure sensor has a malfunction and a second threshold Perr2 is defined for determining whether the high-pressure pump has a malfunction. The second threshold Perr2 is greater than the first threshold Perr1. By comparing a detection value of the fuel pressure sensor with the first and the second threshold, a malfunction in the fuel pressure sensor and a malfunction in the high-pressure pump are distinguished from each other. A first fail-safe control or a second fail-safe control is executed according to a portion having a malfunction.

Abstract: A fuel injection control device for an engine executes a split injection constructed by a fixed injection and a variable injection. A required injection amount of the fixed injection is set in a low range. A required injection amount of the variable injection is set in a high range. An injection amount in the high range is larger than that of the low range. The required injection amount of the variable injection is changed within the high range while the required injection amount of the fixed injection is fixed when a load of the engine is varied while the split injection is performed. An injection control characteristic is corrected based on an actual air-fuel ratio detected before the load is varied and an actual air-fuel ratio detected after the load is varied.

Abstract: A fuel diluting quantity is estimated based on an alcohol concentration of the fuel. A response-deterioration determination value is corrected according to the estimated fuel diluting quantity. The response-deterioration determination value can be properly established even though the responsiveness of the variable valve timing controller is varied due to a variation in viscosity of the lubricant. Thereby, even when the responsiveness of the variable valve timing controller is varied (deteriorated) due to an increase in the fuel diluting quantity, it can be avoided that the computer determines that the variable valve timing controller has a defect.

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: 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.