Nippondenso Co., Ltd.

Takashi Arimura

Toshimi Matsumura

Hisamitsu Yamazoe

Mitsunori Takao

Norio Omori

Masao Yonekawa

Hisashi Kadowaki

Hideya Fujisawa

Kiyotaka Nishiura

An apparatus capable of performing correct determination of a misfire limit without involving influence by differences between individual internal combustion engines, and thus capable of realizing highly precise lean control. During lean control, a mean deviation MD.sub..lambda.=1 of angular-velocity differences, which has been learned during the adoption of the stoichiometric air-fuel ratio (i.e., during .lambda.=1) in the relevant internal combustion engine, is subtracted from the current mean deviation MD.sub.L of angular-velocity differences occurring in the engine, so that the fuel injection amount is corrected in accordance with the resultant difference .DELTA.MD, which is attributable to an increase in the risk of misfire. Thus, the mean deviation component MD.sub..lambda.=1 which corresponds to the stoichiometric air-fuel ratio and which may differ between individual internal combustion engines, is eliminated, and only the component .DELTA.MD attributable to an increase in the risk of misfire is used to control the air-fuel ratio, thereby eliminating influence of differences between internal combustion engines to enable correct determination of a misfire limit.

Air fuel ratio control apparatus for internal combustion engine

A detector for detecting amount of suction air or rotating speed of an internal combustion engine supplies the detection signal to a control circuit, which supplies a drive signal to an air control valve mounted in a suction pipe of the internal combustion engine in accordance with the detection signal from the detector so that an idling rotating speed of the internal combustion engine is increased to a predetermined speed.

Internal combustion engine control apparatus

In an internal combustion engine, a basic fuel injection pulse width is calculated by parameters such as the engine speed and the intake-air quantity. The basic pulse width is compensated for by an integration compensation factor and a learning correction factor so as to obtain a desired air-fuel ratio. A predetermined number of integration compensation factors are sampled at every air-fuel ratio transition, and the mean value thereof is calculated. The learning compensation factor is corrected in accordance with the mean value of the predetermined number of integration compensation factors.

Method and apparatus for controlling the air-fuel ratio in an internal

The idle speed of an internal combustion engine is controlled in response to a variable ignition timing control signal from a microcomputer. The microcomputer derives this control signal as a function of the magnitude of engine speed variation which occurs during engine idle periods to cause the ignition timing to vary quickly in response to a transitory engine load variation. An auxiliary air delivery system may be advantageously incorporated in the idle speed control system to cooperate with the ignition timing control in response to the engine speed variation.

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Kariya, Japan

Takashi Arimura