Unisia Jecs Corporation

Katsuyoshi Shiobara

Masanobu Ohsaki

Seiichi Ohtani

Michiyuki Fujimoto

A diagnosis system for a wide-range A/F sensor receives an air-fuel ratio (A/F) of air-fuel mixture supplied to an engine for the A/F sensor. An control unit of the diagnosis system corrects an A/F controlled object of a feedback control on the basis of a detection result of the A/F sensor to adjust the A/F at a target A/F. The control unit diagnoses an abnormality of the A/F sensor from variation of the detection value of the A/F sensor during a time period from the start of the switching of the target A/F. The control unit sets a control gain of an A/F feedback control at a value greater than a normal control gain during the diagnosis.

Diagnosis system for wide-range air-fuel ratio sensor

A diagnostic apparatus for supplying an assist air in an internal combustion engine includes: an assist air passage for guiding intake air from upstream of a throttle valve to a fuel injector installed downstream of said throttle valve; an assist air control valve installed in said assist air passage; a sensor for detecting an engine operating parameter; and a control unit. The control unit includes a data storage portion and a data processing portion. The control unit selectively forces the assist air control valve open and closed upon detection of at least one predetermined diagnosis condition. The control unit then calculates and stores a plurality of values corresponding to changes in the engine operating parameter based on signals received from the sensor, and determines an occurrence of an error with assist air supply based on comparisons of said values with a predetermined value.

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Gunma, Japan

Katsuyoshi Shiobara