I recently bought a Citroen ZX 1.9TD and as it was very dificult to start in the cold I replaced all glowplugs, and while I was at it replaced air, fuel, and oil filter with engine oil flush and full oil replacement. Since doing all the filter replacements the engine runs very well when started. I still have an intermittant starting problem. When it starts properly I switch on ignition, wait for the glow plug light to go out then start the car normally 1 or 2 turns of the engine. Other times I switch on ignition wait for the light to go out and turn engine maybe 20 turns, if I have not heard any sound that the engine nearly started I stop and repeat, to heat up the plugs again. If it doesn't start after 5 mins of this I give up and come back later. When I have had trouble starting it I do see lots of white smoke come out of the exhaust when the engine is almost starting, then a final plume of white smoke comes out when it actually starts.
Can anyone suggest what I need to be looking at to fix this?
Thanks for any help.