DIY_EFI Digest V1 #277

[talltom]

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>From: "Robert J. Harris" <bob at bobthecomputerguy.com>
>Date: Tue, 17 Sep 1996 10:25:23 -0700
>Subject: Timing - Ignition
>
>Subject: Ignition timing in conjunction with EFI
>
>There appears to exist a number of sensors to build
>an excellent self tuning EFI, yet the only sensor that
>anyone talks about for ignition timing is a knock 
>sensor that just tells me - oops too much - 
>self destruct sequence initiated.

Not me! I'm full of it! But I'll definetly have to agree with your synopsis
so far!

>Factory curves and random published curves are all
>that most without dynes have to work with.  Back in 
>the bad old days, (pre computer) the killer secret for
>street tuning was to advance the static initial timing
>watching rpm and vacuum, until you got the max 
>you could get and still start the engine, then put a
>sping kit in adjust the mechanical until the total was
>the same as what ever your guru of choice had
>dicated.  Look for ping or knock, then put some
>more in.  It works but had too much PFM (Pure F___ng
>Majic) to be reliable for all engines.   Since then, many
>bandaid seem to have appeared.

Hear here! The BS never stops!

>Since we now have computers, we should be able to
>monitor something other than self destruct imminent and
>tweak and peak the timing in conjunction with the fuel
>to get optimum power and economy.

YEAH!

>I truly hope that there are some good ideas out there.
>

All kinds of stuff! 84 Datsun z cars had a factory g-meter on board, although
limited to .5 g's.(A good hard launch at the strip is at least 3g's.)
It may be that the current gear may be needed to be taken into account, but I
don't see it as mandatory. Vacuum is still a viable indicator, although one 
needs to consider that an efficient engine will be throttle per cyl. Another 
thing to keep in mind is system speed. To fast will read pulsations in vacuum,
to slow will adjust timing after destruction, at which point it's immaterial.
   It would also seem to me that the thing should have a learn mode that would 
be able to tune for varying load.(In my case from 7000lb-17000lb, without
trailer)
   I have to think that there is already out there somewhere some dyno loading/
running software that could be used to avoid reinventing the wheel.
My inclination would be to set up a graph of rpm/vacuum and have the processor
wiggle the timing and pulse width within a percentage to achieve best
acceleration.
It may even be possible to setup the jigling parameters so that they are done as
a subroutine that is specifiable for a vacuum or rpm range.(Hope ya'll excuse
the 1977 basic terminology:-)
   
>Remember the Reichstag

I do, and see the same mo happening frequently today.

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