I think you guys are rushing to find problems that don't really exist.

Many diesel engines require a touch of throttle to start. My truck has always required a bit of throttle to start, winter or summer. It requires a touch more in winter.

Any diesel with a preheat system (grids or glow plugs) should not crank beyond 3 seconds. You have blown out any warmed air and are trying to light a cold engine. That does not work on a compression ignition engine. If it fails to start, cycle the grid heaters again and give it some fuel on the restart.

BTW, cold to an engine is anything below 40°F.