engine coolant temp sensor

hello, question is how come we should add more fuel to cold engine startup this will allow more liquid into the engine and hard for it to ignite where as if it was leaner it could ignite from the easily combustable vapor form?

Hi Laith,

The extra fuel is for various reasons, to wet the port walls and valve and also that when the engine is hot the fuel vaporizes, making it easier to for combustion. When the engine is cold and fuel enters as a liquid form which is more difficult to combust so requires additional fuel to be added.

There is a great article on this below.

https://www.hpacademy.com/technical-articles/cold-starting/#why