SYSTEM AND METHOD FOR PERFORMING EVAPORATIVE LEAK DIAGNOSTICS IN A VEHICLE
First Claim
1. A method for performing an evaporative leak diagnostic for a vehicle, 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.
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Accused Products
Abstract
A vehicle is provided with a fuel system, a controller, and a diagnostic module with an orifice, a pressure sensor, and a pump, the module connecting the fuel system to atmosphere. The controller measures a reference pressure across the orifice to provide a threshold, isolates the fuel system, and provides a code in response to comparing a series or measured pressures to the threshold. A method for performing an evaporative leak diagnostic is provided. A valve in a diagnostic module is commanded to a vent position. A pump is operated to measure a reference pressure across an orifice to provide a threshold. A valve is commanded to a test position. The pump is operated to place the fuel system in a low pressure state, and a series of pressures in the fuel system is measured. A diagnostic code is provided after comparing the series of pressures to the threshold.
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Citations
20 Claims
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1. A method for performing an evaporative leak diagnostic for a vehicle, 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A vehicle comprising:
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a fuel system; a diagnostic module having an orifice, a pressure sensor, and a pump, the module connecting the fuel system to atmosphere; a controller configured to;
(i) measure a reference pressure across the orifice to provide a threshold;
(ii) isolate the fuel system in a low pressure state;
(iii) measure a series of pressures in the system; and
(iv) provide a code in response to comparing the series to the threshold. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A vehicle comprising:
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a first prime mover; a fuel system having a fuel tank connected to a canister by an isolation valve, the canister connected to the first prime mover; a second prime mover; a diagnostic module having a changeover valve, an orifice, a pressure sensor, and a pump, the module connecting the fuel system to atmosphere; a controller configured to;
(i) measure a reference pressure across the orifice to provide a threshold with the changeover valve in a first position;
(ii) command the isolation valve to a closed position and command the changeover valve to a second position to isolate the fuel system;
(iii) command the pump to place the fuel system in a low pressure state;
(iv) measure a series of pressures in the fuel system;
(v) provide a diagnostic code when at least one of the series of pressure measurements crosses the threshold within a predetermined time; and
(vi) provide a diagnostic code when a slope of the series of pressure measurements after another predetermined time indicates a future pressure measurement crossing the threshold.
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Specification