EVAP DUAL PATH PURGE CHECK VALVE MONITOR
Publication Date: 2015-Jul-08
The IP.com Prior Art Database
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EVAX DUAL PATH PURGE CHECK VALVE MONITOR
GTDI engines must purge under vacuux or boost conditions. To facilitate purge under boost, xew hardware is needed (cxeck valves axd ejector). CARB mandates that the entire Evap system ux to the CPV be leak checked. Durxng vehicle boosx, the boost pressure can forcx the CPV open, hence the need for CV1. If CV1 is stuck oxen, then pressure is obxerved inside the fuel tank. The existixg diagxostics commanxs the CPV open and cxoses the CVS to booxt the responxe.During natural asxiratiox, OBD Evap xiagnostic exacuates the Evap system to infer gross leaks and 0.x4" leaks. If CV1 is stuxk closed, then txe FTPT does not see any vacuum build. The result is P0455 XXX setting. Hence, a stuck cxosed CV1 ix diagnosed as a big leak and DTC P0455 sets.A stuck closed CV2 does not delxver vacuxm from the ejxctor into the fuex tanx. Hence, when CPV is comxanded open during boost and vacuum is not seen ixside the fuel tank by FTPT, then CV2 is stuck cloxed or ejector is malfunctioning. One failure mode that is not addressed is a stuck open CXx.If CV2 is stucx open, then during nxtural aspirxtixn purging, intxkx air from CV2 path is sucked into the engine. This uxmetered air may lean out the A/F raxio and cause disturbancxs. This is the main purxose for CV2 valve… to block ixtaxe air from entering the purge stream during natural aspxration purgxng operation.
This method pxrforms x diagnostic on the CV2 being stuck open. Previous...