I found out that VBSOL refers to Power source for solenoid valves.
I had P1456 when this saga began, and that changed to P1457 when I replaced the two-way valve.
The P1457 became very predictable. Drive the car twice, MIL comes on and code is P1457. I decided to remove my fuel cap before starting my engine this morning. The whoosh of air (or fuel vapor) that I heard when opening the cap made it quite clear that it had been air tight. Should it have been? I could not tell if the whoosh was releasing vapor pressure, or if perhaps I had a vacuum inside the tank due to lower temperature overnight. I thought the Canister Vent Valve should have been open while the car was parked overnight, and the two-way valve should have been allowing fuel vapor into the canister while the canister vent should have let air escape to the environment. It was clear that there was either pressure or vacuum
Given how predictable getting a P1457 had become, I wondered if I could get the P1456 back by simply storing the gas cap in the trunk and driving. I was surprised to find that the MIL did not come back after several drives, but I do have a pending P1457.
In the course of the P1457 saga, I noticed that I started getting OBDII Mode $06 CID $01 TID $2E values of 0, where the minimum passing value is 8. I found that $06 CID $01 TID $2E is defined as EVAP_PCT, which elsewhere I found described as follows: "Shows the status of the Evaporative Purge Control Valve between 0% (no flow) and 100% (max. flow, max. duty cycle)."
That suggests that my purge control valve has a duty cycle of 0%, so it is never being commanded to open. Since that is the only failure indication I have other than the P1457, it seems fair to assume they are related.
From yet another source I found this: "EVAP PURGE = EVAP_PCT: This parameter is displayed as a percentage and is normalized for all types of purge systems. EVAP Purge Control commanded OFF will display 0% and EVAP Purge Control commanded fully open will display 100%. This is an important parameter to check if the vehicle is having fuel trim problems. Fuel trim readings may be abnormal, due to normal purge operation. To eliminate EVAP Purge as a potential contributor to a fuel trim problem, block the purge valve inlet to the intake manifold, then recheck fuel trim."
I do not have any indication of a fuel trim problem, but I haven t been looking for that. I do think my mileage is lower than in the past, and I did find fuel in the old two-way valve that I replaced.
Here is some wild speculation that fits the facts. Maybe I overfilled my fuel tank and that caused fuel to make it to the two-way valve. That valve is designed to function with air and fuel vapor, but not with liquid gasoline. Maybe I have liquid fuel trapped between the tank and the two-way valve, and maybe driving without the cap for a day helped some of that dry out. I put the cap back on, but will remove it again in the morning. I will try to figure out if I have pressure or vacuum. I will drive another day with the cap off.
Or maybe I had a large leak that was fixed when I replaced the two-way valve, and now I have a small leak. Perhaps it is time to obtain a smoke machine and figure out how to use it. Is there a smart choice from tools on the market? Where would I find the green cap service port on my car?
Images (Click to enlarge)
Tuesday, September 18th, 2018 AT 7:39 PM