[Diy_efi] Donegan ECU

Fri Jan 5 19:12:22 UTC 2007

Well - I was thinking 'simpler' - ie with injectors of X capacity
subtracting 5-10% of pressure or adding that same would provide a bit of
tuning capacity. A CPU and pressure sensor and PWM pump control can
likely beat the pants off a mechanical regulator - but that is my thesis
and I can certainly be persuaded :-) 

On Fri, 2007-01-05 at 18:58 +0000, John Gross wrote:
> I would say that if you're talking about doing PWM control of the fuel pump, 
> and controlling it based on fuel demand from the engine, you need to make 
> sure that the software side of the ECU will allow for quite of bit of 
> adjustability in the acceleration enrichment.  If you wait for either a 
> specific TPS or a dTPS in order to speed up the pump, if you don't have 
> enough adjustability in the accel enrichment, you'll find the engine flat on 
> it's face during tip in.  Remember that from the time the TPS registers a 
> certain delta and the pump begins to speed up, the entire fuel system has to 
> catch up.  You might be surprised by how quickly you'll drop pressure at the 
> injectors if the pump flow is insufficient.
> 
> John
> former Rolex DP Engine Tuner
> 
> 
> >From: "Steven P. Donegan" <donegan at donegan.org>
> >Reply-To: diy_efi at diy-efi.org
> >To: diy_efi at diy-efi.org
> >Subject: Re: [Diy_efi] Donegan ECU
> >Date: Fri, 05 Jan 2007 10:45:26 -0800
> >
> >And BTW my Mustang has a ~300 lph pump in it now (Holley Black
> >professional model) :-) A4 4 bolt mains block at 4.0 bore, 342 cubic
> >inches with a nascar stroker crank, 8:1 CR and 15lbs of B&M Roots style
> >blower - and of course it's not street legal here in the peoples
> >republic of CA... Will likely yank the engine and put it in something
> >pre-1972 so I can daily drive it again...
> >
> >On Fri, 2007-01-05 at 12:26 -0600, cobraman at insightbb.com wrote:
> > > I would like to see a PWM controller with a different purpose - say a 2 
> >speed version - then you could use a 1000 HP pump on the street w/o beating 
> >the fuel until it boils. Run the pump, with a regulator, at say 50 lph 
> >until full throttle or boost starts, then kick it into high......  just 
> >food for thought.  TomS
> > >
> > > ----- Original Message -----
> > > From: "Steven P. Donegan" <donegan at donegan.org>
> > > Date: Thursday, January 4, 2007 12:41
> > > Subject: Re: [Diy_efi] Donegan ECU
> > > To: diy_efi at diy-efi.org
> > >
> > > > Well - for track days I simply put dry ice in my fuel cold-can
> > > > thing -
> > > > that solves most vapor-lock style problems and lasts for a
> > > > couple of
> > > > hours. Simple low-tech solution to that problem. Given the lack of
> > > > response to my original posting I believe providing PWM fuel pump
> > > > control and support for a fuel pressure sensor is useful.
> > > >
> > > > Given that I normally run at Willow Springs or Buttonwillow
> > > > during the
> > > > winter months temps are not normally a factor anyway.
> > > >
> > > > On Thu, 2007-01-04 at 12:23 -0600, cobraman at insightbb.com wrote:
> > > > > 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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