It is indeed not the easiest point to prove, but be assured you made have your argument very well in both posts. Let us not lose sight of he fact that this is a forum and things could be very different if were both standing in front of the car and actually having a dialogue.I assume I don't prove my point, in a very good way, in the first post, but I believe that I made a good argument after that.
Extremely unlikely, Agreed. However could it be that this particular cylinder is Good but the other 3 are slightly and evenly lower on compression and ECU has added fuel to its limit trying to balance the engine to a point now where it has no choice but to subtract fuel from the stronger one ? As you clearly have stated, No Smooth Running PID's for this Engine !!! ???Could the extra fuel be oil in the cylinder? Fed in a very regular and constant way, not revving the engine? I really don't think so...
Am I just being pedantic & awkward or is it that I have seen my fair share of Control Strategies that have blown me away ? Messed with my mental health ? Nothing can surprise me anymore with these Demons and Devils that you call cars.
Again something I have never seen and the odds are against it can only be guess.
Just to keep our feet firmly on the ground, this debate is not about fixing the car, you have achieved that in a proper professional manner and credit to you for that.
More so I see it as bouncing to and fro with our theories and experience, keeping that grey matter stimulated, learning something that will trigger a fix in the future.
I have taken on board everything in this thread and don't be surprised if I look back on it sometime soon faced with a similar fault you have cured.
As always, I'm happy to be corrected, makes for good learning, so thanks for providing the challenges.