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AssigneeDelphi Technologies, Inc.
InventorsStephen F. Majkowski, Michael J. Steckler, Kenneth M. Simpson, Malcolm James Grieve
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An improved method of diagnosing evaporative emission system leaks at engine idle, wherein the system is closed and drawn down to a sub-atmospheric pressure early in a driving cycle prior to the achievement of an idle condition appropriate for leak testing. When the test enabling conditions other than engine idle are met, the system vent is closed, and the purge valve is modulated to regulate the fuel tank pressure at a sub-atmospheric value substantially equivalent to the leak test pressure to be used at engine idle. When engine idle is achieved, the purge valve is closed, and the leak test is conducted with little or no delay. The time required to conduct the leak test is improved because the system pressure is at or near the test pressure when the engine idle condition is achieved, and at the same time, the reliability of the leak test data is improved because vapor generation equilibrium in the fuel tank is more nearly achieved when the leak test is initiated.
A method of diagnosing a leak in an automotive evaporative emission system during an engine idle condition of a driving cycle by measuring a system pressure, bringing the measured pressure to a reference value below atmospheric pressure, determining a rate of change of the measured pressure, and comparing the determined rate of change to a reference rate, the improvement wherein:
A method of diagnosing a leak in an automotive evaporative emission system during an engine idle condition of a driving cycle, including the steps of:
Dependencies are inferred from the claim text.