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Method of adjusting a fuel composition estimate

  • US 8,903,626 B2
  • Filed: 06/24/2011
  • Issued: 12/02/2014
  • Est. Priority Date: 06/24/2011
  • Status: Expired due to Fees
First Claim
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1. A method of adjusting a fuel composition estimate for a vehicle, the method comprising:

  • sensing a refueling event;

    after sensing the refueling event, determining whether an air-fuel ratio sensor is operable to provide an updated estimate of fuel composition; and

    providing an updated fuel composition estimate if the air-fuel ratio sensor is not operable, including performing steps comprising;

    monitoring estimated engine torque to determine whether first variations in engine torque over a first period after the refueling event exceed a threshold; and

    modifying a previous first fuel composition estimate prior to the refueling event by a first pre-determined amount to determine a second estimate of fuel composition if the first variations in engine torque exceed the threshold after the refueling event and while the air-fuel ratio sensor is not operable for providing an updated fuel composition estimates;

    the method further comprising;

    modifying the second estimate of fuel composition by a second amount if, after performing the step of modifying the first estimate of fuel composition by the first pre-determined amount, second variations of engine torque again exceed the threshold; and

    wherein the step of modifying the second estimate of fuel composition by the second amount comprises;

    comparing the first variations in engine torque prior to a first correction with the second variations in engine torque occurring after determining the second estimate of fuel composition for the first correction; and

    modifying the second estimate of fuel composition by a second pre-determined amount that is substantially the same as the first pre-determined amount to obtain a third estimate of fuel composition if the first variations and the second variations are substantially the same.

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