RPM independence

[Todd....!!]

Howard the article is in the May 99 issue of GM High-Tech Performance

And the brand that uses Volumetric and other formulae instead of look-up
tables is known as Electromotive....  Probably heard of em?  HAHA!??

Keep me informed of your progress in this matter!

LATER!

Todd....!!

Howard Wilkinson wrote:
> 
> Todd:
>     I would be very interested in reading the article you mentioned.
> Please let me know if you find it.
>     My basic thought here is to emulate the working of the Bosch
> mechanical CIS fuel injection system electronically which would allow
> it to be modulated by feedback, but still yield a system simple enough
> to be operated by a very low cost controller.  Injector timing is
> irrelevant, therefore injector firing rate is also irrelevant within
> the range above engine RPM.
>     Perhaps mathematical formulae are not adequate to control fuel
> delivery.... maybe lookup tables are necessary.  The Bosch mechanical
> system used a shaped MAF to keep fuel flow which was mechanically
> controlled in line with the motion of the MAF actuator arm.  This put
> the mathematical calculation into the profile of the MAF throat which
> was in effect a computer (a mechanical computer).  It took far more
> intelligence in my opinion to design this one part than to program
> look up tables which can be done by trial and error, or by a simple
> feedback system.  I believe I could sit here and flow chart out and
> write a program to generate the lookup tables based on feedback, and
> minimal programmer input.  I'm just looking at different possible
> approaches to the problem of managing fuel delivery via computer.
>                                         H.W.
> 
> -----Original Message-----
> From: Todd....!! <atc347 at c-com.net>
> To: diy_efi at efi332.eng.ohio-state.edu
> <diy_efi at efi332.eng.ohio-state.edu>
> Date: Tuesday, May 11, 1999 1:15 PM
> Subject: Re: RPM independence
> 
> >Hello Howard,
> >
> >your theory is TOTALLY GREAT and acceptable, and a system has alread
> >ybeen created, produced, and marketed, and it's gone over wiht a
> pretty
> >good fine tooth comb within on eof the laterChecvy Hi po mags dealing
> >with all of the diff types, makes, and brands of FI for just about
> any
> >type engine!
> >
> >Will get the name of the mag, I know you already know about the mag,
> >just maybe not about the article(s) within this specific issue?
> >
> >But the basic function of the type system I believe you are referring
> to
> >is based upon the use of formulas instead of tables... I think you
> are
> >right in line witht the way this REALLY advanced system is designed
> to
> >function!
> >
> >Will post details later, (mag's at home)!
> >
> >LATER!
> >
> >Todd....!!
> >
> >Howard Wilkinson wrote:
> >>
> >> I have given more than a little thought to the possibility of an
> EFI
> >> system that operated completely independently of engine RPM.  The
> idea
> >> being that as the injectors are batch fired anyway, the timing is
> >> irrelevant so long as the injectors fire at engine RPM or more.
> >>     Such a system could be almost entirely MAF based.  The
> injectors
> >> would begin at a very short pulse width, and simply increase pulse
> >> rate up to a set pulse rate where width would be increased
> thereafter.
> >> Such a system could be operated based on mathematical formulae
> rather
> >> than on look up tables.  A simple equation based on ECT could
> modify
> >> the result for cold operation, and a TPS modifier would give
> >> accelerator pump effect.  Map should not be necessary as air
> density
> >> should directly effect MAF output.  An O2 loop would handle minor
> >> dicrepancies.
> >>     A lot of the complexity of the common EFI systems comes from
> the
> >> desire to fire the injectors once per revolution.  Because of RPM
> >> dependence, the MAP, MAF, & TPS outputs are meaningful only in the
> >> context of RPM.  Total fuel delivery per unit time is only directly
> >> related to MAF.... It is not closely related to RPM, Throttle
> >> Position, or Vacuum individually as it is to MAF.  The MAF tells us
> >> how much fuel we must deliver per unit time, but the system must
> then
> >> work out the pulse rate based on RPM, and pulse width for that rate
> to
> >> achieve the desired delivery per unit time.
> >>     If we know that x amount of fuel is delivered at Y pulse width
> per
> >> pulse, then it becomes a simple matter to determine how many pulses
> >> per unit time are required to deliver that amount of fuel.  At some
> >> point pulse rate reaches a max practical limit, and at that point
> >> pulse rate can become constant, and pulse width may be modified
> above
> >> that point to control fuel delivery.  The fewer factors you are
> >> changing the simple the program becomes.
> >>     Perhaps this is a simple minded vew of the process, but then
> I'm a
> >> simple minded sort of guy.... I am of the "KISS" school of thought.
> >>                                 H.W.
> >
> >
> >