EVAPORATIVE EMISSIONS SYSTEM AND METHOD FOR A STOP/START VEHICLE
First Claim
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1. A method, comprising:
- responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve;
indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow not decreasing while the canister purge valve is exposed to a threshold vacuum; and
adjusting an actuator in response to indicating the degradation.
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Abstract
Systems and methods for diagnosing individual components of an evaporative emissions system are presented. In one example, fuel vapor flow may be a basis for determining whether or not selected emission system components may be degraded. Further, fuel tank pressure may be another basis for determining component whether or not selected emissions system components may be degraded.
35 Citations
20 Claims
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1. A method, comprising:
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responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve; indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow not decreasing while the canister purge valve is exposed to a threshold vacuum; and adjusting an actuator in response to indicating the degradation. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method, comprising:
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responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve; indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow not decreasing while the canister purge valve is exposed to a threshold vacuum; otherwise, commanding close the canister vent valve, opening the canister vent valve, and opening the fuel vapor blocking valve; indicating a degradation of the fuel vapor blocking valve responsive to the fuel vapor flow not increasing while the canister purge valve is exposed to a threshold vacuum; and adjusting an actuator in response to degradation of the canister vent valve, the canister purge valve, or the fuel vapor blocking valve. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve; indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow estimate not decreasing while the canister vent valve is exposed to a threshold vacuum; otherwise, commanding open the fuel vapor blocking valve, opening the canister purge valve, and closing the canister vent valve; indicating excess flow in an evaporative emissions system responsive to the fuel vapor flow estimate increasing; and adjusting an actuator in response to degradation of the canister vent valve, the canister purge valve, or the indication of excess flow. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification