OKaay for anyone listening. Theory number.....4??
Re; the EGR Bypass Circuit. The Bypass valve is used for either Cooling or providing direct hot exhaust gasses to quickly warm the Cat and Engine etc. upon Start-up. When the vehicle reaches Operating Temp, the Valve is Closed. From what I can muster, the valve is only used for Cold Start AND DPF Regen. It is not used at any other time. Therefore, regardless of the readings of 100% in Red, the action of the bypass Valve is working based upon the observation of it i.e From Cold start the vacuum is activated and the valve is moved. When it is warm the valve is released allowing constant cooled air to be used when the ECU determines the Fuel/Air Mixture based upon Throttle position.
The Idea of the Red 100% reading may be a Red Herring and another issue in it's own right, but I no longer think it has anything to do with my symptoms. On the other hand, the EGR Valve readings are in sync, from Instruction to Position, however even though the readings may be good, does that translate to physical movement of the valve, or could the valve be working but after the valve the airflow is restricted?
The van drives as if it is suffocating. The van drives as if it's towing. The van drives erratically. Still no smoke, still no codes, but it's misfiring and lumpy and slow. Turbo or effect of is inconsistent.
I took off the Air Doser today and used a mirror to look up inside it. I could see the entrance to the Manifold and the small flexi hose from the EGR into the manifold was covered in Carbon, but it looked Dry, not sticky; It looked like soot more than gunk.
I'll strip it tomorrow and see if it improves. I still need to know how to drain the coolant?