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Wiring holley dominator efi

10K views 31 replies 7 participants last post by  HOOKERBEAR 
#1 ·
So I'm doing a dominator setup in my 1990 Mustang and I have been working on getting the loose wires on the main harness wired in. I wired the green wire to the tan/light green wire that goes under the hood and leads to the fuel pump relay under the drivers seat. I'm not 100% on where I want to mount the black wire, as I know it's supposed to have solid ground to both the battery and the engine. I took a look at where the negative cable on my battery led to and noticed it connected to the starter solenoid so I thought that may not be a good place to put it. If you have a good recommendation on where to connect that wire, it would be appreciated. I know the red and white wire needs to be a good 12v ignition source so I thought I could connect it to the red and light green wire that goes to the coil. The yellow wire I'd wire up to the negative on the coil. the red wire would be wired to the positive battery terminal (using a battery that has side and top post) on the battery side post along with the ecu power. The white wire won't be used because I'm using the factory coil/tfi ignition (since the factory coil is inductive instead of a capacitive discharge style system). Does all of this seem correct, all of the power sources are clean enough? No issues?

Another problem that I'm running into is, I removed the factory harness and the plug that goes onto the factory coil went with it and I sold the harness. Now I need to figure out how to wire the coil back up without the factory harness. How would I go about that? Go off the red and light green wire for power to the coil? Where would I wire the negative that connects to the coil? Does it just ground? If so, where does it ground to? Chassis? Engine?
 

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#2 ·
DO NOT GROUND ANYTHING TO THE STARTER SOLENOID! Only positive power at the starter solenoid.
Ground to the chassis or engine. Anywhere there is a good ground.

The EEC-IV grounds the relay to energize it and the Holley provides power so you'll need to ground the tan/light green wire at the relay and connect the red wire from the relay to Holley fuel pump wire.

If the EEC-IV main power relay is still in the car, the red wire you cut at the fuel pump relay will provide key on power for the Holley ECU.

The Holley TFI ignition harness (you did get the separate add on harness, right?) should have a white wire that connects to the negative side of the coil. Positive side gets key on power.
 
#6 ·
DO NOT GROUND ANYTHING TO THE STARTER SOLENOID! Only positive power at the starter solenoid.
Ground to the chassis or engine. Anywhere there is a good ground.

The EEC-IV grounds the relay to energize it and the Holley provides power so you'll need to ground the tan/light green wire at the relay and connect the red wire from the relay to Holley fuel pump wire.

If the EEC-IV main power relay is still in the car, the red wire you cut at the fuel pump relay will provide key on power for the Holley ECU.

The Holley TFI ignition harness (you did get the separate add on harness, right?) should have a white wire that connects to the negative side of the coil. Positive side gets key on power.
Yes, I got the separate harness.
So I won't use the yellow or white on the main harness. Ground black to battery, body, or engine.
I'm assuming my red is fine being hooked straight to the battery? Is it better to hook it to switched power?

Note: Battery has side and top posts. Positive side post powers ECU and red from the main harness is currently connected there, negative only has black from main power harness. Top posts are where everything else is connected, starter, cooling fan, ect.
 
#5 ·
I feel obligated to post a link to this thread that goes into all the details of a Holley installation in a Fox Mustang.

In addition, look for Note 2 in the above post, it's an absolutely genius way to use the OEM Ford ECU Power Relay to connect the 4 loose wires (red, red/white/black/green.)
 
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#15 ·
Turns out the Figure in the above post was incorrect and the split cable included the EEC wires and wires from the EEC to the EEC power relay (out->in), other power relay wires and fuel pump relay wires. I'm extremely pleased now as this is a simple exercise to wire things up now - I'll probably just run a new power wire for the fuel pump (yellow in pic) and same for always hot needed for Holley (red on HP). I can route these through the separate Holley power cable that connects directly to lugs on the side post part of my dual-post battery (tie them into a single or two ring-lugs.)

Anyway, I did have to lower the glove box (didn't need to remove it completely) to get to the EEC Power Relay. This was fun as a 1st project of the day as it was difficult to get my fat hand into the spot and a wrench. Turns out I had to use one of those tiny box wrenches that had a 9/32" on one end. I turned it like 35 1/4 turns until that stupid green fine threaded bolt came off. I was pleased that I had to put two band-aids on my left wrist as the lip of the dash edge slowly rubbed off my skin until it was oozing blood. :pain: Good thing I don't have a therapist, I might be put into the funny farm :lol:



I'm going to guess that most people wouldn't be extremely pleased looking at this mess, but I was ecstatic. There's so much add-on junk that I get to remove now - the list is long:

1. Add on loose wiring for Mass Air conversion.
2. Wires tapping into EEC for DataQ data acquisition
3. Wires feeding through for 2-step and shift light (I may keep these from my ignition box if it saves me I-O's on the HP)
4. EGR wiring tapped into for use as boost gauge (damnit, that's what those wires marked "1" "2" and "3" go to that I cut :( )
5. USB and switch cable for TwEECer.
6. Wires also tapped into for data acquisition through LM-1 wideband

I think that's all :lol:

 

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#16 ·
Whoa, it's been a while since I've heard anyone mention using a DataQ!
I have one of those for logging with a Moates Quarterhorse but never ended up needing it.
Did you end up getting your harness removed?

