EGOR testing

[bcroe at juno.com]

It was a really nice day today.  I went out and welded 
up a 22" extension for the 2 1/4" tail pipe on my 79
Eldorado.  That's the one with an ANALOG injection
computer.  I mounted my EGOR probe in the 
straight section, 14" from the outlet.  Did someone
say it should be 16"?  Warmed up the probe, then
started the engine.

IT WORKS!!

Sure enough, starts pretty rich, comes off choke 
closer to stoich, idles a little rich.  When the engine 
is hesitating, I see its in the red.  I wonder if its the
fuel curve or the fuel pressure; now I need to get 
that fuel pressure gauge working.

This design is running the probe internal calibration 
resistor, so it should be accurate.  The guys with
bottles of calibration gasses will need to check this.
It also has a switch to allow using air for calibration,
based on the estimate here that air looks about 
3 times as lean to the probe as 21.44:1 A/F.

Thanks to the EGOR group for supplying the info 
needed to get this rolling.  Some more testing is
in order; haven't gotten it on a carb car yet.  I got
the scope out in the car and checked a few things.
Sure enough, the extra capacitor I DID NOT put in
to stabilize the differentiator, WAS NOT stabilizing
it in some situations.  There was a trace of 12 KHZ
oscillation over in the rich area, although it didn't
really seem to bother the output which filtered it out.
Retune that a tad, but later.

After a few more trials, an easy way to build copies 
would be good.  Getting a PC board together will
be a non trivial project, the biggest item getting a 
layout and routing.  Actually making the boards 
just boils down to money.  But there are some 
offers to help, I don't know just how that will go.  
Thanks to all assistance past and future.

Bruce Roe


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