Abstract: A control system for an internal combustion engine with an automatic transmission having a torque converter, and a lock-up device. When gear shifting of the automatic transmission is carried out, the output torque of the engine is increased so as to reduce a shock caused by the gear shifting. The engaging force of the lock-up device is changed in response to the increase of the output torque.

Abstract: An automatic transmission of an automotive vehicle is set into a neutral position in response to a command instructing gear shifting of the automatic transmission when release of an accelerator pedal of the vehicle is detected. The automatic transmission has a plurality of speed clutches. The opening of a throttle valve arranged in an intake passage of an internal combustion engine installed on the vehicle is controlled such that the rotational speed of an input side of one of the speed clutches to be selected for the gear shifting and the rotational speed of the one of the speed clutches becomes substantially equal to each other when the automatic transmission is held in the neutral position. The one of the speed clutches is engaged upon detection that the rotational speed of the input side thereof and the rotational speed of the output side thereof becomes substantially equal to each other.

Abstract: A control system for an internal combustion engine for an automotive vehicle increases the output torque of the engine during an upshift of the automatic transmission so as to reduce a shock generated during the upshift. Time periods are measured over which respective speed clutches of the automatic transmission have been disengaged. The timing of increasing the output torque of the engine during the upshift of the automatic transmission is changed, based on one of the time periods measured over which one of the speed clutches of the automatic transmission to be selected for the upshift has been disengaged.

Abstract: A control system for an internal combustion engine for a vehicle has an automatic transmission. The control system is operable during gear shifting of the automatic transmission, for changing output torque of the engine to reduce a shock generated during the gear shifting. During gear shifting in which a change gear ratio of the automatic transmission is to be increased, upon stepping-on of the accelerator pedal of the vehicle, the output torque of the engine is increased by a first predetermined amount based on an operating condition of the vehicle when an increase occurs in the rotational speed of the engine due to the gear shifting. After the output torque of the engine is increased by the first predetermined amount, the output torque of the engine is decreased by a second predetermined amount based on the operating condition of the vehicle.

Abstract: An upshift of an automatic transmission of an automotive vehicle is carried out when a sudden decrease in a stepping-on amount of an accelerator pedal of the vehicle is detected. The opening of a throttle valve arranged in an intake passage of an internal combustion engine installed on the vehicle is closed when the stepping-on amount of the accelerator has increased during the upshift after the sudden decrease in the stepping-on amount. Engagement of one of speed clutches of the automatic transmission to be selected for the upshift is started upon the closing of the throttle valve. Control of the opening of the throttle valve in response to the stepping-on amount of the accelerator pedal is started after the rotational speed of the output side of the one of the speed clutches and the rotational speed of the input side of the same become substantially equal to each other through the engagement of the one of the speed clutches.

Abstract: A control system for an internal combustion engine for an automotive vehicle determines whether a catalytic converter arranged in the exhaust system of the engine is in a predetermined high temperature condition. When it is determined that the catalytic converter is in the predetermined high temperature condition, priority is given either to a decrease in the amount of intake air supplied to the engine or to an increase in the amount of fuel to be supplied to the engine, depending on operating conditions of the engine.

Abstract: A combustion state-determining system for an internal combustion engine has an ECU which determines a misfiring state of the engine, and calculates a misfiring rate of the engine, based on the result of the determination of the misfiring state. A catalyst temperature sensor detects the temperature of a catalytic converter as the exhaust system temperature, and the ECU determines the combustion state of the engine, based on the detected exhaust system temperature and the calculated misfiring rate. A combustion state control system restrains the output from the engine, based on the determination result of the combustion state-determining system.

Abstract: An evaporative fuel-processing system for an internal combustion engine includes an evaporative emission control system comprising charging passage extending between the canister and a fuel tank, a purging passage extending between the canister and an engine intake system, an open-to-atmosphere passage communicating the interior of the canister to the atmosphere, a purge control valve for opening and closing the purging passage, and an open-to-atmosphere valve for selectively opening and closing the open-to-atmosphere passage. A tank internal pressure sensor detects pressure within the evaporative emission control system. An ECU introduces negative pressure from the engine intake system into the evaporative emission control system and the fuel tank by opening the purge control valve and closing the open-to-atmosphere valve.

Abstract: A combustion state-detecting system for internal combustion engines has a crank angle sensor which generates a crank angle signal with a predetermined period shorter than a firing period of the engine whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A first average value of the detected engine rotational speed is calculated over every period of one rotation of the crankshaft, followed by calculating a second average value of the first average value over every firing period, to thereby calculate a rate of variation in the second average value over every firing period. Values of the rate of variation are averaged over a predetermined number of ignition cycles of the engine, to obtain a third average value. A cumulative value of the absolute value of a difference between the third average value and the rate of variation is calculated over the above predetermined number of ignition cycles.

Abstract: An evaporative fuel-processing system for an internal combustion engine includes a charging passage extending between the canister and the fuel tank of the engine, a purging passage extending between the canister and the intake system of the engine, an open-to-atmosphere passage for communicating the interior of the canister to the atmosphere, a first control valve for selectively opening and closing the purging passage, and a second control valve for selectively opening and closing the open-to-atmosphere passage. A tank internal pressure sensor detects pressure within the evaporative fuel-processing system, and an ECU determines abnormality of the evaporative fuel-processing system, based on a variation in the detected pressure after the interior of the evaporative fuel-processing system is negatively pressurized into a predetermined negative pressure state.

