Worked until nearly 11pm last night and now the 206 is pretty much buttoned back up, first turn of the key was about 10.48pm and after cranking for 10 seconds to purge the fuel lines/build oil pressure she burst into life and settled into running nicely and fault free (still need to run a planet session to clear the GP code, but it's gone back to a "pending" with no EML after a few startups at least).
What a palaver though over a simple glow plug failure, only plus side being that I spotted the pitted camshaft and replaced that before it became a confusing injector correction code in future. I daresay I will seriously consider removing and cleaning the GP's at service time in future to prevent a repeat performance when the time comes to replace them again. Now it's time for poor faithful White to come into the "surgery" before she suffers a runaway! She's done a great job lasting this long with huge oil consumption & the reward for this? I plan to look around at turbo options for increasing the boost slightly, freeing up the restrictive inlet throat (at least, I think that's a restriction. it surely doesn't look good going sharply down to about half the ID where the stub joins on), removing the AC condenser to facilitate larger IC, hard boost lines, fitting a pyrometer and drive pressure gauge to the exhaust side as well as internal boost control and gauge amongst other things.
Not really in my MO to be upgrading cars power-wise but the XUD is, IMHO, just begging for a little optimisation & 90BHP is nothing for a strong engine like it (the larger HDi series kind of shows this, if the BOL is to be believed and the bottom end is based from the XUD). Either way, I need to do some research but I imagine 110-130BHP on straight veg has to be possible reliably.