Delayed ref pulse (was Re: Spark latency correction)

[Ward]

You will find that the differnt Dist modules differ in the way they provide
advance in by pass. 

This is partialy because it works by increasing the threshold at which a
trigger is produced from the(sort of) sine wave reluctor signal. 

Also there are at least two versions of reluctors and module combo's for the
big cap HEI's, The input (reluctor signal is reversed. 

If you reverse the relutor wires you will get a about 45 deg fixed advance
and no variable function (in bypass)

Ward

On Mon, 20 Sep 1999 09:07:58 -0500, Don.F.Broadus at ucm.com wrote:

> This is an interesting thread lately I have been experimenting with the
EST
> spark using a Sun 404 distributor machine.
> I cut holes in the dist cap right under the #1 and #4 spark plug wire
> terminal using a hole saw. I connected the dist/coil/wires and
> plugs. The first test was in bypass mode, with a non inductive timing
light
> aimed at the #1 terminal the rotor was at the far end on the terminal
> indicating the 5 deg adv.  The rotor can actually be seen to move like
the
> old mechanical adv days.  I moved the RPM up from idle and at about 1200-
> 1500 engine RPM  the module acted like it snapped a switch closed and
> caused another 10 deg adv, As the RPM went up no further adv was noticed
,
> at 3500 engine RPM the spark is unsteady . I will bring out my notes
about
> connecting the EST to REF and post them. I have found all of your
comments
> very helpful  on this EST thread.
>  
> Thanks  Don      
> 
> 
> 
> 
> > -----Original Message-----
> > From:	Shannen Durphey [SMTP:shannen at grolen.com]
> > Sent:	Sunday, September 19, 1999 11:49 PM
> > To:	gmecm at efi332.eng.ohio-state.edu
> > Subject:	Delayed ref pulse (was Re: Spark latency correction)
> > 
> > Ward wrote:
> > > 
> > > On Sun, 19 Sep 1999 17:26:29 -0400, Shannen Durphey wrote:
> > > 
> > > > Ward wrote:
> > > >
> > > > > Please remember that spark advance is actuall dely, since yiu
cant
> > time
> > > > > travel backwards to start spark, its actualy delay from the prior
> > TDC
> > > event.
> > > > > to calulate a V8 time between TDC's do 15/RPM,
> > > >
> > > > I've tried to see this by routing the REF to EST and applying 5V to
> > > > bypass.  I thought that I'd see a displaced timing mark with my
timing
> > > > light, but it didn't happen.  What was I missing?
> > > > Shannen
> > > >
> > > 
> > > No. The delay in the processor won't be involved, and the inductive
> > > discharge is also not in that loop.
> > > 
> > > When you put by pass to +5 you switch the DRP output ckt from the
coil
> > > driver to the DRP pin. You also disble the startup dwell and timing
> > advance
> > > function. There is a 5 - 6 deg spark advance during by pass
operation.
> > > 
> > > So I don't see how that would show the CPU indiced delay correction?
> > > 
> > > Ward
> > > 
> > Sorry, I wasn't clear.  I'm not looking for delay correction.  I'm
> > trying to recreate a display which used a distributor, a 2 channel
> > scope, and a coil to show the delayed pulse that timing is calculated
> > from.  I don't remember an ecm in the display, but possibly there
> > was.  I don't have the scope and I was hoping I could use a timing
> > light.
> > 
> > The 89 Vette I was using showed no difference in timing, as viewed at
> > the balancer, whether the ecm was running on base timing or ref pulses
> > looped back to the EST terminal.  I expected to see retarded timing.
> > 
> > Shannen





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