Abstract: An evaporative fuel-processing system for an internal combustion engine includes an evaporative emission control system having a fuel tank, a canister, a passage extending from the canister to an intake passage of the engine, and a purge control valve arranged across the passage, and a pressurization device for pressurizing the interior of the evaporative emission control system. An ECU actuates the pressurization device to bring the evaporative emission control system into a positively pressurized state, after the purge control valve and an open-to-atmosphere control valve arranged across a passage connected to the canister are closed, and detects an amount of evaporative fuel generated in the fuel tank. The ECU determines whether or not a leakage occurs from the evaporative emission control system, based on a rate of variation in pressure within the evaporative emission control system, and a reference value which is determined based on the amount of evaporative fuel detected.

Abstract: An evaporative emission control system includes a valve arranged in a passage communicating between a fuel tank and a canister. The valve opens the passage when pressure within part of the evaporative emission control system upstream of the valve exceeds a predetermined value and, closes the passage when the pressure is below the predetermined value. It is determined that the evaporative emission control system is normal when a value of the pressure with the part of the system detected by a pressure sensor is lower than a predetermined reference value below atmospheric pressure.

Abstract: A device according to an aspect of the invention detects abnormality of spark plugs of an internal combustion engine. A value related to electric resistance across a gap between electrodes of each spark plug is measured. Next, it is determined whether or not the measured value, related to the electric resistance, assumes a value indicating that the electric resistance is below a predetermined value, when the engine is determined to be in a non-combustive state. The spark plug is determined to be abnormal when it is determined that the measured value, related to the electric resistance, assumes the value indicating that the electric resistance is below the predetermined value. A misfire-detecting system according to another aspect of the invention incorporates the above device.

Abstract: A combustion state-detecting system, for internal combustion engines, has a crank angle sensor. The crank angle sensor generates a crank angle signal with a predetermined period shorter than a firing period of the engine whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A first average value of the detected engine rotational speed is calculated over a period of one rotation of the crankshaft, followed by calculating a second average value of the first average value over every firing period, to thereby calculate a rate of variation in the second average value over every firing period. The rate of variation is compared with a predetermined value, to determine whether or not the engine is in a degraded state of combustion.

Abstract: An evaporative fuel-processing system includes a first control valve arranged in a charging passage connecting between a fuel tank and a canister for adsorbing evaporative fuel generated from the fuel tank, a second control valve arranged in a purging passage connecting between the canister and an intake passage of the engine, a third control valve arranged in an air inlet port of the canister, and a system internal pressure sensor for detecting pressure within the system. The system is checked for a leak by monitoring a value of the pressure detected by the sensor after the system is negatively pressurized by closing the third control valve and opening the second control valve. The sensor is provided at a location upstream of the first control valve, and the first control valve is closed to detect a value of the pressure or a change thereof. Abnormality determination is carried out based on the detected value of the pressure.

Abstract: A combustion state-detecting system for internal combustion engines has a crank angle sensor which generates a crank angle signal with a predetermined period shorter than a firing period of the spark plug whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A rate of variation in the detected value of the rotational speed of the engine is calculated over the firing period of the spark plug, and an average value thereof is then calculated. The calculated average value of the variation rate is compared with the calculated variation rate, and a cumulative value of a difference between the calculated variation rate average value and the calculated variation rate is calculated when the calculated variation rate is on the larger deceleration side of the engine rotational speed with respect to the calculated variation rate average value.

Abstract: A misfire-detecting system for an internal combustion engine having a plurality of cylinders. A rotational speed of the engine is detected and a rotational speed signal indicative of the detected rotational speed of the engine is output. The rotational speed signal is filtered. Occurrence of a misfire in the engine is determined based on the filtered rotational speed signal.

Abstract: A misfire detecting system for an internal combustion engine, including an intake pipe internal pressure detecting device for detecting an internal pressure of an intake pipe of the internal combustion engine, and a misfire detection inhibiting device for inhibiting the detection of misfire when the internal pressure of the intake pipe detected by the intake pipe internal pressure detecting device is lower than an intake pipe internal pressure in a no-load condition.

Abstract: A combustion state-detecting system for an internal combustion engine calculates a first average speed by averaging the rotational speed of the engine over a time period corresponding to duration of one stroke of a cylinder, and a second average speed by averaging the rotational speed of the engine over a time period corresponding to duration of one cycle of all strokes of the cylinder. The system calculates a difference between the first average speed and the second average speed, and determines based on the difference whether or not the combustion state of the engine is abnormal.

Abstract: A tank internal pressure-detecting device for an internal combustion engine having an evaporative emission control system for controlling purging of evaporative fuel generated in a fuel tank thereof into an intake system thereof. An ECU interrupts purging of evaporative fuel by the evaporative emission control system for a predetermined period of time after the engine is started. The ECU causes control valves of the evaporative emission control system to open the interior of the fuel tank to the atmosphere, and stores a value of pressure within the fuel tank detected by a tank internal pressure sensor as a reference value while the purging is being interrupted and at the same time the interior of the fuel tank is opened to the atmosphere. The ECU corrects an output value of the tank internal pressure sensor, based upon the reference value stored.