[Diy_efi] Timing Calculations

[TheEthereal at gmx.net]

If your trigger wheel varies the length of its output impulses w/ the speed
it turns, you could use that to exactly calculate crank speed every time you
get a trigger signal. I.e. 10 miliseconds at 1000 revs, 5 ms at 2000 revs
and so on. Most if not all trigger sensors have this feature.


> --- Urspr?ngliche Nachricht ---
> Von: Mark Higgins <nospam at higginstribe.com>
> An: diy_efi at diy-efi.org
> Betreff: Re: [Diy_efi] Timing Calculations
> Datum: Wed, 15 Jun 2005 22:57:26 -0400
> 
> Before people get off on more of a tangent with 60 tooth trigger 
> wheels.  Thanks for all the discussion and calculations.  I also want to 
> factor that all of your calculations are based on the worst case 
> scenario, that timing will come at the farthest point from the trigger 
> wheel.  Obviously the deviation from the actual and desired event time 
> will start at 0 from the trigger point and reach the greatest error just 
> before the next trigger point.
> 
> Anyway, it seems pretty obvious to me then that I should build in some 
> sort of rpm prediction calculations, possibly based on throttle (or MAP) 
> changes if I want them to be quick.  Of course, I'm more worried about 
> injector timing then ignition timing.  I can't move the injector off 
> time (or at least I shouldn't, much) which means I need to fairly 
> accurately predict the on time based on what I currently know about the 
> acceleration/deceleration, and I need to predict that on time, possible 
> most of a engine cycle ahead of the injector off time.
> 
> This means I'm going to have to sit down and seriously think about the 
> logic I'm going to use to reduce this problem as much as possible.
> 
> Thanks everyone.
> 
> Mark Higgins
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