I think the adaptation you are struggling with is CUR_VCV_BAS_AD_VAR_2_ADD
The control of the VCV varies but during WOT it operates in "MFP" control. I assume that's mass fuel pressure, I know it looks at the fuel demand but also has a PID that control on the rail pressure I think.
MFP control is constructed of 2 stages of control. It has a component that looks at the target fuel pressure and the actual and generates a kind of precontrol value.
It also has a base component which looks at the calculated fuel mass. That calculation relies on the actual load and corrects based on the trim values.
Interesting. WOT seems fine for me, but I guess that makes sense on what you found.
A couple other updates from my end. I pursued my theory, make some educated guesses, and flashed a new set of the 2 VCV tables. After 2 long trips, no more cycles at idle post long drive (so far). I will continue to monitor, but the exact same drive cycle gave the behavior this morning before the change, and it happened pretty much 100% of the time after any highway drive. I was watching rail pressure at cruise, idle, in gear coast and more or less whenever I could and seems like it is more stable with operation in a tighter range. Just from looking at the supplied tables, they seem focused on providing more fuel on the top end versus a holistic redesign across all conditions.
A couple other cases that I observed with the tables provided by Spool that I found odd were:
(1) I have a MT. In gear with 0 throttle, the rail pressure would 'race' a little up from ~725psi to maybe 1000 and bounce around a little until throttle was reapplied. After my changes, it seems to only go up to ~875 or so and sticks there. I am giving it less DC at 0 L/H of flow, which has a value of 1.20A stock. I am going to drop the value in this cell at my next test to maybe to 1.1A. I am assuming that in gear but coasting would still target 5MPa/725psi on the high pressure side, but it seems like it does.
(2) After coming off cruise and applying low throttle, I would see dips in rail pressure down in the 300-450psi range. Eventually it would catch back up. In my last drive cycle, the behavior was still there, but was confined to more in the 575psi range and didnt go lower.
how is the adaption you mentioned (CUR_VCV_BAS_AD_VAR_2_ADD) applied? Is it truly a 'globally applied' value, for example +/- some % DC adjustment to the VCV itself regardless if at idle, cruise, part throttle acceleration - basically anything other than at WOT (since that is MFP mode?).