[Diy_efi] CIS EFI via Fuel Pump PWM

[Stephen Webb]

> The point was to PWM the pump and get rid of the regulator.  And the
> inertia of the pump rotor isn't affected by the length of fuel line.

I may have picked up late on this conversation, but from what I gather the
idea is to use CIS injectors and some sort of electrically controlled fuel
pressure in order to get EFI CIS, no?

Would the injetors be "pulsed" once per revolution by the fuel pressure
changes, or would the fuel pressure be a rather constant level
corresponding to load?

If it's pulsing you want, then I would agree that fuel line stretch, pump
inertia, fuel compressibility, pressure dampeners etc will make it
impossible at all but the lowest engine speeds.  (my $0.02)

If it's a smoothly varying fuel pressure with engine load, I'm not sure
how the CIS injectors will respond to that.  I know they have a low
pressure dropout point, but above that pressure I don't know how they flow
differently.  My understanding is that it's not the job of the CIS
injectors to meter the flow, just atomize it.  So reliably controlling
flow with pressure at the nozzles may not be very easy.

Why the interest in "EFI CIS"?

Don't get me wrong, I think CIS is absolutely wonderful.  I would gues
that the CIS-E Motronic system is about as much electrical control as you
are going to reasonably get.

-Steve



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