I did get a reply from Ross-tech "I'm reasonably confident that the factory repair info will tell you to adapt it using a scan tool. Does that mean the ECU won't self-adapt it? Not necessarily. It may be a situation like setting Readiness. The ECU will eventually do it on its own, but you can force it to run the tests right here, right now, with a scan tool."
Can anyone point me to where the FSM describes the need to adapt the EGR using a scan tool?
I just replaced the EGR (writeup to follow when I get time). 1.5 hours to remove, 2 hours to fit. That's just me, taking my time never having done this before and fitting time includes cleaning pipework and applying anti-sieze paste. Garages are having a laugh at quoting 6 hours. It isn't a difficult job at all on this vehicle.
I've been peeking at the manual for this flavour of engines and haven't seen a reference to any use of diagnostics for the EGR.
The only thing I can find with any sort of diagnostics seems to be testing the EGR system/cooler is not leaking pressure with an external device, not via an OBD connection.
5.7 Test air-tightness of the radiator for exhaust gas recirculation
Note The radiator for exhaust gas recirculation generates a pressure
of 0.05 MPa (0.5 bar) on the exhaust side. The pressure in this
case is measured in the cooling system.
Charge air system tester , e.g. -V.A.G 1687- Adapter , e.g. -V.A.G 1687/11-
Adapter , e.g. -V.A.G 1687/15-
Adapter , e.g. -V.A.G 1687/16-
Y distributor , e.g. -VAS 691 005/1-
Adapter , e.g. -VAS 691 005/5-
Turbocharger tester - V.A.G 1397A
Thanks, that is helpful and puts my mind at ease. I did go through the process described for the 2L engine when fitting a new EGR that involves turning the ignition on and off but not starting the car, then when the EGR water pump has stopped running start the engine and let it idle for a minute. I went out for a 40 mile run and the car is transformed (and no errors). Low-end torque improvement is really noticeable and acceleration vastly improved. My wife took the car out this morning and when she got back the first thing she said was "That car is astonishing".
The old EGR valve cooler was almost completely blocked and the bearing/cam was binding in three places. Still, for 186,000 miles I was expecting the valve chamber to be full of carbon and it was fairly clean. I never expected though that just replacing the valve would give such a drastic improvement.