Why cold start?

[e_lunatic]

Originally Posted by Tcoat

The high idle, rich mixture, cold start process has existed since about the Model A. It just used to be done with a choke instead of a computer. Cold start high idle is about more than just heating up the cats. It is also about building oil pressure and reaching proper operating temperature more efficiently.

isn't the "cold start" only about a minute anyway? or does it need to reach a certain temp before going to a normal run type?

[Tcoat]

Originally Posted by e_lunatic

isn't the "cold start" only about a minute anyway? or does it need to reach a certain temp before going to a normal run type?

The old carburetor ones were probably about a minute. Can’t say I ever timed it. The automatic chokes usually opened as soon as you started driving or even gave it a shot of gas. Modern tunes may go to a certain temperature to heat the cats but again I never really pay much attention. It just simply something cars have always done. Well cars that were running properly at any rate. There was nothing worse than a choke that wouldn’t close when it was cold unless it was one that wouldn’t open when the engine warmed up!

[tomm.brz]

anyway, our car gives a short burst of rich shot at the very beginning but then it targets a lean afr of 15.7 afr or around it