[Diy_efi] Re: CNP source

[J. Creech]

> I am doing a twin-plug conversion to my 911 Turbo.  Any good sources of
> the latest GM CNP's, as above? Part number?  NAPA?  Thanks.
>
>
>
> Marc J. Reviel

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I've saved a few emails from this and other lists over the last few years, this is what I
could find about the GM latemodel CNP setups. I *thought* I had one saved with a current
part # - but can't seem to find it in the irrational pile of effluvient I call "My
Folders".

-Scott C.
-------------------------------------------

This is cut from an email by Jurgen Hartwig:

Regarding the CNP, or rather Smartcoil, as it was called in 1998 archives,
here are two pieces you and others might find interesting.  Both below
quotes were written by Gar, I believe of EGOR fame.

"A guy in our Aviation group that
works in a GM lab sent me one of these off a decommissioned test
vehicle, and they are NOT mere IGN coils, they're complete single-coil
IGN "systems". They contain ALL the electronics for dwell control,
current limiting, etc etc. These coils are DIRECTLY run from the
ECM/PCM. There is NO module. They have 4 terminals (plus the HV
terminal, that uses these ratchet style terminals I was tellin bout
yesterday), two for Bat Gnd, and Bat +12V, and the other two are the
digital EST signal and it's low-noise gnd return. Not usable for ION as
a transformer-type coil, cuz you cain't get to either the primary or
secondary on these puppies, but still a VERY elegant setup, indeed.
That ain't all. The biggest shock is yet to come. Brace yerself. They're
actually CHEAP (and nice and light, too). I couldn't believe it when I
went to check them out further. The GM parts counter LIST price is $41
for each "smart coil", and EVEN the harness for tying four of them
together is reasonable, list price of $62. You get 4 connectors for the
4 coils, and another larger connector. Not a bad price for 4 GM
connectors and pigtails (if you decided you couldn't use the harness as
is), at the very least, and you might even be able to get the bigger
connector from Packard! The shorty coil wires (yes, these DON'T squat
ontop the coils) have them real nice connectors I mentioned, and they as
well are pretty reasonable, at $11 ea list."

And

"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."

Bob, I know these "Smartcoils" are available on the V8 Camaros.  You might
be able to find these in a wrecking yard.  You can also wire the two
triggers together, ala DIS.

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

> That is correct.  Wolf dealers actually use them, and I can purchase them
> for about $50-70 a pair.  This is my most cost effective route, and I'll
> probably do it, since I know it has been done.  I saw the posts about the
> "smartcoils" and thought this would be worth investigating.  If I read the
> post correctly, Gar mentioned that you might/could use the single coils in
> waste spark fashion by tying the triggers together???

Yes, still one coil per cylinder though.

I've run my car on these coils using a PIC based circuit to
distribute the ignition signal to the individual coils.

Driving them is easy - raise the trigger signal over 2.7V then
when you are ready to fire, ground the signal.   You have to
be careful when you 'arm' them since they will fire after
1/10 second if you leave the trigger signal high that long.

-Orin.

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

Andrew Theurer wrote:
>
> I'd look into the LS1.  I think they have the ignitor built into the coil
> itself.  The jobber price may be around $35 each.

Yes, they are probably your best bet for a retrofit.  The true COP (LS1 coils are
"coil near plug", i.e., they have a short wire) requires that you somehow support
the coil appropriately out at the end of the plug, so the you'll need some weird
bracketry.  The CNP allows you to bolt the coil to the head or the top of the valve
cover or whatever is convenient.

-Eric Fahlgren

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

At 02:42 AM 3/7/01 -0500, you wrote:
> >Bob, sorry I don't have the info about the pin identification.
> > Hopefully, someone can assist.

My 2000 Camaro shop manual shows the coil connections are:

A - Ground
B - Reference low  (seems to be ground in the PCM, probably ground return
for the "Control signal")
C - Control signal
D - 12V with ignition on.

The manual indicates that the coil is fired by grounding pin C.

I hope that helps.

-Ira Emus


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