A most excellent post! :-) I knew the 'puters controlled everything and
therefore thought the distributor was kinda useless in a modern engine but I
wasn't sure until now... I guess it wasn't cost effective for D/C to fab up a
coil-on-plug setup for the 318 or 360? I, for one, would not have minded
seeing a distributor-less 318 on my '98.
Tom
______________________________ Reply Separator _________________________________
Subject: DML: Re: Magnum ignition systems - how do they work?
Author: <dakota-truck@buffnet.net> at smtpout
Date: 2/10/00 10:51 AM
I would have to agree with V8dakLECC@aol.com on this one - the crank
sensor is the only thing that is required to provide ALL ignition timing
to the magnum motors (V6 & all V8s). The PCM simply switches the ground
circuit on and off inducing current in the high-voltage windings of the
coil. The timing of which is completely controlled by the PCM
(requiring a new program to change ANYTHING). It can do this due to the
resolution that the crank sensor provides - down to a few degrees of
crankshaft rotation. For example suppose the computer is providing X
degrees of timing at 2500rpm. If it decides to advance the timing 5
degrees at 2500rpm - it simply toggles the ground circuit at X-5
degrees. If it decides to retard the timing 5 degrees at 2500rpm - it
simply toggles the ground circuit at X+5 degrees. All in the computer
baby! The distributor does just that - distributes the spark to the
correct cylinder. This is why moving the distributor can have very
detrimental effects - surely you dont want to change the firing order!
This potential mechanical 'error' as well as wasted spark energy are
reasons why the distributor (obsoleted) has been replaced entirely using
direct-fire coil-on-plug setups like on most production vehicles today.
Questions? Send em - I try my best...
Latr,
Shane
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