Another Intro + DIS w/ '749 .bin

[Bruce Plecan]

-----Original Message-----
From: Tedscj at aol.com <Tedscj at aol.com>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Thursday, February 11, 1999 5:41 PM
Subject: Another Intro + DIS w/ '749 .bin


>big snip<
>Here's what I know (or think I know) so far:
>1: I read in a Chilton manual in the library that the signal the DIS module
>sends out is inverse to the signal an HEI module sends.

True

>2: I read in the archives that someone tried to run a .bin from a 6cyl DIS
on
>an engine with a distributor and it "just wouldn't run right"  They didn't
say
>it wouldn't run!  Just not "right."  However, I have never heard anyone say
>that an HEI based .bin (like the sy/ty .bin) wouldn't run on a car with
DIS.

List member has done it successfully using inverting technic..

>3: after reading the P4 document, I just learned that the P4 computer
controls
>dwell time.  I had always thought that was handled by the module.  I think
>this may be the source of the problem, Not the inverse signal.  The
document
>also states that the P4 reads the falling edge of the signal to determine
RPM.
>Even an inverse signal would still have the same number of falling edges at
>the same frequency, so I doubt that's the problem.  Though it may cause
things
>to be a few degrees off, but that could be fixed through the base reference
>angle.
>Could it be that the dwell computation for a DIS .bin would be to
aggressive
>to work well with a dizzy, whereas a dizzy based .bin (sy/ty) would work
with
>a DIS module albeit with rather conservative dwell times that don't take
full
>advantage of DIS?

The difference is the Dizzy has a timing per rpm correction, and the DIS
doesn't
the DIS systems use Hall Effect Switching, the Dizzies almost always are
reluctor/coil triggers..  The ignition module has a current limiter in it,
so it not really
a dwell contol devise other than by that feature.  As I've seen it the
timing tables
give you the total timing so the dwell, is "kinda a mute issue".

>I guess there is only one way to find out, and that is to try it!  Which
means
>I need to find a programmer that will work with a pentium based system (it
>seems that most won't) without causing me to go broke!  Any suggestions?

Think external, think finding old used laptop.  If you get serious long term
a
$100 laptop, and external will make sense.
Bruce
>Ted