Thanks for the tips Victor. Yes I have to get some leaning provisions
  in there. It is such a modular design I am thinking of doing a
  mass air flow module or a MAP sensor module in place of the
  slide throttle sensor. Just unplug it and plug in something else.

  Another huge advantage of this approach is the math coprocessors
  built into these chips that do floating point math in no time :)

  Something you don't find in most EFI single chip computers.

  ---------------------------------------------------------

  One use of the floating point math capabilities is to display
  Gallons Per Second or GPM or GPH or all three on the LCD.
  Handy when you get low on gas.

  The computer knows the RPM and it knows the pules width.
  fuel burn is therefor: RPM X pulse width X constant.

  With another A to D connected to the air speed pito
  tube pressure sensor MPG could be displayed. Also total fuel burned.

  The possibilities are endless when one can make floating point
  calculations
  in 5 microseconds. It is only limited by the number of sensors you want
  to install.

  The additional programing is trivial:

  PRINT "Gallons per Hour ="; RPM * Pulse-Width * xxxxx

  xxxxx is a constant that gives GPH.

  Paul Lamar

Even better would be ground speed off a GPS. It must be possible for someone
bright like you.

John
PS Hey maybe feed it back to the GPS and have it plot a range circle.

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No problem o. We have an RS232 and many GPS's output position once a second
in NEMA 0183 format through an RS2332. Here is a BASIC program I wrote back in the late
1980's showing the position of all visible satellites. Straight out of the screen
is straight up. The top of the screen is due north. They plot their position on
the screen as they move.

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I discovered this National Semi A to D chip that will give us eight
channels of A to D using just one modern bi directional printer port.
That should cover MAP and water temp as well as six other measurements.
Along with the full floating point this will make a comprehensive
engine monitoring and data acq. system. The VIA board I have has the bi/di
printer port as does most of the mother boards now on the market.

How this works is the Power Basic sets a bit that tells the chip it is
going to select one of eight sensors. Then it waits 40 microseconds
while the A to D chip does it's thing, resets the bit  and then reads
the digital value of the selected sensor over the same eight wires
it selected the sensor. Clever :)

The board will just plug into the printer port as it has only one
chip on it. It is rather self contained.

BTW I have updated the web site so you can read the background on this
approach.

http://www.rotaryeng.net/simple-cheap-555.html

Unfortunately the single channel A to D chip shown on the web
site is already obsolete. This project is rapidly turning into
a full time job :) It is worth it as tiny PC mother boards will
continue to get cheaper and more powerful.

Paul Lamar