Abstract: In variable operation intake valve controlling apparatus and method for an internal combustion engine, using both of a cam operational angle variable mechanism and a cam phase variable mechanism, a controller controls an intake air quantity in accordance with valve timings of the intake valve determined according to the operational angle through the cam operational angle variable mechanism and the phase through the cam phase variable mechanism, the controller determining an allowable residual gas quantity from a required air quantity and an engine speed, the required air quantity being determined according to a manipulated variable of an accelerator, calculating optimum intake valve open and closure timings (IVO and IVC) in such a manner that both of the required air quantity and the allowable residual gas quantity enter a cylinder of the engine, and determining the operational angle and the phase from the optimum intake valve open and closure timings.

Abstract: In a failure diagnosis apparatus of a position control system (variable valve operating system) wherein a target position of a control object (camshaft) changes and an actual position of the control object is feedback-controlled to the target position. A failure of the position control system is detected based upon a difference (&Sgr;C=&Sgr;A−&rgr;B) or a ratio (&Sgr;B/&Sgr;A) between an integral value &Sgr;A of the target position and an integral value &Sgr;B of the actual position thereof.

Abstract: In a variable intake-valve operating system for an engine enabling a working angle of an intake valve and a phase at a maximum lift point of the intake valve to be varied, a variable working-angle control mechanism is provided to continuously change the working angle of the intake valve and a variable phase control mechanism is provided to continuously change the phase of the intake valve. A control unit is configured to be electronically connected to both the two variable control mechanisms, to simultaneously control these control mechanisms responsively to a desired working angle and a desired phase both based on an engine operating condition. The control unit executes a synchronous control that a time rate of change of the working angle and a time rate of change of the phase are synchronized with each other in a transient state that the engine operating condition changes.

Abstract: Oxygen sensors (3, 13) are provided upstream and downstream of a three-way catalytic converter (10) in an exhaust passage (9) of an internal combustion engine (1). A controller (2) performs feedback correction of an air-fuel ratio of an air-fuel mixture burnt in the engine (1) by proportional/integral control based on the output of the upstream oxygen sensor (3). In this process, the controller (2) corrects a proportional part by a correction value based on the output of the downstream oxygen sensor (13) (S11, S12). The feedback correction is performed based on a feedback correction coefficient calculated using the proportional part and an integral part. The controller (2) further determines if there is a leak in the exhaust passage (9) based on the correction value (S61) (S62). Higher diagnostic precision is obtained than in the case where the determination is performed based directly on the feedback correction coefficient.

Abstract: In digital data counterfeit detecting program, apparatus, and method, an address arithmetic processing is performed for a value of one of a plurality of digital data which is stored in each of addresses, a result of the address arithmetic processing performed for the value of the one of the digital data representing one of the addresses and a predetermined arithmetic processing is executed for the value stored in each of the addresses which are the respective results of the address arithmetic processing to calculate a collation value used for a digital data counterfeit detection.

Abstract: An EGR system comprises a vacuum-operated EGR valve and an auxiliary valve of a diaphragm type for assisting the operation of the EGR valve. A diagnostic control unit monitors an engine rotational fluctuation parameter such as a misfire parameter under the condition of EGR and judges that there is a possibility of abnormality in the auxiliary valve when the fluctuation parameter is greater than a first judgment value. In response to this judgment, the diagnostic control unit forcibly cuts off the EGR and calculates the fluctuation parameter under the condition of EGR cutoff. The diagnostic control unit concludes that the auxiliary valve is abnormal when the fluctuation parameter in the EGR cutoff state is smaller than or equal to a second judgment value which is smaller than the first judgment value.

Abstract: In a leak diagnostic system of an evaporative emission control system for an internal combustion system, which utilizes a change in internal pressure in a predetermined fluid-flow passage ranging from a fuel tank via a canister to a purge control valve, in addition to a relative-pressure sensor for sensing the internal pressure, an atmospheric-pressure sensor is provided for sensing atmospheric pressure. The leak diagnostic system includes a control module which samples the pressure in the predetermined fluid-flow passage as a first fluid-flow passage pressure at a first sampling time when a predetermined decompressing operation is completed, and samples the pressure in the predetermined fluid-flow passage as a second fluid-flow passage pressure at a second sampling time when a predetermined time interval has been elapsed from the first sampling time.

Abstract: An abnormality diagnosis apparatus of an engine cooling system includes a cooling water temperature sensor 14 for detecting a cooling liquid temperature. A control unit 12 calculates a rise value of the cooling liquid temperature in a measuring section, and judges a liquid temperature convergence time at which the rise value of the cooling liquid temperature in the measuring section becomes smaller than a predetermined value, and if the cooling liquid temperature, when the liquid temperature is converged, is lower than a criteria value, the apparatus diagnoses that an abnormality is generated in the cooling system.

Abstract: At the time of a stop of an engine, a diagnostic control unit shuts off a purge line with a purge control valve and an atmospheric port of a canister with a drain cut valve, and thereby holds an evaporative emission control circuit inclusive of a fuel tank and the canister in a state of a closed space during an off period of the engine. At the time of a next start of the engine, the diagnostic control unit measures a pressure in the closed circuit with a pressure sensor and checks a pressure decrease due to condensation of fuel vapors in the closed circuit to determine the existence or nonexistence of leakage.

