Programming in Cold Weather

[Power Hungry]

Just for reference, what gassers call "timing" is called "start of injection" or SOI on a diesel. This is ROUGHLY the same comparison although spark timing on a gas is more of an instant reaction while a diesel has a small delay between the time the fuel is injected and the time it actually starts to burn. This just semantics, though.

Anyway, the reason for the extremely advanced timing in cold weather is because the diesel fuel burns SO SLOWLY at those temps that it can take as much as 20 or 30 degrees more timing just to keep the engine running. Of course, as the engine warms up, the timing will back down significantly.

Diesels also monitor Intake Air Temp since colder air needs to be heated a bit before entering the cylinder. This is what glow plugs and intake air heaters are for. Diesels also use the Intake Air Temp to advance the SOI so the engine can run properly. This is the reason that even with the engine fully warm, it is always a little "louder" in the winter than it is in the summer.

Hope this helps.