So I am fighting an issue with my jeep JKU that has a Gen V swap in it. It turns out that my vent solenoid was fed by a ref voltage instead of 12v from day one. Now its 2+ years later I realize this and fix it. Now I am getting a P0446 which is vent valve malfunction. Vent valve and purge are both brand new. My question is this ?. I read an article stating that the EVAP self test cant run and/or pass properly if the fuel tank level isn't reporting correctly. My conversion company has set my fuel tank level to a constant 61%. Same article mentioned that tank pressure is affected by ambient temp, which in turn will affect tank EVAP venting and self testing. Does this make sense?
From day one, I have gotten quite poor fuel economy (11-12). A Silverado drivetrain in a jeep (lighter) I'd expect to see at least 16. Also I have always had side effect results of over fueling. Some odors, inappropriate cat temps, etc... btw, my cat temps did improve when I got 12v going to the vent valve in stead of 5v. Biggest complaint for over a year now is low idle stalling.... rolling to a stop, or coasting down the driveway the idle just drops out from under me.