EST Distributor

[Bob Wooten]

Len,

are you saying that the CCM is the "module" that the dealer was talking
about. & that it is another box between the Distributor & the ECM?

BW

-----Original Message-----
From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
Of Len Sabatine
Sent: Thursday, March 29, 2001 9:03 PM
To: gmecm at diy-efi.org
Subject: RE: EST Distributor


    Oops , * 8 th vin character IDs Engine . - 8 = 350 TPI.
    90 thru 92 F / Y Body = MAP sys, NOT MAF. 7730 ECM / F car , lives
    in pass compartment. 7727 [ sealed case] Y car , lives in engine
compartment.
    Both ECMs function same , use different  style harness to Ecm
connectors.
    You may have an early TPI Dissy. It is fastened with 4 hold Down
[Screws].
    A  common HEI cap won't work on TPI Hei Dissy.
    F cars don't use a CCM , they are used on Y cars.
    MisInformation is a bummer.
    Len

>I see.  I think that you are right, it is time that I get another source of
>information.  what I was using was the print in the manual & an educated
>guess @ how it works.  the description that Keith quoted makes perfect
sense
>to me now.
>
>the reference to the 8 engine code is to the VIN.  there were two TPI
engine
>codes in 91, one was 8 & the other F.  I think that the difference was one
>was MAF & one MAP.  the distributor diagrams in the manual that I have are
>different for them as well.  It appears that the 8 Engine code is the "HEI"
>style of distributor with the Coil in cap & the F is the tall thin
>distributor that I have that has an external coil.  but as I said, I don't
>have that one so I don't know what it really is.
>
>a fried of mine has an Iroc that is a MAF car.  His computer died & the GM
>dealer told him that there are two ECM's for his car.  one has the coil
>driver in the ECM & the other has another "module" that goes between the
ECM
>& the distributor.  this has always perplexed me as I don't recall having
>ever seen a GM "Module" that was not either in the distributor or in the
>ECM.  any thoughts or is this just another "parts guy" that doesn't know
his
>ECM from a hole in the ground?
>
>Tanx, again to all.
>BW
>
>-----Original Message-----
>From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
>Of Shannen Durphey
>Sent: Thursday, March 29, 2001 6:06 PM
>To: gmecm at diy-efi.org
>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
>
>Bob Wooten wrote:
> >
> > Questions #2, I think also another simple question.
> >
> > what is meant by EST?  I have a 91 Camaro that has an EST distributor
(so
> > says Mr. Chilton).  what I have noticed, & I am guessing but want to
clear
> > it up is that EST is more a scheme than anything.  this means that the
> > Distributor controls the spark duties w/the small input from the ECM for
> > retard & LHM.  this means that the distributor conditions the PU coil,
has
> > the driver in it for the HV coil & outputs a signal that is used to
> > determine RPM.
> >
> > another guess is that all the EST setups do not have any Vac or Mech
>advance
> > to them, but?????  I noticed that the 8 eng coded 91 has the "standard"
>HEI
> > setup & I think (I don't have it so....) that it does have both Mech &
Vac
> > advance on it still.
> >
> > thanks for clearing that up.  here comes #3.
> >
> > Bob Wooten
> > r71chevy at earthlink.net
> > www.r71camaro.homestead.com
> >
>
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