[Diy_efi] 2.0 diss module with the 1227749

[Shannen Durphey]

Djfreggens at aol.com wrote:
> 
> ahh the schemtic i saw for the dis module showed it to only use the same
> wiring as the 1227749 module with a crank input.so heres my thoughts
The dis module does have some additional outputs, but the 4 basic wires
seem to function the same from DIS to dizzy.

> 
>   need to change the ref angle in the 749 code to 60 btdc
>   and install the correct crank reluctor and sensor. sound about right to you
> this would be the simpilest apporch.
Would be if it worked.  For one thing, the hex value that should be
equivalent to 60 deg is not going to give the correct offset.  I dunno
what's up, but it doesn't.  Then there's the fact that the values labelled
"max advance" and "max retard" in most tuners I've seen are misleading.  I
spent a fair amount of time trying to understand exactly how gm code
delivers the correct value to the coil control hardware to understand why
this is so.  This isn't one of the situations where a guy can say "Oh,
that's just the spark section of the code" and leave it.  The short version
is that "max advance" would be more accurate if it were called "maximum
positive timing value," and that you need to understand whether your
reference point is positive or negative before you can relate a positive
(or negative) timing value to advance or retard. And once you get to where
the spark looks like it's being delivered correctly, there's other non
trivial stuff involved in making a correctly working calibration.  I don't
have a final answer, but I have a _large_ folder full of notes and
observations made while trying to get this combination to work.  I'm
nowhere near satisfied that it's ready for primetime yet.  If you ask for a
definite answer, I don't have one. 

> 
>   btw this is for my 1986 honda accord. the stock dizzy uses mechanical and
> vacum adance so i figure tossing it will make life a whole lot easier. not to
> mention the coolness factor of DIS ignition.

Not to dis the DIS idea, but it'd prolly be faster to get it up n running
to find a way to use a honda dizzy as a trigger for a gm ignition module. 
It'll be cool when it's done, whichever method you use to deliver spark.

Shannen

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