[Diy_efi] Donegan ECU

[cobraman at insightbb.com]

My "Edelbrick" ProFlow has fuel pressure controlled with engine vacuum. On track sessions on very hot days, the fuel in the rails will boil under hard braking - accelerator closed (low fuel pressure). When you finally step on it (52 psi), nothing happens until the vapor "recirculates" or is expelled.  Usually takes a second or so.  I don't think dead heading would do any better - probably just need to keep a constant fuel pressure. 
IMHO, hot fuel should give better economy - easier to vaporize - for those green members.  TomS







ld
> 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?
> 
> On Thu, 2007-01-04 at 14:56 +0800, Mike wrote:
> > Isnt one of the main needs for fuel return the fact the fuel 
> is heated quite a
> > bit in the fuel rail whilst its waiting for injection ?
> > 
> > Of course there is a commercial factor as fuel returns used to 
> be so
> > much cheaper than any electronics but getting around the fuel 
> heating etc
> > 
> > Also the issue of control feedback is an issue to avoid 
> vapourisation> during hot start, the good thing about return is 
> this can be flushed out,
> > and esp for a turbo as a pressure hold tank can "remember" the last
> > max pressure and temporarily raise the fuel rail pressure to 
> this during
> > start to avoid vapour issues... etc
> > 
> > Regards
> > 
> > Mike
> > 
> > 
> > 
> > At 07:23 AM 1/4/07, you wrote:
> > 
> > >This sounds cool...is closed loop control of fuel pressure an 
> oem feature for any new vehicles? Or just something you are 
> trying out? Are you going to use a PI controller? I am guessing 
> when you snap the throttle open the PI controller should know 
> about this quite quickly...not wait to see a drop in fuel 
> pressure? 
> > >
> > >> To add something somewhat useful to the list in this reply 
> I'll say the
> > >> Donegan ECM is coming along nicely :-) The input board is 
> going to fab
> > >> out at about 3.0 inches by 2.2 inches (exactly matching the 
> CPU board -
> > >> ARM based Steve). Inputs designed in are MAP, MAT, 
> Barometric, Coolant,
> > >> Throttle, Oil pressure/temp, 4 ea O2 sensors, Crank and Cam 
> position, 2
> > >> ea EGT sensors - well pretty much everything everyone told 
> me should be
> > >> sensor inputs. Fuel pressure input I'll put on the 'relay' 
> control board
> > >> - that will do PWM control of the fuel pump eliminating the 
> need for a
> > >> regulator or return line.
> > >> 
> > >> Happy New Year :-)
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