System and method for performing evaporative leak diagnostics in a vehicle
First Claim
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1. A method for performing an evaporative leak diagnostic for a vehicle, using a controller performing the steps, comprising:
- commanding a valve in a diagnostic module to a vent position, the valve connecting a fuel system to atmosphere;
operating a pump in the diagnostic module to measure a reference pressure across an orifice in the diagnostic module to provide a threshold;
commanding the valve to a test position;
operating the pump to place the fuel system in a low pressure state;
measuring a series of pressures in the fuel system; and
providing a diagnostic code after comparing the series of pressures to the threshold, wherein the diagnostic code is a fault code when at least one of the series of pressure measurements crosses the threshold within a predetermined time, wherein the threshold is a dynamically established threshold.
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Abstract
A method is provided for performing an evaporative leak diagnostic for a vehicle. A valve in a diagnostic module is commanded to a vent position. The valve connects a fuel system to atmosphere. A pump in the diagnostic module is operated to measure a reference pressure across an orifice in the diagnostic module to provide a threshold. The valve is commanded to a test position. The pump is operated to place the fuel system in a low pressure state. A series of pressures in the fuel system is measured. A diagnostic code is provided after comparing the series of pressures to the threshold.
66 Citations
13 Claims
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1. A method for performing an evaporative leak diagnostic for a vehicle, using a controller performing the steps, comprising:
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commanding a valve in a diagnostic module to a vent position, the valve connecting a fuel system to atmosphere; operating a pump in the diagnostic module to measure a reference pressure across an orifice in the diagnostic module to provide a threshold; commanding the valve to a test position; operating the pump to place the fuel system in a low pressure state; measuring a series of pressures in the fuel system; and providing a diagnostic code after comparing the series of pressures to the threshold, wherein the diagnostic code is a fault code when at least one of the series of pressure measurements crosses the threshold within a predetermined time, wherein the threshold is a dynamically established threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of performing an evaporative leak diagnostic for a vehicle comprising:
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providing a diagnostic module having an orifice, a pressure sensor, a changeover valve, a pump, and a controller, the valve and the orifice selectively providing a vapor flow path between a canister of a fuel system and atmosphere in response to a command from the controller; comparing, using a controller, a series of pressure measurements from the system in a low pressure state to a variable reference pressure measured across the orifice; and providing a code using the controller when at least one of the series of pressure measurements crosses a dynamically established threshold within a predetermined time.
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Specification