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BETTER LOCATE EVAP LEAKS WITH ONBOARD TESTING

IP.com Disclosure Number: IPCOM000234690D
Publication Date: 2014-Jan-28
Document File: 1 page(s) / 223K

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The IP.com Prior Art Database

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BETTER LOCATE EVAP LEAKS WITH ONBOARD TESTING

Vehicles sold in North America are required to perform Evap Leak Diagnostics. For federal states, a leak size of 0.04" needs to be detected. Most OEMs perform the 0.04" leak detection in a vehicle moving condition. Typically, engine vacuum is used to evacuate the Evap system and bleedup analysis yields leak results. For green states, a leak size of 0.02" needs to be detected. Natural vacuum techniques after key off are typically used for 0.02" leak detection. If a leak is found with a natural vacuum technique, a diagnostic trouble code (DTC) P0456 is set. However, if the leak is at the CPV, then a different DTC (P1450) should be set. A P1450 diagnostic typically monitors for vacuum growth in a sealed Evap system with CPV commanded off. Currently, strategies tend to lump a leaky CPV into the P0456 bin and this makes the troubleshooting of the leak at the dealership more difficult. Some CPVs are directly mounted to the engine and a smoke tester may not implicate a leaky CPV. A better method is needed to pinpoint the leak in the Evap system and set the proper DTC if the CPV is the leaky component.

Method

The idea of the invention is to help arbitrate the root cause of the P0456 code through onboard diagnostics as opposed to time-consuming and expensive dealership off-board diagnostics such as a smoke tester. The novelty is when a P0456 failure condition is identified, at the next vehicle key on, a P1450 leaky CPV diagno...