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: An apparatus for detecting an abnormality of a fuel transpiration prevention system which includes a canister with an absorbing device and a control valve provided in a passage between a fuel tank and an intake pipe of an internal combustion engine so that a fuel gas generated within the fuel tank is absorbed by the absorbing device of the canister and introduced into the intake pipe by opening and closing the control valve in accordance with an operating state of said internal combustion engine. The apparatus includes a pressure detecting device for detecting a pressure within the fuel tank and a deviation calculating unit responsive to the output of the pressure detecting device for calculating a deviation between the pressure detected when the control valve opens the passage and the pressure detected when the control valve closes the passage. The apparatus decides an abnormality of the fuel gas supply system on the basis of the deviation calculated by the deviation calculating unit.

Abstract: Disclosed is an apparatus for detecting deterioration of a catalyst of an internal combustion engine having a plurality of cylinder banks in such a manner that the deterioration of the catalyst can be assuredly discriminated regardless of the presence of deviation of a control phase with respect to each cylinder bank. The influence of change of the air/fuel ratio can be eliminated considerably by reducing the air/fuel ratio correction coefficient for a right bank, or by also using the correction coefficient for the left bank as that for the right bank to cause the phases of them to be synchronized with each other, or by dither-controlling the right bank. Therefore, the change of the air/fuel ratio with respect to the left bank can be assuredly detected while necessitating one sub air/fuel ratio sensor.

Abstract: In a fuel amount control apparatus arranged to determine the amount of fuel to be fed to respective cylinders so that the scattering in torque generation throughout the cylinders is suppressed, the amount of correction which is either added to or subtracted from a basic fuel amount, is computed such that a sum total of fuel amount correction factors substantially equals zero. To this end the sum total of the correction factors is first computed and is then checked whether an absolute value of the sum total is greater than a predetermined value. When greater, a given amount is either added to or subtracted from correction factors respectively provided for respective cylinders.

Abstract: Fuel amount control apparatus arranged to determine the amount of fuel to be fed to respective cylinder so that the scattering in torque generation throughout the cylinders is suppressed. Correction amounts are first obtained during idling, and these correction amounts are then modified using at least one engine parameter so that they can be used not only in idle state but also other operating states. To this end, a correction factor is computed using engine speed or the like so as to modify the correction amounts thereby. As a result, a basic fuel amount is corrected by correction factors provided for respective cylinders where the correction factors are further modified to be suitable for any engine operating conditions, providing smooth rotation without uncomfortable vibrations.

Abstract: An apparatus for controlling an air-fuel ratio in internal combustion engines has an RPM sensor, a combustion composition sensor, an intake air sensor and so on. Detection signals from these sensors are fetched by a microprocessor. A RAM is arranged in the microprocessor and is continuously supplied with power. The RAM has a first memory area which is divided into a plurality of areas for storing correction data corresponding to operating states of the engine. All the correction data stored in the first memory area are added together and the sum is divided by a given constant so as to obtain an updated correction amount. This updated correction amount is stored in a second memory area. The updated correction amount in the second memory area reflects the correction data stored in the first memory area. Given correction data stored in the first memory area is read out corresponding to a given intake air flow, thereby enabling feedback control.

Abstract: In an air-fuel ratio control system for an internal combustion engine, the basic fuel injection amount computed from engine parameters such as engine speed and intake air flow is corrected by using map having air-fuel ratio compensation data stored battery back-up in accordance with the engine parameters. The compensation data is read out of the map in accordance with the parameters at the time of detection of the stable combustion state of the engine. When an output of an oxygen sensor is on lean side, a predetermined amount is added to the data thus read, while when the output of the oxygen sensor is on rich side, a predetermined amount is subtracted from the data thus read, thereby renewing the stored value.

Abstract: A method and an apparatus for controlling the air-fuel ratio in an internal combustion engine in which the calculation of the presumed amount of fuel attached to the wall of the intake port of the engine is effected for correcting the amount of the fuel supplied to the engine in order to compensate for the variation of the air-fuel ratio of the air-fuel mixture used in the combustion of the engine.