Thanks Brian thats interesting, I had not thought that might influece the engine smoke output so much but I supose the injector firing is crutial to good running, I looked at the plug on the head and it was bone dry ( see post 68) , but in the past there has been the dreaded wet red plug, I still spray it with brake cleaner now and again, just to get it perfectly dry.
When I bought the vehicle it had one of those clip on tune up chips fitted which was simply scotch locked onto the loom near the ECU, I took that off but it still troubles me to have the insulation on the injector leads cut and just covered up with tape. I also wondered if they did anything to the ECU setings when this was fitted and I would like to get hold of a know good, bog standard ECU map for the defender TD5 and upload it to see if that may help.
I bought a new loom from Shifty some time ago ( and I still have your old one in my garage ) I am planning to do a big engine job if I have time this summer and fitting a new loom would be part of the story, would be nice if it gets it working better again.