[Diy_efi] Key-On Power for 7730

[Lee M. Lemoine]

I think i understand what your saying here, not being familiar with coils or
any of that sort of thing (Hey, i was born in '82 and fuel injection is
older than i am)...  That being said, i've never once tuned a carbeurator.

I believe your problem is that you don't have the correct setup on your
ignition.  You need a feed thats hot during cranking and in the 'on'
position.  I take it the ACC circuit shuts down while cranking also ?
(radio, wipers, etc)  That'd be my first guess.  If you can't get constant
power during cranking, a few things could be tried...

My thought on this instance, would be to utilizing a set of  zennier diodes
to power the ECM's "key on power leg"using the "IGN2" while cranking.
Simply using diodes, your essentially jumpering from the 'IGN2" position
back to your "IGN1" circuit, but preventing the IGN2 circuit from powering
anything up in the car other than the ECM.  I'd also toss in a large-ish
capacitor in line to 'fill in' that "gap" you speak of when the ignition
switch jumps the gaps as the key turns through different postiions.  This
way a new branch off of your IGN1 circuit is hot in both the start and run
positions.

If you need a schematic or further explanation, let me know i can draw out a
schematic.  It shouldn't cost too much as the ECM doesn't pull too much
current during cranking -- the diodes will be the largest cost, with the
capacitor being secondary.   It's a simple wiring job and can be done at any
convenient point in the wiring harness (so you don't have to picture taking
your column switch apart to accomplish this!)



On 9/27/06, Clair Davis <clair.davis at charter.net> wrote:
>
> Background... I've got a 69 Plymouth Valiant I'm multipoint-injecting with
> a
> 7730 box.  I've got two wires left to run, and one of them is killin' me:
> Key On Power.
>
> On my old Plymouth, the ignition switch has 5 wires: BATT, START, ACC,
> IGN-1, and IGN-2.  IGN-1 is the "run" power to the coil, dropped down with
> a
> ballast resistor to keep the coil happy.  IGN-2 is 12V straight to the
> coil
> for hotter sparks while cranking.
>
> The IGN-1 circuit is DEFINITELY dead while cranking, and IGN-2 is ONLY hot
> while cranking.  Once the engine fires, you let up on the key, the switch
> rolls back to IGN-1 and you go on about your way.  Problem is, I can't
> tell
> how long the dead skip is in the transition between the two circuits.
>
> Is this a problem?  Seems like it might be, as the "key on" signal seems
> to
> be the trigger for the whole start-up routine with the ECM.  Is a GM
> ignition switch one where there is no break in the power from "run" to
> "start" and back, or am I overthinking things?  Mopar guys that run MSD
> ignitions splice IGN-1 and IGN-2 together for the MSD to work, but that's
> hardly the same animal.
>
> Thanks in advance!
>
> Clair
>
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-- 
Sincerely,
Lee M. Lemoine
KB1NQI  - Amateur Radio
http://www.turbochargedsoul.com/
'06 Subaru Legacy GT Limited - 250/250 AWD 5EAT
'93 Chevy Cavalier Z24 Convertible - 300/330 FWD 5MT (Mclaren Turbo!)