I have made exactly zero progress. Long work days do well to curtail my ambitions.
Hopefully tomorrow will bring at least a little progress.
 
#17 ·
I got the harness removed, labeled the connectors and individual wires so I can rewire efficiently as I can. I know these connectors don't align with a Mustang, though perhaps something I'm doing will help. I rerouted oil pressure gauge through the C317 connector so both ECT and oil pressure now jump from drivers side fender apron (through C312) directly to engine. The C315 takes -coil feed in for tach - so only one terminal needed on that connector. C294 has switched power (Red/Lt Grn) for +coil and Holley Red/White which I'll run through the Holley power cable sheathing.

 

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#22 ·
Ahh, sounds like you found a solution that works for you. I think I'm just gonna have my loose wires jump from the main harness to the Holley power cable which heads over to the battery. They can hitch a ride in there and I can steal terminals from the old harness and connect into the original plugs intended to bring those connections from the ignition switch/dash into the engine bay.

You would have had to splice into the wires on your connector since you don't have the mating connectors any longer, definitely cleaner keeping this under the dash in your case.
 
#23 ·
I used the factory wiring going to the old eec. I used a test light to find each source of power holley recommended. 12vdc, 12vdc key on, 12vdc key on while starting. I broke the connector so I replaced it with a weather pack connector. I suggest you buy a kit and crimper.

i bought the accu fab adapter and mopar IAC from freezy74. Works much better than the ford iac. You will need to change out the connector here as well. The oil pressure you can extend the wiring to it. Or I used a swage loc fitting an a 3/8'' piece of tubing to get the sensor up towards the valve cover.
 
#24 ·
Finally fired it up last night. Ran pretty good considering I overlooked that 5 & 6 plug wires cross over each other between looms - d'oh! :lol: I installed a shorty Holley cam/crank sync distributor (565-111) and had to transfer wires from old to new cap while #1 is also now 2 locations to the right from where it originally was (bosses on side of short disty prevented putting #1 in original location with Supervic.) Can't wait to run it today after work, will post up some pics of wiring - I love how clean it is with OEM harness completely removed.
 
#26 ·
I did. I had a bunch of the 150 series pins I bought for making connectors, so I used the pigtail that came with the oil sensor (cheap Ebay unit) and crimped male connectors onto wire ends. I heat shrunk each to protect them, then plugged 'em in and heat shrunk a piece over the 3 wires while plugged into the Holley connector to make a cheap and dirty "plug". Of course the cheapo sensor shows -3 psi pressure, so obviously it didn't care for being installed but not connected for a period of time.
 
#28 ·
I got all of my wiring done. I tried to fire it up today but only got backfire so I chose the wrong timing mark I made. I'll try to get that figured out tonight.

So as far as how I wired it.

The red with white stripe was wired underneath the steering wheel. I forget the colors of the wire but I probed and tested for power while cranking and while key is on. I ran another wire from that powered wire over to my coil to for spark. I then took the white wire from my TFI harness to the negative on the coil.

I now have spark and power to the injectors.

The black wire ground wire was ran to where the engine grounds to the body.

The solid red wire was ran to the positive on the battery.

The green wire to power the fuel pump was hooked to the solid red wire that was in one of the two plugs between the front DS shock tower. I then grounded the tan/light green wire from the relay to the body using the relay mounting screw.
I wired it this way to utilize the factory relay and inertia switch.

The white and yellow on the main harness was unused.

Power harness wiring was done simple, red to positive battery terminal, black to negative battery terminal.

I also took a little time to re-route my wideband sensor to the left turbo manifold, mount the sensor mounting block, ran a line from my FPR and oil sending unit to the sensor block and mounted the pressure transducers. Got everything plugged in, did the TPS autoset, and then onto the backfiring!
 

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#29 ·
It sounds like you wired it correctly. I was reading that the TFI type distributor should be set to normal 10 degrees advanced?
 
#31 ·
Holley recommends setting it there is what I was saying. Doesn't really matter what reference you use since the Holley unit controls timing from there afterwards, but the Holley expects it to be at 10 deg BTDC. I'm using the dual sync distributor which requires initial set up with crank at 50 deg BTDC.
 
#32 ·
Yeah.
I actually have a dual sync as well, I just don't have it installed yet. I just got it.

I got my car to start up but I have a massive vacuum leak to find. I managed to get it to idle but as soon as the throttle is touched it falls on its face.

Mine is the first dual sync they came out with that is complicated to set up. Should be an adventure setting it up.

I even managed to get my tach working. I soldiered from the negative on the coil to the tan and yellow wire between the DS shock tower and firewall.
 
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