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Misfire discriminating method and apparatus for an engine

  • US 5,862,505 A
  • Filed: 07/07/1993
  • Issued: 01/19/1999
  • Est. Priority Date: 07/21/1992
  • Status: Expired due to Fees
First Claim
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1. Misfire discriminating method for an engine, comprising:

  • detecting a first engine speed during a combustion stroke of a first cylinder;

    detecting a second engine speed during a combustion stroke of a second cylinder previous to the combustion stroke of the first cylinder;

    calculating a rotational difference corresponding to the first cylinder by subtracting the second engine speed from the first engine speed;

    computing a corrected rotational difference corresponding to the first cylinder by subtracting a present rotational difference correction value corresponding to the first cylinder from the rotational difference corresponding to the first cylinder;

    determining a rotational difference change corresponding to the first cylinder by subtracting a corrected rotational difference corresponding to the second cylinder from the corrected rotational difference corresponding to the first cylinder; and

    judging a misfire condition for the combustion stroke of the second cylinder whenthe rotational difference change corresponding to the first cylinder is equal to or larger than a first predetermined misfire level anda rotational difference change corresponding to the second cylinder is equal to or smaller than a second predetermined misfire level.

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