SYSTEMS AND METHODS FOR DETERMINING CANISTER PURGE VALVE DEGRADATION
First Claim
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1. A method, comprising:
- during a first condition, opening a fuel tank isolation valve while maintaining a canister purge valve closed; and
indicating degradation of the canister purge valve based on an output of a universal exhaust gas oxygen (UEGO) sensor.
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Abstract
A method is provided, comprising: during a first condition, opening a fuel tank isolation valve while maintaining a canister purge valve closed; and indicating degradation of the canister purge valve based on an output of a universal exhaust gas oxygen (UEGO) sensor. The UEGO sensor output will indicate whether any fuel vapor vented from the fuel tank reaches intake through the commanded closed canister purge valve. In this way, canister purge valve degradation may be diagnosed in vehicles that do not include a functional fuel tank pressure sensor or canister vent valve.
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Citations
20 Claims
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1. A method, comprising:
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during a first condition, opening a fuel tank isolation valve while maintaining a canister purge valve closed; and indicating degradation of the canister purge valve based on an output of a universal exhaust gas oxygen (UEGO) sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A fuel system for a vehicle, comprising:
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a fuel tank coupled to a fuel vapor canister via a fuel tank isolation valve; an engine intake coupled to the fuel vapor canister via a canister purge valve; an universal exhaust gas oxygen (UEGO) sensor coupled to an engine exhaust; and a controller configured with instructions stored in non-transitory memory, that when executed, cause the controller to; responsive to an engine lean code, open the fuel tank isolation valve while maintaining the canister purge valve closed; and indicate degradation of the canister purge valve based on an output of the UEGO sensor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for a fuel system, comprising:
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responsive to a lean engine diagnostic code, maintaining a fuel tank isolation valve closed for a threshold duration; opening the fuel tank isolation valve while maintaining a canister purge valve closed; establishing a threshold output of an universal exhaust gas oxygen (UEGO) sensor based on one or more operating conditions; indicating degradation of the canister purge valve responsive to the output of the UEGO sensor decreasing below the threshold; and closing the fuel tank isolation valve.
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Specification