More DIS with 749.bin observations

[Tedscj at aol.com]

Well, I got my EPROM burner in the mail last night and have had some time to
try things out.  Unfortunately, while I learned a lot, I am now at a dead end
with no solution.

Here's what I did.
I burned a 749.bin and stuck it in my 730 with DIS.  It ran, but it ran like
crap.  It missed and sputtered and coughed.  No surprise there, since that is
what I had heard would happen.  Then I disconnected the EST BYPASS line to let
the DIS module handle the timing and dwell without interference from the ECM.
It ran pretty well, although there was very little advance.  No surprise there
either.
THEN, I made a recording of the EST Signal from the 749.bin to compare it to
the DIS EST Signal.  THEY WERE IDENTICAL.  Absolutely identical at 1200 and
3000 RPM.  They were not inverse of each other and the Dwell period was
identical in both for similar RPMs.  This jives with what I've been told by
various knowledgeable people on this list.  For example, Ludis said the Dwell
computations were identical in both .bins and apparently he was right.
 No explanations there for why the DIS doesn't work right with the 749.bin.

ALSO, I have a scanner which I hooked up to get data from the ECM.  It was
recording some very retarded (as opposed to advanced) ignition timing.  This
makes sense since the Reference Pulse from the DIS has a 50% duty cycle, as
opposed to much less with HEI.  Since the ECM reads the falling edge, the
falling edge from the DIS would come much later than the ECM would expect from
an HEI module.
I burned a new chip with the Main Spark table completely zeroed out.  With
this running in my car, the scanner read 21.7 degrees Retarded.  With a timing
light I measured the actual timing to be 12 degrees Advanced.  I tried the
same thing with the EST BYPASS disconnected and got identical results (as I
would expect with the spark table being all zeros anyway.)  So the ECM is
about 34 degrees off based on its interpretation of the Reference Pulse.
So I burned another chip and adjusted the Base Reference Angle 35 degrees.
Absolutely nothing changed.  This I cannot understand.  I burned another chip
at 90 degrees, just to see what would happen.  Nothing.  I tried some other
angles and nothing.  Apparently this part of the SyTy programmer is wrong?  I
don't know, but this is where I am stuck.
Also, even with the ECM reading 35 degrees off, the ACTUAL advance timing
according to the timing light is not that bad, so why does the car run like
crap?
I'm at a dead end, so tonight I'll sleep on it and hope I have some sort of
divine inspiration.  Or maybe one of you guys can think of something ;)

Ted