GM SmartCoils redux

garfield at pilgrimhouse.com garfield at pilgrimhouse.com
Wed Jun 24 22:59:03 GMT 1998


On Wed, 24 Jun 1998 15:58:19 -0500, Terry <thartman at gte.net> wrote:

>garfield at pilgrimhouse.com wrote:
>...snip...
>> and also that we've also
>> "reverse engineered" their DIS Ignition system, and are proposing to use
>> it as well on all kindsOcars, 
>...snip...
>
>Yep - this caught my eye.  Are you specifically referring to GMs 
>new DIS system in use on the LS1 motors?  (8 coils on the valvecovers)
>If so - I'd like to read any discertation you care to share.

Funny, I MEANT the older DIS system with the twin-tower coils and the
module base, but YEAH, we ARE also playing with the new "smart-coils". I
posted sumthin on them a while back. Go to the archives, do a TITLE
search using the keyword smartcoils, all run together jus like I typed
it thar. That'll get you the hit.

Normally, DIS is used to refer to the older system GM introduced where
the letters were s'posed to stand for "distributorless ignition system".
When you have per-plug IGN coils, that's usually refered to simple as
DI, for Direct Ignition. Not makin rules, just tellin what nomenclature
I've seen used to date.

On these new LS1 coils, they're directly driven by the PCM (new name for
ECM, now a "powertrain control module" cuz it tweaks with the tranny
too).

>Could the ICM (Ignition Control Module) & coil system be retro-fitted 
>to an older traditional style SBC without a crank trigger & cam position
>sensors?

I have nary a clue as to what an ICM is; never heard that before, unless
you mean just a "module". But these coils have all the electronics in
them to do the dwell compensation, etc., so they have NO module, but are
fired directly by a 5V logic level signal coming from the PCM. There is
NO separate system for just the IGN, the PCM controls all the IGN & EFI.

As far as a retrofit, not without some additional electronics. You need
at LEAST a crank wheel to fire these per-plug coils in pairs, and if you
really wanna fire only one plug at a time, then you HAVE to have a cam
reference as well. In addition to mere triggering, you'd need something
to model an advance curve, both the certifugal part that's rpm
dependent, and the vacuum part that's MAP dependent.

Rather than an older style dizzy based retrofit, I'd say these new GM
SmartCoils are more appropriate for someone who's gonna buy an
aftermarket ECU that's cabable of outputing spark trigger signals
directly, on a per-cyl basis. Then they'd be ideal, just one wire pair
from ECU to coil per cylinder, and poof coil/module DI system a done
deal.

Gar




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