Date:         Mon, 6 Apr 2009 22:26:51 -0700
Reply-To:     David Kao <dtkao0205@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Kao <dtkao0205@YAHOO.COM>
Subject:      Re: digifant injection
In-Reply-To:  <046501c9b727$9c2fb6b0$6401a8c0@PROSPERITY>
Content-Type: text/plain; charset=us-ascii

Yeah, it is that simple and it's an old system. It has a Z80 (or 8088)
class microprocessor with an EEPROM (or ROM) that keeps the code the
processor uses. No one needs to know what the processor do to make it
an ECU. It just works and it is that simple. Sometimes I did wonder
if the processor ever crashes and reboots like all PCs do. As long as
it is a microprocessor it has to be able to crash and reboot without
affecting the engine. Regardless it only knows two things or two dozen
of things it has to crash and reboot sometimes. When the engine hi-cups
it must be that the ECU has just crashed and rebooted...

David


--- On Mon, 4/6/09, Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM> wrote:

> From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
> Subject: Re: digifant injection
> To: vanagon@GERRY.VANAGON.COM
> Date: Monday, April 6, 2009, 7:21 PM
> things are happening fast enough, that it doesn't matter
> 'too much ' that
> each injector opening period isn't timed with the
> intake valve.
> So sure, the fuel injected 'hangs out' for a few
> milliseconds before the
> intake valve opens ......but it works well enough.
> No modern engine uses anything this crude of
> course..........the standards
> for  emissions , good drivability, power, and fuel economy
> have risen
> dramatically since .....since say, the first waterboxer
> vanagon in 1983 and
> a half.   We've come a long way from there baby .
>
> In more evolved systems...........
> called 'sequential electronic port injection', each
> injector is fired
> individually, in time with each cylinder's intake
> stroke.
> Cam and crank position sensors are needed for that .......
> not that big a deal..........I was even dreaming of
> retrofitting a Subaru
> fuel injection system to a waterboxer.
> Vanagon fuel injection is pretty crude I think.,
>
> the ECU on a waterboxer only knows two things about the
> basic engine (
> besides coolant temp, AFM input,  and that sort of thing )
> .....
> it only knows that the engine IS turning ( from the
> distributor ) and what
> the rpm is, but that's it.
> Mas crude hombre !
>
> Scott
> www.turbovans.com
>
>
> ----- Original Message -----
> From: "Allan Streib"
> <streib@CS.INDIANA.EDU>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, April 06, 2009 6:50 PM
> Subject: digifant injection
>
>
> > Another post got me curious, and I read a bit about
> how Digifant works.
> > From what I read it seems that all 4 injectors fire
> together, which
> > confuses me -- I would have guessed that each injector
> fired just as the
> > intake stroke was starting for that cylinder.  Does
> the fuel vapor just
> > sort of accumulate behind the intake valve until the
> intake stroke for
> > that cylinder?  Surely 3/4 of the injection cycles are
> not "wasted"
> > fuel??
> >
> > Allan
> > --
> > 1991 Vanagon GL