Fuel vapor purging diagnostics
First Claim
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1. A method for a vehicle fuel vapor system coupled to an engine intake, comprising:
- during boosted conditions, intermittently adjusting a canister vent valve of a canister, a check valve positioned between the engine intake and the canister; and
indicating degradation, including reverse flow of gases from the engine intake to the fuel vapor system, based on a change in a pressure value in the fuel vapor system that correlates to the intermittent adjusting.
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Abstract
Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, the fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, intermittently adjusting a restriction in the fuel vapor recovery system during boosted conditions, and indicating degradation based on one or more of a change in a pressure value, or based on a change in flow in the fuel vapor recovery system.
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Citations
20 Claims
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1. A method for a vehicle fuel vapor system coupled to an engine intake, comprising:
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during boosted conditions, intermittently adjusting a canister vent valve of a canister, a check valve positioned between the engine intake and the canister; and indicating degradation, including reverse flow of gases from the engine intake to the fuel vapor system, based on a change in a pressure value in the fuel vapor system that correlates to the intermittent adjusting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system, comprising:
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an engine comprising an intake; an exhaust emission control device coupled to the engine; a boosting device with a compressor configured to provide a boost to the engine intake; a fuel vapor system coupled to the engine intake, said fuel vapor system including a fuel tank pressure transducer, a fuel vapor canister, a canister purge valve, a check valve and a canister vent valve; and a control system configured to, intermittently adjust a restriction in the fuel vapor system during a boosted condition; and indicate degradation, including reverse flow of gases from the engine intake to the fuel vapor system, based on a change in pressure value in the fuel vapor system that correlates to the intermittent adjusting. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification