All of these questions (and more) are answered in the HEI upgrade instructions. At least they should be. If you find one not answered there, please let me know and I'll write it in.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan, Here is the first new dumb question. Well,maybe. I have read all the links, and all the diagrams in this thread, and so far I have seen diagrams that show how to hook the HEI module up to the two wires that come from the Mopar distributor, and from there onto the coil. This seems very straightforward and easy to understand. It is almost a no brainer, although I imagine I would find a way to foul it up.

What I have yet to find is a diagram for how to wire up an HEI module if you are trying to fire it with a single trigger wire from an ECU. I am guessing it can be done, but so far I don;t know how. Anything I do electronically has to come from just pure faith in what someone else says will work. I don;t have the knowledge to figure out the logic of electronic devices. Basic electrical circuits I can kind of grasp, but electronics are a more complex issue, because mysterious, magical things happen inside the little black boxes filled with diodes, and transistors, resisters,etc. It's like Slim Pickens goes in one side, and comes out Jessica Alba on the other.

I looked at the Bosch units available, but they are all plug and play OEM units with specific applications, and again, I would not know how to wire them into my set up. And again, Accel does not help much with their lack of real diagrams. Thanks for the willingness to help so far. Think of what a great challenge I am to your greast teaching ability and patience.

Sam

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I am pretty sure this will be a simple matter. Unless I'm on glue, the two wires coming from the distributor pickup are signal and ground. So, your one wire from the ECU should be "signal", and you'd make the missing second wire by tying into the ground loop that grounds all your other sensors (or just by making a good-quality ground). Then you'd proceed per the articles — that is, connect the trigger and (new) ground to the module, hook everything else up, make sure the module itself is well grounded and heat-sunk(?), and attempt to start the car. If you get hard starting and rough running, swap the trigger and ground wires' positions on the module and try again. If it starts and runs with either hookup polarity, pick the one that gives the best starting and running.

Oh, and don't forget, you really need a better-than-OE coil to make this work out well...
They work on the FM principle ("Magic").

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

We only sell the core to an ignition module at the moment. We managed to buy up a case of Bosch BIP373 power transistors, which are the actual driver inside some of Bosch's ECUs and ignition modules.

For a complete module, if you can get a 0 to 5 volt signal out of the Accel box, I'd try a Bosch 0 227 100 124 or equivalent. The MegaManual has a wiring diagram for them here:

http://www.megamanual.com/ms2/Bosch_124.htm

With a DFI system, it looks like you'd wire it the same way except the purple wire would go to whatever connects to the MSD box's white wire now.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

At the risk of belabouring my opinion, I have never thought very highly of Bosch's electronic ignitions.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've seen 4 pin HEI modules wired the way Dan describes, and yes, it does work. The HEI module incorporates dwell control, unlike the Bosch units.
Belabour away if you like, I'm all ears. I've been planning an ignition shoot-out once I get the Dart running, to see how a HEI ignition, an MSD-6 box, and several other systems compare to each other.

The Bosch transistors seem more heat resistant and harder to kill with too much dwell than the previous thing used in the Megasquirt world, ON Semiconductor's VB921VZFI. Then again, the main reason for adapting the VB921 was that overdwelling it wouldn't fry traces on the main circuit board.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

This gets more interesting. I think I finally understand how to wire the standard 4 pin HEI with the setup I have. And, I can do this. BUT:

What are the implications of the module being "smart" or not? Will the HEI module's control of dwell fight with the Accel ECU? I was told by the speed shop here which installs Accel EFI that I did not want a module with dwell control built in. This is something I know nothing about, and cannot have an opinion about with my current (no puns intended) limited understandings. Do you think the ACcel ECU controls dwell? Does MS control dwell, or does it look for this feature in its control module? How does dwell effect what the ECU sees? Am I in danger of burning something out in the ECU with the HEI's dwell control. Your comments, Matt suggest that this is a concern with MS. Accel does make a harness for EFI interface, so you would think it is OK tio use a an HEI module. But maybe not all HEI modules are "smart". Maybe the numbers listed in Dan's post have no dwell control built in. What can you say about that?

If the Accel ECU does not want a module with dwell control fighting with it, or interfering with its dwell control logic, then maybe the Bosh 124 is the way to go. I hope this doesn't feel like beating a dead horse to you guys, because it is new and interesting territory for me. Thanks for your patience.

Thanks Dan, for your further clarifications for on wiring the HEI with the single signal wire from the ECU..

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We are moving further afield from my firsthand knowledge, but I cannot imagine the Accel ECU being able to know — or caring, even if it could — via its single signal wire, that the 4-pin HEI module controls dwell (i.e., coil saturation duration).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Mostly that you need to set the ECU's spark output to match the signal the module is expecting.

With a "dumb" module, you need to specify the dwell time in the ECU, and running too much dwell time can damage the coils. Smart modules control dwell but often need to be paired with specific coils.
The guy at the speed shop isn't helping; your MSD box itself falls into the "smart" module category. If you try to control dwell with the ECU and also use a module that controls the dwell, the module will normally override the ECU's command. According to Accel's website, it can be used with both smart and dumb modules. Here's a list of the modules they specifically state it can work with for a Gen Seven - I think there's a few on this list that earlier ones don't always work with, but it gives you an idea.

DFI Dual Sync: Unknown.
GM High Energy Ignition: I believe they're referencing the 7 or 8 pin varients. On these, the module controls dwell during cranking and the ECU controlls dwell during normal operation.
GM LS1 coil on plug: ECU controls dwell.
Ford TFI: This one exists in both computer controlled dwell and module controlled dwell versions.
Ford EDIS: A rather weird one, but ultimately the module controls dwell. The ECU's "dwell" settings control the timing.
MSD: There isn't any dwell here, but it's closer to a smart module than a dumb module.
Both of them are capable of dwell control, but it is possible to disable this feature in either one.
It doesn't, as it only affects the output.
Not really, the only danger is hooking a coil or other high current device straight to the ECU.
Only when the MS is firing a coil directly.
All known 4 pin HEI modules control dwell, since the magnetic trigger they read from can't control it.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Again, thanks for your patience with my need for very basic education here. And thanks for pointing me in the right direction. I am really out on the skinny branches now, but I think I need to keep asking questions to get this EFI really under my belt so to speak. And I think this interface between distributor, ECU and ignition has been the weakest part of my understanding right fromt he start. It was the source of my initial start up problems, and the area that I could not seem to get help from Accel or Rance early on. The lack of real diagrams, but only black-box harness connection diagrams made it impossible for me to interpret anything meaningful in the wiring diagrams.

There is a chart in the Accel manaul that discusses "something" rising, and falling, and various combinations for this kind of event. I thought they were talking about the pick up signal going to the ECU. However, reading here suggests maybe they are talking about the kind of output from the ECU the ignition module needs to see. I will read the manual soon and see if this begins to make more sense to me. There is a calibration menue in the tuning program that lets you chose various configurations in this regard. Am I anywhere near to something boardering on a correct understanding here? Again, my knowledge is very, very sketchy here. I may be slow, but at least I'm not fast.

Sam

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