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 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: A misfire detector calculates the engine speed fluctuation quantity &Dgr;&ohgr;n for a predetermined period of time on the basis of the average engine speed on, which is the reciprocal of the time T120n that the crankshaft of the engine takes to turn 120 degrees. By comparing the calculated engine speed fluctuation quantity &Dgr;&ohgr;n with a misfire determination value REF, from which it can be determined whether the engine is misfiring, the misfire detector determines whether the engine is misfiring. The misfire detector detects the rotational fluctuation per combustion stroke of each engine cylinder and learns the variation of the detected rotational fluctuation values during normal combustion. From this learned value and the detected rotational fluctuation value per combustion stroke of the cylinder, the misfire detector determines whether the cylinder is misfiring or not.

Abstract: A misfire detection apparatus for an internal combustion engine determines misfire based on first and second variation amounts calculated based on variations of rotational speed of the internal combustion engine. A second variation amount is calculated, and it is determined whether or not a value obtained by multiplying the second variation amount by −1 is greater than a misfire determination level C1, and if the value is less than the level, process proceeds calculates a final variation amount. If the value is greater than a predetermined value, the process determines the final variation amount from the first variation amount. When the processing has been completed, the process determines whether or not the final variation amount is equal to or greater than the misfire determination level.

Abstract: An apparatus for detecting a condition of the burning in an internal combustion engine includes a burning-parameter controlling device for controlling a burning parameter operating on the burning in the internal combustion engine. A burning-condition detecting device operates for, in cases where the burning parameter is changed by the burning-parameter controlling device, sampling prescribed information for detecting a burning condition.

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: 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 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 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 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: An apparatus for detecting a condition of the burning in an internal combustion engine includes a burning-parameter controlling device for controlling a burning parameter operating on the burning in the internal combustion engine. A burning-condition detecting device operates for, in cases where the burning parameter is changed by the burning-parameter controlling device, sampling prescribed information for detecting a burning condition.

Abstract: A misfire detection apparatus for an internal combustion engine determines misfire based on first and second variation amounts calculated based on variations of rotational speed of the internal combustion engine. A second variation amount is calculated, and it is determined whether or not a value obtained by multiplying the second variation amount by −1 is greater than a misfire determination level C1, and if the value is less than the level, process proceeds calculates a final variation amount. If the value is greater than a predetermined value, the process determines the final variation amount from the first variation amount. When the processing has been completed, the process determines whether or not the final variation amount is equal to or greater than the misfire determination level.

Abstract: A blow-by gas passage abnormality detecting system for an internal combustion engine detects, only under the condition that the running state of the engine is idle, a leakage of a blow-by gas coming from a blow-by gas passage for returning the blow-by gas produced in the engine to an intake passage, on the basis of a parameter varying with a change in the air flow to be sucked into the engine. The abnormality such as leakage or clogging in the blow-by gas passage is detected if the ISC opening of an idle speed control valve measured as a load amount at an idle time of the engine is smaller than a predetermined value. Alternatively, the abnormality may be detected by detecting the blow-by gas pressure in the blow-by gas passage downstream of a PCV valve by a gas pressure sensor.

Abstract: A blow-by gas passage abnormality detecting system for an internal combustion engine detects, only under the condition that the running state of the engine is idle, a leakage of a blow-by gas coming from a blow-by gas passage for returning the blow-by gas produced in the engine to an intake passage, on the basis of a parameter varying with a change in the air flow to be sucked into the engine. The abnormality such as leakage or clogging in the blow-by gas passage is detected if the ISC opening of an idle speed control valve measured as a load amount at an idle time of the engine is smaller than a predetermined value. Alternatively, the abnormality may be detected by detecting the blow-by gas pressure in the blow-by gas passage downstream of a PCV valve by a gas pressure sensor.

Abstract: A blow-by gas passage abnormality detecting system for an internal combustion engine detects, only under the condition that the running state of the engine is idle, a leakage of a blow-by gas coming from a blow-by gas passage for returning the blow-by gas produced in the engine to an intake passage, on the basis of a parameter varying with a change in the air flow to be sucked into the engine. The abnormality such as leakage or clogging in the blow-by gas passage is detected if the ISC opening of an idle speed control valve measured as a load amount at an idle time of the engine is smaller than a predetermined value. Alternatively, the abnormality may be detected by detecting the blow-by gas pressure in the blow-by gas passage downstream of a PCV valve by a gas pressure sensor.

Abstract: A blow-by gas passage abnormality detecting system for an internal combustion engine detects, only under the condition that the running state of the engine is idle, a leakage of a blow-by gas coming from a blow-by gas passage for returning the blow-by gas produced in the engine to an intake passage, on the basis of a parameter varying with a change in the air flow to be sucked into the engine. The abnormality such as leakage or clogging in the blow-by gas passage is detected if the ISC opening of an idle speed control valve measured as a load amount at an idle time of the engine is smaller than a predetermined value. Alternatively, the abnormality may be detected by detecting the blow-by gas pressure in the blow-by gas passage downstream of a PCV valve by a gas pressure sensor.

Abstract: A fuel property, i.e., ordinary fuel, heavy fuel or mixture of both, is determined using an engine rotations. After an engine temperature exceeds 0.degree. C. and an engine attains a complete combustion, an engine speed is integrated. It is determined whether a deviation between the integrated value of the engine speed and an integrated value of a set engine speed is larger than a predetermined determination value. As a result, it can be determined whether the fuel fed to the internal combustion engine has a volatility identical to that of the ordinary fuel, so that the fuel properties can be highly accurately determined.

Abstract: An open/close means M1 opens or closes an EGR passage. An engine load detecting means M2 detects an engine load, such as an intake air amount or an intake air pressure. Either an open. condition or a closed condition of the open/close means M1 is specified as a referential state, while the other is specified as a non-referential state. A memory means M3 memorizes engine loads at the referential state and the non-referential state. A constant acceleration judging means M4 makes a judgement as to whether or not the operational condition of the engine is in a constant accelerating condition. An open/close control means M5 switches the open/close means M1 from the referential state to the non-referential state in response to a constant accelerating condition detected by the constant acceleration judging means M4.