Abstract: An engine control unit of a control apparatus for an in-cylinder injection internal combustion engine sets a fuel injection timing for a compression-stroke injection mode in accordance with a fuel injection quantity, and corrects the fuel injection timing according to an engine cooling water temperature. When the cooling water temperature is lower than a temperature observed when a warm-up operation is completed, the fuel injection timing for the compression-stroke injection mode is corrected for advance or retard on the basis of the engine characteristic proper, and fuel is injected at an appropriate time such that the fuel evaporation rate and the fuel stratification degree which permit the stabilized combustion of the fuel injected into the combustion chamber are attained, whereby the fuel is evaporated satisfactorily. Thus, the occurrence of misfire and the emission of harmful gas components can be restrained effectively during the warm-up operation in the compression-stroke injection mode.

Abstract: A method and apparatus for detecting faults in a fuel evaporative emission control system, in which the fuel evaporative emission which is admitted from a fuel tank and adsorbed once by a canister is separated from the canister by purge air and sucked into a suction passage of an engine. The fault diagnostic apparatus fluid-tightly closes the fuel tank such that a vacuum is held in the fuel tank, and then detect the presence of a leak in a fuel evaporative emission flow path on the basis of a rate of increase of the pressure in the fuel tank. At the same time, the average value of the pressure in the fuel tank is calculated at regular intervals, and the calculated average value is compared with levels of the pressure in the tank detected within a predetermined period of time, so that the detection of the leak is interrupted depending upon the result of the comparison.

Abstract: This invention relates to a control system and method for an in-cylinder injection internal combustion engine, which perform control of the timing of fuel injection, the timing of ignition and an EGR rate to assure the stability of combustion in the engine and also its exhaust gas cleaning performance while promoting an improvement in gas mileage by performing injection in compression strokes.

Abstract: A detecting apparatus for a catalytic converter has a pair of O.sub.2 sensors, arranged individually on the up- and downstream sides of the converter, and an electronic control unit for discriminating reduction of the purifying capacity of a three-way catalyst in the converter. This unit discriminates the reduction of the purifying capacity in accordance with the comparison between a decision value and the ratio between the respective frequencies of outputs from the O.sub.2 sensors. In the case where the O.sub.2 sensor on the upstream side is subject to thermal degradation, its decision value is corrected, or the decision itself is interrupted.

Abstract: A fault diagnosis apparatus for detecting a fault in a fuel evaporative emission suppressing system, if it is concluded that an engine (1) is being operated in an operating state fulfilling fault diagnosis execution conditions, detects the current valve opening position of an idling speed control (ISC) valve (8) and then drives a purge control valve (46) to open the same. If a relatively high load is applied to the engine at this time, the threshold value determining the operating sensitivity of the ISC valve is so corrected as to be decreased. When a predetermined period of time has elapsed from the moment when the valve opening position of the ISC valve is detected, the valve opening position of the ISC valve is detected again. If the deviation between these valve opening positions is not larger than the threshold value, it is concluded that the purge air introduction by the drive of the purge control valve is not performed, that is, it is concluded that the valve is faulty.

Abstract: An air-fuel ratio of respective (individual) cylinders of an engine is changed individually from a stoichiometric air-fuel ratio to a lean air-fuel ratio with the change timing of each of respective cylinders deviated and the intake air flow into an engine 11 is changed gradually by opening an air bypass valve in parallel to the changing of the air-fuel ratio. Concurrent change of ignition timing is also disclosed.

Abstract: A fault diagnosis apparatus for detecting a fault in a fuel evaporative emission suppressing system comprises an electronic control unit. When fault diagnosis execution conditions are fulfilled, the electronic control unit stores an average of integral term values for air-fuel ratio feedback control, operating position of an idling speed control valve, and engine speed, and then actuates a purge control valve of the suppressing system so that the valve opens. In a predetermined time period after the actuation of the purge control valve, the integral term average and the like are stored again. If any changes of the integral term average and other values caused by the actuation of the purge control valve are detected, the suppressing system is concluded to be normal. If no changes are detected, on the other hand, the suppressing system is concluded to be faulty.

Abstract: An apparatus for determining a failure of an exhaust gas recirculation (EGR) apparatus includes an electronic control unit. When judging the fulfillment of the failure diagnosis executing condition, the electronic control unit stores the intake pressure detected by a pressure sensor, and then introduces part of the exhaust gas from an engine to an intake passage via an EGR passage to start the EGR for failure diagnosis. Thereafter, the intake pressure is detected again. If a significant change in intake pressure does not occur before and after the execution of the EGR for failure diagnosis, it is judged that the EGR apparatus is faulty.

Abstract: ECU includes a lean air/fuel ratio coefficient setting device, an accelerated stoichiometric-burn operation air/fuel ratio coefficient setting device, a meeting-of-lean-burn-operation-conditions determining device, a throttle position change detector, an acceleration criterion setting device, an end-of-acceleration determining device and an acceleration determining device. When a detected vehicle speed has been determined to be in a high-speed range faster than a threshold and an acceleration is determined to have ended, a relatively large value is set as an acceleration criterion only for a predetermined period. During a lean-burn operation, ECU compares output information from the throttle position change detector with the acceleration criterion set by the acceleration criterion setting device and if the output information is greater than the acceleration criterion, determines an accelerated operation and changes the mixing ratio of fuel to air to a stoichiometric ratio (or a rich ratio).

Abstract: An alr-fuel ratio controller for-an internal-combustion engine is provided with front and rear O.sub.2 sensors respectively installed in the exhaust system on the upstream and downstream sides of an exhaust gas purifier. The controller corrects the air-fuel ratio in accordance with the result of the comparison between a detected value of the front O.sub.2 sensor and a first reference value, to thereby control the alr-fuel ratio to a desired value, and also corrects a value of a parameter related preferably to at least one of a correction amount or a correcting timing for the air-fuel ratio correction, e.g., the first reference value, in accordance with the deviation between a detected value of the rear O.sub.2 sensor and a second reference value.

Abstract: An ignition timing control system for an internal combustion engine of the spark ignition type such as a gasoline engine. A throttle opening of the engine is sampled and a throttle opening variation is calculated. A real volumetric efficiency is calculated based on a real intake air amount and a real engine rotational speed by a real volumetric efficiency calculating device and the real volumetric efficiency is corrected based on the throttle opening variation by a volumetric efficiency correcting device to calculate an effective volumetric efficiency. An ignition timing is set in accordance with the effective volumetric efficiency and the engine rotational speed by an ignition timing setting device and an ignition timing controlling signal is developed based on the ignition timing set by the ignition timing setting device. An igniting device operates upon reception of the ignition timing controlling signal.

Abstract: Disclosed is a method for controlling the quantity of intake air supplied to an internal combustion engine, in which the position of a valve member of a flow control valve having a non-linear valve opening characteristic is converted into an intake air quantity or a virtual valve position proportional to the intake air quantity so as to linearize the non-linear valve opening characteristic of the flow control valve. Application of the method of the present invention to an idle speed control device in an engine equipped with an electronic controlled fuel injection system is advantageous in that the quantity of intake air supplied to the engine can be accurately controlled under various operating conditions of the engine, therely preventing rotation of the engine at an excessively high speed and stalling of the engine, improving the fuel consumption and reducing noise generated from the engine.