Abstract: A control system for an internal combustion engine having a plurality of cylinders and a switching mechanism for switching between an all-cylinder operation in which all of the plurality of cylinders are operated and a partial-cylinder operation in which at least one of the plurality of cylinders is halted. A condition for performing the partial-cylinder operation is determined, based on the detected operating parameters of the vehicle driven by the engine. A result of the determination is modified so that the partial-cylinder operation may be continued, when the detected operating parameters satisfy a predetermined continuation condition within a predetermined time period from the time a vehicle operating state where the condition for performing the partial-cylinder operation is satisfied, has changed to another vehicle operating state where the condition for performing the partial-cylinder operation is not satisfied.

Abstract: A knock control system for an internal combustion engine having a plurality of cylinders. Operation of the engine is switchable between a partial-cylinder operation for operating some of the cylinders and an all-cylinder operation for operating all of the cylinders. A determination threshold for determining knocking is set according to an output signal from the knock sensor. A level of the output signal from the knock sensor is compared with the determination threshold, and occurrence of knocking is determined according to a result of the comparison. The determination threshold used during the partial-cylinder operation is set to a value less than a value of the determination threshold used during the all-cylinder operation.

Abstract: A control apparatus for an internal combustion engine having a plurality of cylinders and a cylinder halting mechanism. The cylinder halting mechanism switches between an all-cylinder operation in which all of the plurality of cylinders are operated and a partial-cylinder operation in which at least one of the plurality of cylinders is halted. Operating parameters of the engine and the atmospheric pressure are detected. The cylinder halting mechanism is controlled to perform the all-cylinder operation or the partial-cylinder operation according to the operating parameters of the engine and the detected atmospheric pressure.

Abstract: An ignition timing control apparatus for an internal combustion engine having a plurality of cylinders, wherein operation of the engine is switchable between a partial-cylinder operation, which operates some of the cylinders, and an all-cylinder operation, which operates all of the cylinders. Basic ignition timing is calculated according to an operating condition of the engine. Knocking is determined based on an output of the knock sensor. A correction amount of the ignition timing is calculated according to a result of the knocking determination to suppress knocking, and the basic ignition timing is corrected with the calculated correction amount. Learning values of the correction amount are calculated corresponding, respectively, to partial-cylinder operation and all-cylinder operation, and one of the calculated learning values is used according to the operating condition of the engine.

Abstract: A control apparatus for an internal combustion engine having a plurality of cylinders and a cylinder halting mechanism. The cylinder halting mechanism switches between an all-cylinder operation in which all of the plurality of cylinders are operated and a partial-cylinder operation in which at least one of the plurality of cylinders is halted. Operating parameters of the engine and the atmospheric pressure are detected. The cylinder halting mechanism is controlled to perform the all-cylinder operation or the partial-cylinder operation according to the operating parameters of the engine and the detected atmospheric pressure.

Abstract: A control system for an internal combustion engine having a plurality of cylinders and a switching mechanism for switching between an all-cylinder operation in which all of the plurality of cylinders are operated and a partial-cylinder operation in which at least one of the plurality of cylinders is halted. A condition for performing the partial-cylinder operation is determined, based on the detected operating parameters of the vehicle driven by the engine. A result of the determination is modified so that the partial-cylinder operation may be continued, when the detected operating parameters satisfy a predetermined continuation condition within a predetermined time period from the time a vehicle operating state where the condition for performing the partial-cylinder operation is satisfied, has changed to another vehicle operating state where the condition for performing the partial-cylinder operation is not satisfied.

Abstract: An ignition timing control apparatus for an internal combustion engine having a plurality of cylinders, wherein operation of the engine is switchable between a partial-cylinder operation, which operates some of the cylinders, and an all-cylinder operation, which operates all of the cylinders. Basic ignition timing is calculated according to an operating condition of the engine. Knocking is determined based on an output of the knock sensor. A correction amount of the ignition timing is calculated according to a result of the knocking determination to suppress knocking, and the basic ignition timing is corrected with the calculated correction amount. Learning values of the correction amount are calculated corresponding, respectively, to partial-cylinder operation and all-cylinder operation, and one of the calculated learning values is used according to the operating condition of the engine.

Abstract: A knock control system for an internal combustion engine having a plurality of cylinders. Operation of the engine is switchable between a partial-cylinder operation for operating some of the cylinders and an all-cylinder operation for operating all of the cylinders. A determination threshold for determining knocking is set according to an output signal from the knock sensor. A level of the output signal from the knock sensor is compared with the determination threshold, and occurrence of knocking is determined according to a result of the comparison. The determination threshold used during the partial-cylinder operation is set to a value less than a value of the determination threshold used during the all-cylinder operation.

Abstract: There is provided a failure determination system for a variable-cylinder internal combustion engine which is capable of promptly and accurately carrying out failure determination of the valve-actuating system for cylinders for being made idle during a partial-cylinder operation mode. The failure determination system is capable of switching a cylinder operation mode between an all-cylinder operation mode in which all the cylinders are operated, and a partial-cylinder operation mode in which part of the cylinders are made idle. The failure determination system includes an ECU which executes a failure-determining operation mode for causing a valve-actuating mechanism to resume actuation of intake valves and exhaust valves of the part of the cylinders in a state in which fuel supply to the part of the cylinders is stopped, when the cylinder operation mode is shifted from the partial-cylinder operation mode to the all-cylinder operation mode.

