Cold starting anytime temp below about 5degrees sounds like a tractor without glowplugs working. Ford did diagnostic check when above 5 deg and found no fault codes and said if glow plugs were faulty it would show up on diagnostics, so could there be a temperature sensor or something else that could cause a relay fault or no excess fuel supply. Normal temperature starts fine, but cold I now have to rev a bit as soon as it fires or else it knocks and clatters terribly. An ideas please guys as I am tearing my hair out trying to find this fault. thanks.