Abstract: A rotation signal outputting device outputs a rotation signal at every predetermined rotational angle of an engine output shaft. An actual measurement value calculating device measures an amount of time spent by multiple engine cylinders in rotation between predetermined rotational angles during an expansion stroke, the measurements being made based on rotation signals output by the rotation signal outputting device. The actual measurement value calculating device also calculates an actual measurement value in response to the measured time interval. A first variation amount calculating device calculates a first difference between actual measurement values in two cylinders of the engine, and calculates a first variation amount in response to the calculated first different.

Abstract: A misfiring detecting device comprising a sensor for detecting the angular velocity of the crankshaft. The elapsed time required for the crankshaft to rotate by a certain crank angle is detected at the time of combustion at each cylinder. The difference .DELTA.T.sub.n (=T.sub.n -T.sub.n-2) of the elapsed time T between cylinders with explosion strokes one interval apart is found and it is judged that a misfire has occurred when the difference .DELTA.T.sub.n has exceeded a set value K.sub.1 and also the pattern of change of the elapsed time (.DELTA.TC) has become the pattern of change of the time of a misfire.

Abstract: A control system equipped with a misfire detection apparatus for an internal combustion engine comprising a first storage for storing a data train indicative of a record of a predetermined number of the operation states detected at a predetermined interval and a second storage for storing a reference data train indicative of a reference record of a predetermined number of reference operation states. The misfire detection apparatus further includes a comparison calculator for comparing each data constituting the data train stored in the first storage with each data constituting the reference data train stored in the second storage to obtain a comparison result between the entire data train and the entire reference data train. The comparison result supplied to a decision section to decide that the engine is in a predetermined state when the comparison result is out of a predetermined range.

Abstract: In a misfire detecting apparatus for a multicylinder internal combustion engine, a rotational signal outputting unit outputs a rotary signal at every predetermined rotary angle, and a tentative misfire decision unit tentatively decides, on the basis of the rotary signal, whether or not misfire has occurred in each cylinders of the engine. A tentative misfire number counting unit counts the number of tentative misfires decided for respective cylinders, and a counting result storage unit stores the counting results. After a given number of tentative misfire decisions have been made, it is decided that misfire has actually occurred, only if the counting result, for a part of the cylinders, among the counting results for respective cylinders stored in the counting result storage unit is larger than a predetermined number.

Abstract: A misfire detecting apparatus for an internal combustion engine which detects the occurrence of misfire in the engine on the basis of a rotation signal outputted in accordance with the rotation of the engine at every predetermined rotational angle a crank shaft of said engine. The apparatus successively calculates a time taken for revolution of the engine by a predetermined crank angle on the basis of the rotation signals outputted from the rotational angle sensor and then sets first and second decision values on the basis of the calculated times in connection with two cylinders of the engine which successively take explosion strokes. The second decision value is set at 360 degrees in the engine rotational angle previous to the setting of the first decision value. The apparatus detects the occurrence of misfire on the basis of the first and second decision values. This arrangement can accurately detect the occurrence of misfire irrespective of the difference in average speed between the respective cylinders.

Abstract: A control system equipped with a misfire detection apparatus for an internal combustion engine comprising a first storage for storing a data train indicative of a record of a predetermined number of the operation states detected at a predetermined interval and a second storage for storing a reference data train indicative of a reference record of a predetermined number of reference operation states. The misfire detection apparatus further includes a comparison calculator for comparing each data constituting the data train stored in the first storage with each data constituting the reference data train stored in the second storage to obtain a comparison result between the entire data train and the entire reference data train. The comparison result supplied to a decision section to decide that the engine is in a predetermined state when the comparison result is out of a predetermined range.

Abstract: A spark timing control apparatus controls the spark timing to retard or advance in accordance with the output signal from a knock sensor. An accelerating condition of the engine is determined depending on a particular knock occurence patterns including; whether the interval of knock occurences is larger or small, the total amount of retard angles is larger or small, or the frequency of knock occurences. When the accelerating condition is determined, the advancing rate of the spark timing is increased until a steady state of the engine operation is determined based on the output signal of the knock sensor.