Fuel vapor line diagnostics
First Claim
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1. A method, comprising:
- reverse rotating an engine unfueled in a direction opposite to a direction of engine rotation for vehicle propulsion and opening a purge valve to apply positive pressure, generated via the reverse rotating, from an intake manifold on a fuel vapor system; and
indicating disconnection of a connector coupled to a fuel vapor conduit of the fuel vapor system based on a pressure response following application of the positive pressure.
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Abstract
Methods and systems are provided for diagnosing fuel vapor leaks due to un-latching of quick connectors in interfaces of a fuel vapor system. In one example, a method may include using positive pressure generated in the intake manifold by reverse rotation of the engine unfueled, to detect un-latching of quick connectors in the fuel vapor system. After the positive pressure test, a negative pressure test is performed on the fuel vapor system to confirm any un-latching of quick connectors.
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Citations
19 Claims
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1. A method, comprising:
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reverse rotating an engine unfueled in a direction opposite to a direction of engine rotation for vehicle propulsion and opening a purge valve to apply positive pressure, generated via the reverse rotating, from an intake manifold on a fuel vapor system; and indicating disconnection of a connector coupled to a fuel vapor conduit of the fuel vapor system based on a pressure response following application of the positive pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for an engine, comprising:
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sequentially applying positive pressure from an engine and then vacuum from the engine on a fuel vapor system; monitoring a manifold pressure (MAP) response following each of the applying positive pressure and vacuum; and indicating un-latching of a connector coupled to a fuel vapor system conduit based on the MAP response, including indicating un-latching of the connector in response to a higher than threshold change in manifold pressure following each of the applying positive pressure and vacuum. - View Dependent Claims (13, 14, 15, 16)
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17. A hybrid vehicle system, comprising:
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vehicle wheels propelled via one or more of an engine and an electric motor; an engine intake manifold including an intake throttle; a pressure sensor coupled to the engine intake manifold for estimating a manifold pressure; a fuel vapor system including a fuel tank coupled to a canister, a fuel vapor conduit, and a quick-disconnect connector coupled to the fuel vapor conduit; a canister purge valve coupling the canister to the engine intake manifold; an isolation valve coupling the canister to the fuel tank; a port for receiving a diagnostic tool; and a controller with computer readable instructions stored on non-transitory memory for; in response to coupling of the diagnostic tool to the port, transitioning the engine to a service mode to initially apply positive pressure from the intake manifold on the fuel vapor system via reverse engine rotation and subsequently apply negative pressure from the intake manifold on the fuel vapor system via forward engine rotation; and setting a diagnostic code to indicate un-latching of the connector based on a higher than expected change in manifold pressure following each of the applying of the positive pressure and the negative pressure, the diagnostic code set until an operator input indicative of reconnecting of the connector is received. - View Dependent Claims (18, 19)
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Specification