EST Distributor

[sapearso at collins.rockwell.com]

I am going to second Shannen's idea about the factory service manuals. The
CHilton
is quite a bit better than the Haynes, but is still frequently misleading
at best.
As many of you know, I play with a couple of strange vehicles, and doing so
makes
the factory manuals really shine. Get on Ebay, there's a guy on there that
I've bought
a couple of factory manuals from. Pretty good prices too.

Scott


------------------------------

Date: Thu, 29 Mar 2001 21:06:06 -0500
From: Shannen Durphey <shannen at grolen.com>
Subject: Re: EST Distributor

Isn't this abbreviation in the FAQ?  It should be.

EST stands for Electronic Spark Timing.  This is a control mode.  The ECM
is in
control of spark timing (and dwell in distributor applications), with input
from
and output to the distributor.  The ecm also uses inputs from the other
engine
sensors to determine spark timing.  This is one of two basic spark modes,
the other
being Bypass mode.

I don't know what you mean by "the 8 eng coded 91".  The only distributor
which I
can think of with something close to EST, in addition to mechanical and
vacuum
advance units, is the 81 vintage 305 used in Chevy/GMC pickups.  This was
an ESC
system, which would retard spark when knock was detected.  I do not know of
any CCC
or later generation ecm/pcm controlled engine management systems which used
mechanical and vacuum advance in addition to ecm controlled timing.

You would be a wise man indeed to trade your Chilton's reference manual for
a real,
true GM service manual.  You should also consider finding the address for
the
company that supplies GM with its training materials, MSX.  The manual
titled "fuel
injection" will supply some very good reading material. Much of what you
are saying
is backward or misinterpreted, which could easily be attributed to a good
mind
learning from a poor source of information.

Shannen

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