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ABNORMALITY DIAGNOSIS APPARATUS FOR INTERNAL COMBUSTION ENGINE

  • US 20080110239A1
  • Filed: 10/30/2007
  • Published: 05/15/2008
  • Est. Priority Date: 11/10/2006
  • Status: Active Grant
First Claim
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1. An abnormality diagnosis apparatus for an internal combustion engine comprising:

  • an air-fuel ratio sensor provided in a confluent portion of exhaust gas discharged from each cylinder of the internal combustion engine, and detecting air-fuel ratio of the exhaust gas;

    an information detecting means for estimating an air-fuel ratio of each cylinder or a cylinder deviation of the air-fuel ratio based on an output of the air-fuel ratio sensor while an air-fuel-ratio dither control is performed for compulsorily varying the air-fuel ratio of each cylinder; and

    an abnormality determination means for determining that an abnormality occurs in a specified cylinder when a number of times in which the air-fuel ratio of the specified cylinder estimated by the information detecting means or a cylinder deviation of the air-fuel ratio exceeds a decision value is greater than a predetermined number.

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