[Diy_efi] Fixed frequency PWM batch mode FI

[bcroe at juno.com]

On Sat, 24 Aug 2002 06:36:07 -0400 Dave Dahlgren <ddahlgren at snet.net>
writes:
> With AFR constant PW is exactly proportional to torque or at least 
> has been for the last 12 years I have done them..
> dave

That is true when the injection pulse is triggered by crank 
rotation.  So number of (constant width) pulses increases 
with rpm, at constant torque.  

If you fix the pulse frequency, the above statements no 
longer apply.  If rotation does not control how many pulses 
occur, then rpm will have to be a multiplier in determining 
pulse width.  This could be made to work, but I don't see 
the advantage.

The method described by Ron is quite straight forward.

Bruce Roe

> 
> Ron Schroeder wrote:
> > 
> > Hi Les,
> > 
> > Since torque is roughly proportional to fuel injected per 
> > combustion event and air is roughly proportional to MAP, 
> > the simplest first order fuel calculation is MAP times 
> > RPM.  So having injection NOT related to RPM would
> > actually make fuel calculations harder.  My first EFI was as 
> > simple as a 555 triggered by the ignition and the MAP 
> > scaled and inputed into the threshold pin.
> > 
> > Ron Schroeder

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