[Spridgets] EFI breakthrough

Glen Byrns grbyrns at ucdavis.edu
Mon Oct 29 09:33:54 MST 2007


This weekend was the breakthrough. I got all the fuel plumbing squared away,
return line, pressure regulator, pump wiring etc. and couldn't get it to
start.  No fuel pressure.  Backwards wiring on the fuel pump...DOH!!  Switched
wires and it fires up!!

I still need to adjust the air bleed on the Ford fast idle valve to produce a
slower "fast idle" (just make another gasket with a smaller hole punched in
the gasket) and adjust all the values in the fueling table under load
conditions as part of the complete tune-up, but the initial table works well
enough to take the car out and around the neighborhood.

This morning before work, after all yesterday's fiddling about, I tried to
start it up cold.  It worked!  From here on out, its just one drive after
another with an eye on the laptop screen and slight tweaks of the fuel table.
This baby is going to Missouri!  Once the fuel is dialed in I'll activate the
ignition circuits and give spark control over to the computer as well. I knew
I'd want timing control so I built in all the optional circuits when I
initially assembled the Megasquirt. Then I'll have the much desired "timing
retard on boost" that makes 91 octane pump gas and turbos get along.

I've spent some time thinking about the ramifications of altering a simple
road-repairable car to black-box control and how far it is from the original
Sprite experience.  In the end, since my car was so far down the "hot-rod"
road when I got it, originality was never really a part of this particular
car's history.  Speaking to the old friend that sold me the car, I think he
would have done the same.  He was the one who hung the turbo on it in the
first place.  I'm just continuing his legacy of hot-rodding.  Since I built
every single part of the system, I should be somewhat able to fix it if
needed.  Also, if this electronic stuff doesn't fail in the first day or two,
its usually good for years.  God helpp the poor devil that gets this car after
I'm gone.  They better hope I get around to filling a notebook with notes and
part numbers and custom wiring diagrams.  Of course I'll keep the big ole 1.75
SU and manifold in a box under the bench for future whussies.

The next posting, with luck, will be a video with sound of the running motor.

Glen Byrns


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