Quote:
Originally Posted by Coupeguy2001
Everybody is going to chime in on my comment, and that's fine. Just understand that my comments come from experience, not just someone else's entries.
not to be difficult, but open loop is cold, and closed loop is warmed up. Since 2000, almost all engines use sequential fuel injection due to emissions standards and more precise fuel metering.
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oops that was me that got open v closed backwards. rookie mistake. I even proof read it before I posted. you are right.
sequential systems switch to batch over about 2500 rpm even on the most powerful processing, most detailed input systems. there just isnt enough window at that rpm to inject all that fuel in that short amount of time, even the delay of the solenoid opening has to be accounted for. The performance difference at that rpm is nonexistent with a properly designed system. Some manufacturers use sequential only for idle and warmup, when emissions are measured for credit, and switch to batch almost instantly when driving. Why try to get it all in 200 degrees (of cam) when you can get it in the 720 (of crank).
I built a fuel injection system from scratch for my engineering senior project, the high requirements for sequential injection (injector size, processor power, extra sensors) dont really help beyond a certain rpm, even though common thinking would want to believe that injecting fuel only when the valve is open is the correct way.
There is a sequential system that can work at high rpm, that can inject a large amount of fuel in a very short window, it is direct injection, and runs over 2000 psi on injectors that are as long as a ruler and inject directly to the combustion chamber. The diesel guys have been using them for years and you can have a very lean AFR without knock.
your other points are exactly correct, lots of tuning!