Abstract: An evaporative emission control system is provided which includes a bypass valve, purge control valve and a vent control valve. To make a leak diagnosis, firstly the vent control valve is closed while the purge control valve is opened, whereby to negatively pressurize the inside of a fuel vapor conduit portion extending from the bypass valve to an intake pipe side. After the pressure in the fuel vapor conduit portion from the bypass valve to the intake pipe is reduced to a predetermined value, the purge control valve is closed. Then, the bypass valve is opened, and after lapse of a predetermined time from the opening of the bypass valve a variation of pressure in a conduit extending from the fuel tank to the purge control valve is asured. Based on the variation of pressure, a leak diagnosis is made.

Abstract: There is provided an apparatus for detecting a leak in an evaporative emission control system for an internal combustion engine including a fuel tank, a canister for collecting fuel vapors from the fuel tank, and a purge control valve disposed between the canister and the intake pipe for allowing flow of the fuel vapors from the canister to the intake pipe such that a fuel vapor flow passage is provided which extends from the fuel tank to the purge control valve by way of the canister.

Abstract: A diagnostic device and method for an exhaust gas recirculation system achieves a prompt diagnosis without reducing accuracy. The diagnosis of an exhaust gas recirculation system, which is carried out based on an EGR temperature and an operating signal for operating an EGR control valve, is prevented when the EGR temperature is greater than a predetermined temperature, except when a rising rate of the EGR temperature is greater than a predetermined value.

Abstract: In an internal combustion engine, first and second oxygen sensors are installed in an exhaust system at positions upstream and downstream of a three-way catalytic converter. An air-fuel ratio control device usually controls the air-fuel ratio of mixture fed to the engine in accordance with an output issued from the first oxygen sensor. The control device is capable of correcting, upon a given diagnosing mode thereof, the air-fuel ratio of mixture to a generally stoichiometric value in accordance with a rich/lean reverse of an output issued from the second oxygen sensor. A time lag detecting device detects the elapsed time from the time on which the output from the oxygen sensor carries out a rich/lean reverse to the time on which the output from the second oxygen sensor carries out a corresponding rich/lean reverse. A judging device judges a deterioration degree of the catalyst in accordance with the time lag.

Abstract: A diagnostic system makes a diagnosis on a variable valve timing control system mounted on an internal combustion engine by forcibly switching the valve timing control system from an operative state to an in operative state. The diagnostic system comprises sensors for detecting a variation of an operating state of an internal combustion engine, based on the forcible switching operation, and for detecting a throttle valve opening of the engine. The diagnostic system makes the diagnosis by comparing a variation of rate of flow of intake-air with a predetermined reference value to determine whether the valve timing control system operates normally or abnormally. The diagnostic system provides both a predetermined diagnostic preparatory period and a predetermined actual diagnostic period.

Abstract: A learning control system for controlling an air fuel ratio an engine employs a slowly updated second learning control variable in addition to a normally updated first learning control variable in order to utilize the learning function sufficiently even when a deviation of the air fuel ratio exceeds the learning range of the first variable. The control system according to an illustrated embodiment of the invention identifies a current engine operating area among a plurality of such areas, in accordance with a sensed engine operating condition, obtains a value of the first learning variable corresponding to the identified operating area, and a value of the second learning variable, determines a learning quantity which is a sum of the first and second learning variables by using the obtained values, and uses this learning quantity for determining a desired fuel supply quantity. The second learning variable is updated slowly whereas the first learning variable is updated in a sensitive and speedy manner.

Abstract: A leak diagnosis system is provided for diagnosing a leak condition of an evaporative emission control system for an internal combustion engine. The leak diagnosis system receives a signal indicative of a pressure in the evaporative emission system and obtains a converged limit negative pressure in the evaporative emission control system when the evaporative emission control system is communicated with the operating engine. The leak diagnosis system diagnoses a leak condition by comparing the converged limit negative pressure with a leak decision value.

Abstract: In a device for judging of misfire of an internal combustion engine from a variation of crankshaft rotational speed during combustion stroke of each cylinders, a measurement period for measurement of crankshaft rotational speed at a cylinder is set by counting a predetermined number of first signals indicative of a predetermined rotational angle of a crankshaft firstly on the basis of a second signal indicative of a reference position of a camshaft and secondly and onward on the basis of the first signals used for setting the previous measurement section.

Abstract: A leak diagnosis system which diagnoses a leak condition of an evaporative emission control system for an internal combustion engine. The leak diagnosis system detects a changing speed of a pressure in the evaporative emission control system for plural times during when the evaporative emission control system is put into a negative pressure condition by the negative pressure of the engine and is then closed by a purge-cut valve. The leak diagnosis system diagnoses a leak condition of the evaporative emission control system according to the detected plural pressure changing speeds while taking a fuel condition in the evaporative emission control system into consideration on the basis of the detected plural pressure changing speeds. Accordingly, the leak condition in the evaporative emission control system is accurately diagnosed without being effected by the fuel condition.