[Bulk] Re: [Diy_efi] Donegan ECU

[Steven P. Donegan]

Well, since I am asking for feedback you can call it ugly if you
wish :-) For me doing just about anything in electronics and software is
far easier than doing it in metal (and I am a fully qualified machinist
as well as an electronics/software dude). Given this will require one
more mostly passive input conditioning circuit and one PWM output
circuit I may add it on general principles. And thank you for the
feedback!

On Thu, 2007-01-04 at 18:37 -0700, Tom Visel wrote:
> It's trading mechanical complication for electronic complication.  
> Mechanical fuel pressure regulators are a mature technology, and the 
> math for injectors that have manifold-referenced fuel pressure is 
> simpler than that for injectors with static pressure, or for 
> computer-controlled feedback-requiring variable pressure systems.  Also, 
> anything with the pressure control at/near the tank is going to have 
> hysteresis problems which will tend to minimize the gains that might 
> have been found by the increased complexity.
> 
> My vote is no, but it's not my baby to call ugly or not.
> 
> TomV
> 
> 
> Steven P. Donegan wrote:
> 
> >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!
> >
> >On Fri, 2007-01-05 at 08:00 +0900, Bernd Felsche wrote:
> >  
> >
> >>On Friday 05 January 2007 00:57, Steven P. Donegan wrote:
> >>    
> >>
> >>>I had not thought of fuel temp at all - every vehicle I drive
> >>>would consume the gas in the rails well before it got warm :-)
> >>>However this does raise a point - perhaps my ECM/PCM/EFI computer
> >>>needs a way to open a fuel return line and to sense fuel temp in
> >>>the rails? Any ideas on how useful that would be in the 'real
> >>>world' anyone?
> >>>      
> >>>
> >>Superflous if you're running in closed-loop; which you would be if
> >>the fuel rail was warm enough to make a difference.
> >>
> >>If the temperature in the fuel rail is a problem, then a
> >>recirculating fuel pressure control system is IMNHSO a better
> >>solution. In such a system, there's always "fresh" fuel that's in
> >>excess to the amount required for injection from the tank flushing
> >>the rail(s). The fuel tank is the cooling environment for the fuel.
> >>
> >>Pressure regulation also happens at the rail(s), whereas in
> >>"dead-end" systems it's at the fuel pump, perhaps a several metres
> >>from the rail and therefore the injectors. That increases the
> >>difficulty in controlling the pressure (time delays that depend on
> >>fuel pressure and temperature); especially if it's to vary
> >>dynamically wrt manifold pressure.
> >>
> >>The ability to vary the fuel rail pressure is at least desirable to
> >>get consistent injected quantities due to a fairly constant pressure
> >>difference across the injector; between the fuel rail and the
> >>manifold where it's injecting.  Makes for simpler calculations on
> >>injected quantity.
> >>
> >>If you're stuck with a "dead-end" fuel delivery system, then you
> >>need to add a return line and a valve that vents the rail(s) back to
> >>the tank in the interval between the fuel pump running and the
> >>engine actually being started. The time delay will depend largely on
> >>the free-delivery rate of the fuel pump and the volume of the fuel
> >>rail(s). That ensures that there's "cold" fuel in the rail(s) before
> >>you start injecting it.
> >>
> >>    
> >>
> >
> >_______________________________________________
> >Diy_efi mailing list
> >Diy_efi at diy-efi.org
> >Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> >Main WWW page:  http://www.diy-efi.org/diy_efi
> >
> >
> >  
> >
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> Main WWW page:  http://www.diy-efi.org/diy_efi