Abstract: A fuel control device for cylinder injection type internal combustion engines which is capable of cutting off fuel supplying to a combustion chamber depending upon an operating state of the engine and suitable for use in cylinder injection type engines, in which a compression stroke mode can be selected for the purpose of enabling shifting to fuel cutoff and shifting to fuel injection from cutoff without incurring shock of switching in the engine.

Abstract: In an intra-cylinder injection type engine, a first fuel cut-off starting rotational speed, a first return rotational speed and a first target idling speed in a compression stroke injection mode, which is superior in both combustion and responsivity, are set at lower speeds than a second fuel cut-off starting rotational speed, a second return rotational speed, and a second target idling speed in a suction stroke injection mode. During an operation in the compression stroke injection mode, a fuel cut-off mode and an idle running of the engine are practiced at a low engine speed, to improve the fuel economy without causing deterioration of combustion.

Abstract: When starting of an in-cylinder injection engine 1 is detected, a cylinder discrimination, which discriminates each cylinder, is effected. After each cylinder is discriminated, it is determined whether or not a water temperature detected by a water temperature sensor 16 exceeds a predetermined value. When the water temperature is below the predetermined value, fuel injection is started from the fuel injection valve 4 of a cylinder subjected to at least one compression stroke. Thereby, the cylinder discrimination is effected quickly, and it is made possible to raise the temperature within the combustion chamber 5, by means lapse of at least one compression stroke, at low water temperatures at which the starting ability tends to be deteriorated, and the starting ability of the in-cylinder injection engine 1 at low water temperatures is improved while shortening the starting time.

Abstract: A fault diagnosis apparatus for a fuel evaporative emission suppressing system has an electronic control unit which inputs an average value of integral terms for air-fuel ratio feedback control, engine speed, etc. when diagnosis executing conditions are satisfied, and then starts opening operation of a purge control valve. Subsequently, the average value of integral terms, engine speed, etc. are input again. If no substantial change occurs in the average value, etc. with driving of the purge control valve, it is concluded that purge air for fault diagnosis has not been introduced, and that the suppressing system is faulty. In driving the purge control valve, its driving duty ratio is increased by a relatively small increment till the driving duty ratio reaches a predetermined duty ratio.

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: A deterioration diagnostic apparatus for a three-way catalyst includes an electronic control unit, which obtains a frequency of reversals of the changing direction in which the output of an upstream-side O.sub.2 sensor changes, based on the number of times the output voltage of the O.sub.2 sensor crosses a threshold. Also, the control unit obtains a frequency of reversals of the changing direction in which the output of a downstream-side O.sub.2 sensor changes, based on the number of times the output voltage of the downstream-side O.sub.2 sensor crosses upper and lower reversal reference values which are obtained by adding and subtracting a hysteresis constant to and from an average value of input values of the downstream-side O.sub.2 sensor output voltage.

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: On an outer peripheral portion of a rotor (1), three protrusions are provided per each cylinder. A pickup coil 2 is disposed facing to the outer peripheral portion with a predetermined distance. A rotation signal (S.sub.0) is converted to a rotation signal pulse (S.sub.1) having three pulses (A, B and C) per each cylinder corresponding to the three protrusions. According to the first signal (A) of the rotation signal pulse (S.sub.1) the cranking ignition period (A.sub.1) is determined. According to the second signal (B) of the rotation signal pulse (S.sub.1), the starting timing for flowing current to the ignition coil (8) is decided. According to the third signal (C) of the rotation signal pulse (S.sub.1), the ignition timing at cranking operation is defined by detecting time intervals (3t, t, 2t) between the three signals (A, B, C).