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An Onboard Method to Mitigate Very Small Evap Leaks in Start/Stop and HEV Vehicles Disclosure Number: IPCOM000240776D
Publication Date: 2015-Feb-27
Document File: 1 page(s) / 257K

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The Prior Art Database

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An Onboard Method to Mitigate Very Small Evap Leaks in Start/Stop and HEV Vehicles

Vehicles sold in North America are required to perform Evap leak detection as part of OBDII requirements. Green states required to monitor for 0.02" leaks as part of the Clean Air Act Section 177. (CAA) IN MY2017, all states have to perform 0.02" leak tests.Various methods are used to detect small leaks in Evap systems. Natural vacuum as well as active pumps are the most common.Once a small leak is detected, diagnostic trouble code P0456 sets. Some percentage of Evap small leaks emanate from the assembly process. As the Evap lines are connected in the assembly plant, rolled seals or slight contaminant on a seal can cause small Evap leaks.Note that the Evap monitor does not typically execute inside the assembly plant since it takes too long at End Of Line stations. If a 0.02" leak exists, it is likely show up in customer usage at low miles in service.


With start/stop and HEVs vehicles, there is a valve that isolates the fuel tank from the canister side of the Evap system. Valve is called either a VBV or FTIV. With VBV/FTIV present, it is possible to isolate the leak in the system to the fuel tank side or canister side. This method resolves a small leak on the canister side by introducing massive amount of engine manifold vacuum to compress the canister side lines and quick connections. VBV must be closed as to not damage the fuel tank. Engine vacuum is typically large at...