Systems and methods for engine-off natural vacuum leak testing with fuel enablement compensation
First Claim
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1. A method for an evaporative emissions system, comprising:
- adjusting a threshold for an evaporative emissions leak test entry condition that comprises an engine heat rejection inference for an engine run time duration, based on at least a fuel level;
responsive to the engine heat rejection inference being greater than the adjusted threshold, adjusting one or more pressure thresholds for an evaporative emissions leak test based on the engine heat rejection inference; and
indicating degradation of the evaporative emissions system based on the adjusted one or more pressure thresholds.
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Abstract
Methods and systems are provided for increasing the robustness of engine off natural vacuum testing. In one example, following an engine-off event, a heat rejection inference is determined, and further adjusted based on a fuel level and ambient temperature. In this way, an evaporative emissions system leak test may be enabled under conditions where the leak test may otherwise not be executed, thus increasing opportunities for evaporative emissions system leak detection and correspondingly reducing bleed emissions.
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11 Claims
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1. A method for an evaporative emissions system, comprising:
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adjusting a threshold for an evaporative emissions leak test entry condition that comprises an engine heat rejection inference for an engine run time duration, based on at least a fuel level; responsive to the engine heat rejection inference being greater than the adjusted threshold, adjusting one or more pressure thresholds for an evaporative emissions leak test based on the engine heat rejection inference; and indicating degradation of the evaporative emissions system based on the adjusted one or more pressure thresholds. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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