[Diy_efi] Donegan ECU

[Steve Ravet]

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Steven P. Donegan
> Sent: Thursday, January 04, 2007 6:49 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Donegan ECU
> 
> I can't quite read this as a yes or a no to fuel pump 
> pressure control - can you give me a binary response :-)
> 
> I.E. does fuel pressure sensing/fuel pump control make sense 
> for an EFI system or not.
> 
> Thanks!

For big engines maybe, as it would increase the dynamic range of the
injector for engines that need it.  ie a big injector sized to be at 80%
duty cycle at max HP may flow too much fuel at it's minimum pulse width
at idle, so you could lower the fuel pressure to reduce the fuel
delivered.  But how many engines need that?

I don't think the delay from back to front of the car is anything to
worry about, assuming no leaks or bubbles the increase in pressure will
propagate from the pump to the injectors at the speed of sound.  Maybe
the inertia of fuel in the line ahead of the pump will reduce delivery
slightly during acceleration but that doesn't seem like much of a
problem either.

Does the vapor problem just mean extended cranking while the vapor works
it's way out of the lines through the injectors, or is it a bigger
problem than that?

--steve