747 Timing Connector and misc questions

[Jason Weir]

Bruce Plecan wrote:


> No, no, no
> The ESC is for retarding the timing due to knock.   It sends a signal
> to the ecm when knock is detected.  The ecm then retards the timing.
> the ESC is the thin black box about 2"x2".  All it does is listen to
> the knock sensor.  When it hears the right noise it tells the ecm hey
> we got knock.  Trouble with this system is that certain sounds sound
> like knock, and can falsely trigger it.
>
> With the timing connector disconnected (tan/blk wire) the ecm has
> no control over the timing.  The only timing is what is inherit with
> the actual design of the electronics.

inherit in what electronics, ECM, ESC? That doesn't make sense to me, If
you look at the graphs I posted

http://home.att.net/~jweir/graph.html

the curves follow each other really close. if what you say is true that
with the bypass disconnected the ECM had no control over the timing
curve then why do they follow each other so closely? coincidence?

> When you rev a ecm timing controlled car in neutral (gm ie 747) the
> timing curve you see with a timing light has nothing to do with what
> you have in gear, or when driving the car.  The timing curves you
> have posted have notthing to do when the car is in gear, or when
> a vss is present.

I have VSS disabled, so that doesn't play a part in this equation, in
the timing table the timing curve is based on RPM? I understand that
there is a WOT spark add, is there also a TPS transition spark add as
well, and maybe a MAP spark add (vacuum advance)?

thanks for giving us ignorant folks a helping hand, Jason Weir
--
Jason Weir - 88 YJ - 258 / Howell TBI  145K and counting
Fayetteville, North Carolina
JTW Web pages at http://home.att.net/~jweir
mailto:jweir at worldnet.att.net