If the smoke is unburnt diesel it will have a distinctive 'sweet' smell but I can't see why if the injectors are OK unless the fuel is being inject in at the wrong time - which would be a management issue although I have never heard of it happening. Normally the only other cause of smoke after idling is oil running down the valve guides but that's usually blue.

Thanks for your answers, I saw another diesel mechanic today and we've confirmed that the smoke is actually blue and smells of oil, on the further investigation the turbo rotor has play in it and there was a lot of oil in the pipes so we're going to try a new turbo and hope this cures it.

Thanks again, John.

Strange as you did say in your first post it had been run with the turbo disconnected !

I trust it has the right dip stick in it ? They are prone to snapping on this model and often get replaced with ones from breakers yards! I have seen wrong dip sticks fitted causing excess smoke. best to drain the oil and add measured amount then see what the dip stick reads.I can remeber having a Renault Fuego in for bad smoking and that had the wrong stick and smoething like 2/3 pints of oil too much !