Abstract: A control system for an internal combustion engine having a plurality of cylinders and a cylinder halting mechanism for halting operation of at least one of the plurality of cylinders. The cylinder halting mechanism is controlled to operate all of the plurality of cylinders or to halt the operation of the at least one of the plurality of cylinders. The operating state of the cylinder halting mechanism is detected based on the amount of change in the detected intake pressure of the engine.

Abstract: There is provided a failure determination system for a variable-cylinder internal combustion engine which is capable of promptly and accurately carrying out failure determination of the valve-actuating system for cylinders for being made idle during a partial-cylinder operation mode. The failure determination system is capable of switching a cylinder operation mode between an all-cylinder operation mode in which all the cylinders are operated, and a partial-cylinder operation mode in which part of the cylinders are made idle. The failure determination system includes an ECU which executes a failure-determining operation mode for causing a valve-actuating mechanism to resume actuation of intake valves and exhaust valves of the part of the cylinders in a state in which fuel supply to the part of the cylinders is stopped, when the cylinder operation mode is shifted from the partial-cylinder operation mode to the all-cylinder operation mode.

Abstract: A control system for an internal combustion engine having a plurality of cylinders and a cylinder halting mechanism for halting operation of at least one of the plurality of cylinders. The cylinder halting mechanism is controlled to operate all of the plurality of cylinders or to halt the operation of the at least one of the plurality of cylinders. The operating state of the cylinder halting mechanism is detected based on the amount of change in the detected intake pressure of the engine.

Abstract: In an engine including a variable timing/lift mechanism for an intake valve, journal portions of a valve-operating cam shaft are supported on cam bearing portions integrally provided in a cylinder head, and an intake rocker shaft is fixed by bolts to rocker shaft fixing portions provided on an upper surface of the cam bearing portions. By bringing opposite sides of intake rocker arms swingably supported on the intake rocker shaft into slidable abutment against positioning faces integrally formed on opposite sides of the cam bearing portions, the intake rocker arms are positioned in a thrust direction. Thus, it is possible to accurately and easily position the intake rocker arms in the thrust direction without the need for a special member.

Abstract: A high probability of detecting an erroneous misfire occurs when combustion becomes unstable during jolt control. Therefore, during jolt control the reliability of the misfire detection system is degraded. As a result, the misfire detection system is inactivated during jolt control by discontinuing the misfire detection, or by deliberately deeming no misfire has occurred if jolt control has occurred. Alternatively, the misfire detection sensitivity is masked during jolt control.

Abstract: A misfire-detecting system for an internal combustion engine detects occurrence of a misfire in the engine, based on voltage between both ends of a spark plug assumed when sparking discharge takes place at the spark plug. A diode is arranged in an ignition secondary circuit of the engine, for checking reverse current flowing in the circuit in a direction reverse to the direction of flow of current occurring when spark ignition takes place at the spark plug. An ECU detects reverse current flowing in the ignition secondary circuit, and detects an abnormality of the diode, based on the detected reverse current.

Abstract: A spark plug cap covering the terminal of a spark plug for an internal combustion engine, made up of an insulative cap body, an ignition coil unit case housing the coil and having a terminal for the ignition coil, a first conductive shaft housed in the insulative cap body for carrying an ignition voltage produced by the ignition coil to the spark plug terminal, and a second conductor located around the first conductor keeping a predetermined distance therefrom separated by the insulative material of the cap body such that a capacitor is formed between the first and second conductors for detecting the ignition voltage.

Abstract: An ignition coil unit for an internal combustion engine for containing an ignition voltage detective capacitor for misfire discrimination, including a core, a primary and a secondary coil wound around the core, and a case housing the core and the primary and secondary coils which is filled with an insulative material. In this unit, a first conductive electrode plate is placed in the case and electrically connected with the output of the secondary coil, and a second conductive electrode plate is also placed in the case in parallel with the first conductive electrode plate while maintaining a predetermined distance therefrom. An insulator is interposed between the first and second conductive electrode plates forming a capacitor that uses the insulator as the dielectric.

Abstract: A misfire-determining system for an internal combustion engine detects sparking voltage generated when ignition is sequentially performed for each of cylinders. Adjacent durations of sparking voltage detected for respective cylinders are separately compared with a predetermined reference value by respective different misfire-determining circuits to determine whether or not a misfire has occurred.

Abstract: A method of manufacturing a spark plug cap covering a spark plug for an internal combustion engine, equipped with an ignition voltage detective capacitor having a first conductor housed in a cap body for carrying an ignition voltage produced by an ignition coil to the spark plug and a second conductor located keeping a predetermined distance from the first conductor while sandwiching an insulative material such that the capacitor is formed between the first and second conductors for detecting the ignition voltage. The method comprises separately fabricating said insulative body and a member from the insulative material embedding said second conductor therein and fixing the member at said insulative body such that said detective capacitor is formed. The second conductor may be formed in the shape of a plate to be wound around the cap body.

Abstract: A misfire-detecting system for an internal combustion engine in which a value of sparking voltage is detected, which is generated across a spare plug when high voltage is generated by an ignition device in response to generation of an ignition command signal. When a time period over which the detected value of sparking voltage exceeds a predetermined reference voltage value exceeds a predetermined time period value, the system determines that a misfire has occurred in the engine. A recharging command signal is generated for applying high voltage to the spark plug, after generation of the ignition command signal. As a result, a misfire can be accurately detected.