Won't start in ten below temp. Cranks but don't fire

Need a scan test viewing live data to see if coolant temp sensor is telling the computer exactly how cold the ambient temperature is!!... Not a parts store code reader.. A real scanner!! Computer got to know that to adjust fuel accordingly!!!.. Colder it is, more gas needed to start.. Don't have a choke anymore... One catch, needs to be done on cold engine.. before ever starting!!