Systems and methods for evaporative emissions testing
First Claim
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1. A method, comprising:
- following a vehicle-off event, waking an electronic controller to indicate an absence of a vapor leak in an evaporative emissions system responsive to vacuum in the evaporative emissions system attaining a vacuum threshold, the vacuum threshold determined at the vehicle-off event by the electronic controller and the vacuum threshold based on ambient conditions and fuel conditions, and sleeping the electronic controller after determining the vacuum threshold.
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Abstract
Methods and systems are provided for diagnosing degradation of an evaporative emissions system in a vehicle. One example method comprises following a vehicle-off event, waking an electronic controller to indicate an absence of a leak in the evaporative emissions system responsive to vacuum in the evaporative emissions system attaining a vacuum threshold, the vacuum threshold based on ambient conditions and fuel conditions at the vehicle-off event. The vacuum threshold may vary based on existing conditions and may enable a more reliable diagnosis of a status of the evaporative emissions system.
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Citations
19 Claims
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1. A method, comprising:
following a vehicle-off event, waking an electronic controller to indicate an absence of a vapor leak in an evaporative emissions system responsive to vacuum in the evaporative emissions system attaining a vacuum threshold, the vacuum threshold determined at the vehicle-off event by the electronic controller and the vacuum threshold based on ambient conditions and fuel conditions, and sleeping the electronic controller after determining the vacuum threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for a vehicle, comprising:
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a fuel system including a fuel tank; an evaporative emissions system coupled to the fuel system; a pressure sensor coupled to the evaporative emissions system and the fuel system, the pressure sensor measuring a pressure in the evaporative emissions system and fuel system; a powertrain control module comprising a wake input; and a comparator circuit coupled to the wake input, the powertrain control module configured with instructions stored in non-transitory memory that when executed cause the powertrain control module to; in response to a vehicle-off event, estimate a vacuum threshold based on each of ambient conditions and fuel conditions; sleep following estimating the vacuum threshold while maintaining the comparator circuit awake; and responsive to vacuum in the evaporative emissions system reaching the vacuum threshold, wake up and indicate a robust evaporative emissions system; and sleep following the indication. - View Dependent Claims (11, 12, 13, 14)
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15. A method, comprising:
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controlling fuel delivered to an engine by a controller; before turning off the controller after shutdown of the engine, estimating pressure an evaporative emissions system would achieve after the shutdown based on ambient conditions and fuel conditions; determining whether a vapor leak exists in the evaporative emissions system after the controller turnoff in response to a comparison of actual pressure of the evaporative emissions system to the estimated pressure; and outputting a result indicating an absence of the vapor leak in response to the actual pressure being equal to the estimated pressure. - View Dependent Claims (16, 17, 18)
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19. A method, comprising:
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following a vehicle-off event, waking an electronic controller to indicate an absence of a vapor leak in an evaporative emissions system responsive to vacuum in the evaporative emissions system attaining a vacuum threshold, the vacuum threshold determined at the vehicle-off event by the electronic controller and the vacuum threshold based on ambient conditions and fuel conditions; and enabling a sleep mode of the electronic controller after indicating the absence of the vapor leak.
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Specification