Hi,

In reading your posts for entertainment and wonderments that seem to abound around these cars I would say you are definitely finding an issue with the vapor capture system.
I snoop around on other tabs here on BB anymore because not only did the 240s have less gadgetry but there’s a lot less of them on the road today. 🙁. Entertainment is entertainment, when I don’t need a high level of it. 🥴

I was thinking that there must be a bad valve on top of the absorption canister that connects the tank and intake manifold together. At least there is one on the 240s anyway.
They can get dirty and not shut or the hose up to the intake rots away down below where you cannot see it. Of course it’s after many years. I had to dip one into denatured alcohol to fix it but they didn’t have a big problem unless you found your hose rotten.😳

Another thought too is that you may have some water in the fuel tank. That stuff will lay on the bottom of the tank after settling. You gas up and it becomes stirred up and pumped.
In carbureted engines that water acts like a steel ball in the jets.
On fuel injected ones it gets blasted on through but it will not atomize or burn.
So think about the possibility of it.

Denatured alcohol or a can Dry Gas (more expensive) might be a solution or not buying gas only in one station. Buy gas from ones with lots of business so it fresh and the tanks are monitored more often due to the volumes.
When I grew up I stuck a long pole into the tank with some goop on the end of it. If it ever changed color we had water from condensation so we never let the tanks get below a certain level.
I guess a special gas pumper had to come or the tanks got yanked. You use to see a lot of that back when they were steel.
It can still happen since they are moving some moisturized air along with those vapors from near empty fuel tanks, daily.
Good things have been happening for our fuel supplies over the years.

Here is Something to consider in all of your evaluations.
It is that in most states now the fueling stations use gas tank vapor catching devices on the hose to your tank.
They should allow flow back from up those agitated fuel vapors and put them back underground.
From there it condenses back into a liquid upon hitting that large mass of cooler gasoline in the ground. This way they sell it back to someone else. Someone has to pay for this environmental service, as it’s called.

I was thinking that if you fill up at the same station all the time, that maybe, their system is not working correctly and that is overwhelming your evaporative system.

When I fill a gas can I top off the can to the higher end by just pulling back the elephant sized contraption to see around it. As long as it’s back a bit the nozzle will still pump.
You might just fill the tank one time with your finger under the lip to let it vent more freely.

Have you had the same problem when using any other different service station? It’s a thought anyway?

In any case, I think you are correct in your assessment of excessive vapors or air coming in whether or not ECU calls for the vapors at idle.
If it a stuck valve or a split hose that could leave a pathway open for flow of vapors or raw fuel to enter then all of that will get sucked into the engine.
On the 240s the little valve was vacuum activated.
But on these newer vehicles, I could see where they might be using a more tricky-dicky bunch of hocus focus.
That could explain the delay each time until it clears the fuel vapor line from the tank.

As far as the other codes, I’m like Shultz on Hogans Heroes “I know nothing!”🙄

Phil