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Vapor purge system integrity diagnosis for a hybrid vehicle

  • US 8,336,526 B1
  • Filed: 01/24/2012
  • Issued: 12/25/2012
  • Est. Priority Date: 01/23/2012
  • Status: Active Grant
First Claim
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1. A method to test a vapor purge system (VPS) for an internal combustion engine in a hybrid vehicle, the method comprising:

  • measuring a pressure in the VPS;

    closing a first valve coupling a carbon canister of the VPS and atmosphere;

    decreasing pressure in the VPS if the pressure is greater than a threshold, the pressure decreased by;

    opening a second valve coupling the fuel tank and the engine while the engine is running; and

    closing the second valve when the pressure is below the threshold to provide a variable starting pressure in the VPS related to a manifold pressure for the engine; and

    monitoring pressure in the VPS for a predetermined time period to test for system integrity when the engine is at rest and the vehicle is operating.

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