Holley EFI Ignition Wiring

[2059]

Gonna post this question here because searches turned up nothing here or the other forums. Pretty narrow question, but lets see who's out there. finishing the tie up on the electrical side if the Ignition Circuit for the ECU on a Holley Dominator EFI with an Aeromotive Fuel Pump Controller. If I connect the ignition hot to the to the run side of the switch, I get nothing at crank and visa versa. any suggestions on where to tie in to get hot in both conditions. I'm trying to avoid a panel of switches. BTW, cant run a jumper between the two at the switch, will fry the coil.

'64 dodge with a stock electronic ignition conversion.

 

[Meep-Meep]

It sounds to me you just duplicate the factory setup. The crank mode bypasses the ballast and puts 12V to the coil but only in crank position. Then once you let go and the switch snaps back to the run position you get the voltage drop through the ballast. Ignoring all that you can suck 12V from the starter relay control circuit to satisfy your crank voltage requirement and not have to go through the bulkhead.

 

[beezee]

On my 68 Bee I used the brake warning light feed wire as 12 v from both start and run on the keyed switch.

 

[dpstark2]

This is a common problem with these cars and adding EFI. I'm not sure about the brake light feed, but that would be an interesting option if it works on most or all cars. For my EFI conversion, I was able to eliminate the ballast resistor. Tying both factory terminals together there creates a circuit that is hot in crank and run. I use this to a control a relay that switches most of the other high current circuits, and I source low current stuff directly from the new joint crank/run hot circuit. This does not affect the starter relay control wire, which seems to be on its own feed through the ignition switch. Also, I don't know if the wiring changed drammaticaly between '64 and '67, but I believe this is the same system from '66 to '70.

If you can't eliminate your ballast resistor and the brake warning light feed doesn't work, you'll probably want to look into using two relays in parallel. You can grab one "start" line and one "crank" line (both sides of the ballast resistor) and feed them to the control side of two separate relays. Then tie the relay outputs together and feed both relays through a fuse to the battery. You may also be able to find a dual-control relay, but I can't think of one off the top of my head.

 

[440roadrunner]

Let me understand? You are running what, Mopar electronic ignition?

And you are talking about what, the red / white Holley "trigger" wire?

A few ways to do this.

One would be to replace the start relay with the later Jeep style, which has an extra contact:

like this one

http://oljeep.com/gw/elec/StarterRelay.jpg

Same idea would be to add a Bosch relay, triggered by the start wire now triggering the existing start relay

Either of the above, you you feed the load contact off to parallel your ign run wire

Yet another and probably simpler way would be to use a couple of rectifier diodes as "steering" diodes.

Come off your ignition run and feed that to the Holley through one diode

Come off your "start" or "bypass" terminal and feed that to the holley through the second diode.

===========================

What this will do is keep the Holley powered in "start" but will NOT allow the bypass circuit to hold the ignition circuit on. You notice that "factory," various things in the car go dead in "crank." That is the cause of the "ign run" circuit, and if you hold that "on" in crank it will cause an additional load during start.

===================

Like this

The "load" represents your Holley trigger wire.

The left top diode connection can be the "ign run"

The left bottom diode connection can be the "bypass" or "start" terminal

 

[Yatzee]

440's spot on. Don't eliminate the diodes or you'll get "back feed". Relays are a must so you're only controlling the coil of the relay not the main power feeds. GM relays have the diode incorporated right in them as does other aftermarket brands but you need to specify that or buy them separately.

 

[dpstark2]

I have to slightly disagree with the diode approach. I know it's common to do so, but to find a diode that will handle underhood temps and be reliable, you're going to lose ~.5V across the diode if you draw several amps through it. Assume you're losing that .5V and drawing 10A. That's 5W. (I know this is unrealistic, I'm just trying to make a point). You now have a 5W heat source trying to dissipate that from a small package.

Yes, it can work, but it isn't the best method in my opinion. If you want to use diodes, go ahead and do so but wire them to the control side of a relay and switch a 12V source with the relay and power everything off that relay. You also really don't want that voltage drop going to anything that's going to suck down any significant power, especially anything EFI-related.

Just my opinion- I don't want to lose voltage anywhere I don't have to.

 

[2059]

Thanks for all the input guys. Yesterday I had a little time to trouble shoot. Pulled the pump controller ignition hot off the key switch circuits completely and fed power off the aux fuse block through a toggle switch. Flipped the switch, the pump primed and the second, as it should, I turned the key to crank and the controller kicked out the pump and flashed a fault. I thought OK; I'll disconnect the tach signal wire and use the override for full pump speed all the time. Still running main power through the pump controller, the second I hit the crank position with the ign. switch, same result. I won't have any time until Saturday to work on this but at that point I'm going to remove the controller completely and run feed through a standard relay off a toggle switch.

Aeromotive P/N 16306 if anybody wants to see the controller.

 

[2059]

After finishing the above mentioned changes, the pump operates fine. Discovered I had ZERO spark. Basically secondary system was not firing. Long story short; called Holley Tech. this HP EFI will not recognize Chrysler's electronic box. I need to go with an MSD Box and Coil. I'll probably buy the Distributor too while I'm at it.

Tune in next week for another episode....

 

[440roadrunner]

I have to slightly disagree with the diode approach. I know it's common to do so, but to find a diode that will handle underhood temps and be reliable, you're going to lose ~.5V across the diode if you draw several amps through it. .

First, you don't HAVE to put the diodes under the hood, but even if you do, many modern cars have underhood diodes for various reasons. However, there is no serious load on these. The Holley "IGN" wire is similar to the MSD "trigger" (small red) wire. All it does is to "enable" the box. main power for the ECU is dedicated hot and ground through two larger wires.......just like MSD