Nomad final assembly

[chevynut]

Yesterday I got the 10-pin connector on the distributor changed to a 4-pin one. Then I turned the engine over by hand to 50 degrees BTDC on #1 so the old distributor is ready to remove and drop the new one in. I ran the fuel pump with the fuel rail still off and flushed the supply line up to the fuel rail/regulator.

Then I removed the entire C950 harness and labeled the wires that need to be re-connected to the TerminatorX harness. i salvaged several of the connectors off of it since the harness is basically trash now.

IMG_6736.jpeg


I plugged the new harness in and separated the wires into two bundles, one bundle that goes to the engine compartment and the other that does not. There's WAAAAAY too much wire in a 15 foot harness....8 or 10 feet would be plenty. I've made several schematics showing how everything needs to be wired up.

Next step is to mount the CDI box and run power and ground to it and the ECU. I think I want to remove a couple of wires from the CDI box harness too, since they're for a magnetic pickup which I won't be using. Then I need to start connecting the new harness wires inside the car and run the rest of them through the firewall.

[chevynut]

Still working on the Nomad as much as I can. I got the CDI box mounted where the C950 ECU was. They want you to put it on rubber vibration isolators, which I did, but I'm not sure they even do anything. I did remove the two magnetic pickup wires from the CDI box, and I also removed 5 more input/output wires from the TerminatorX connectors. I just can't think of anything else to do with those I/Os. I am using one input and two outputs, same as the C950.

Today I removed the old 4.2 O2 sensor and installed the new 4.9 one. It was a bit of work getting it routed into the console, but I got it done. I also installed the new fuel pressure regulator in the fuel rail, and temporarily installed the harness/fuel rail without the injectors so I can wire up the connector to the main harness.

Now I'm ready to start cutting and crimping terminals onto the wires. It should be pretty easy until I get to the engine compartment. I'm trying to document everything and go slow so I don't make a mistake that would be hard to find.

IMG_6739.jpeg

[chevynut]

Turns out Holley says to wire power and ground for the TerminatorX ECU and the MSD CDI box directly to the battery. As long as you have good connections and proper size wires, you don't need to go to the battery imo. I have a 1 gauge wire from the battery to the starter. Then I have another 2 gauge wire from the starter to a large fuse box in the console. An 8 gauge wire feeds all 5 breakers mounted in the console from there. I plan to run a 10 gauge wire from there to a 30A breaker, then to the TerminatorX ECU. I plan to connect the ground wire to my rear seat frame mounting bolt that goes into the body. The rear seat frame is aluminum and is grounded in several places with bolts. I feel this is better than running two 10 gauge wires all the way to the battery. Plus I have been told that the ECU only draws around 10A so I don't understand the need for the huge wires.

As for the CDI box, it uses 12 gauge power and ground wires. It only draws about 6 amps at full power, so again the wires are overkill. I plan to run the constant power to a 10A fuse in my fuse panel, then the ground to the console base. The console base is grounded in numerous locations to the body, which is grounded to the frame and battery. Again, this is better than running 12 gauge wires all the way to the battery imo.

[chevynut]

I've been plugging away on the wiring as much as I can. Got power and ground wires run to the ECU and CDI box. I removed three wires from the CDI box and ran the "points out" wire from the ECU into one of those locations. The other two are unused in my application. I've re-wired the fuel pump relay and the 3 I/Os that I'm using.

All I have left inside the car is installing the O2 sensor connector. They give you no sensor pinouts for the 4.9 sensor, and Holley sells an "adapter harness" for it and the wiring diagram for it is not available, at least I can't find it. So I searched and found some sources for the correct 4.9 sensor wiring and signals, and mapped them to the ECU harness. Once I get that connector installed it's on to the other side of the firewall.

The left side of the console in this picture is all the new ECU wiring. Lots of stuff to keep straight.

IMG_6749.jpeg

[WagonCrazy]

Looks good Laszlo. I like your description of your +battery and -ground wire rationale. It seems logical to me, and is how I wired mine up too (lots of grounding points all tied into to the chassis/block and a few common +battery connection points near where power is needed...rather than multiple long runs back to the battery itself).

[chevynut]

I thought I finished the interior wiring a couple days ago. However, I just realized I forgot to put the braided shielding on the coil wires like I wanted to do to prevent EMI issues so I'll probably have to backtrack a little. Damn.

Everything has power and ground and all the interior signals like the tach, FP relay, I/Os and WB02 wiring are done. The WB02 connector was difficult and contacts are small, and in retrospect I should have cut more of the sheath off of the cable to free up more of the wire length to work with. I also put the red protective covers on all the breakers so nothing can short out on the studs.

IMG_6753.jpeg


I've started on the engine compartment and have cut the wires down to rough length but I have to get the shielding on the coil wires before I can finish them. I split the sensor power into two leads, and the sensor ground into four leads. The injector harness connector is installed. I plan to use black braided wire loom so you can't see the wiring and I need to put it on the coil wires and other wire groups so I can put the connectors on the main engine harness. I'm working on the injector connector, then the distributor, coil, and on to the 4 EFI sensors and IAC.

[chevynut]

I like your description of your +battery and -ground wire rationale. It seems logical to me, and is how I wired mine up too (lots of grounding points all tied into to the chassis/block and a few common +battery connection points near where power is needed...rather than multiple long runs back to the battery itself).

I don't understand why Holley is so adamant that you have to connect power and ground leads to the battery. They claim the battery acts like a "filter". So you have a battery with two long 10 gauge leads to it from the ECU. I fail to see how that's better than a short 10 gauge wire, a short length of 8 gauge wire, a couple feet of 2 gauge wire, and a long 1 gauge wire to the battery. And as for ground, I have about 8" of 10 gauge wire, then the car body as a ground conductor. They even say not to connect it to the starter lug. I have seen no rational explanation as to why they think connecting directly to the battery is necessary. I think they're just trying to CYA for guys who don't know what they're doing.

[BamaNomad]

The battery can be viewed as a giant capacitor, which smooothes out spikes caused by such things as alternators, starters, etc..

If you have an oscilloscope, hook it up to the battery (and alternatively) to wherever you are planning to power your Holley device, and view power spikes at each location during alternator charging, engine running, starter engaging, etc...?? I suspect they are just saying hook it up as 'close' to the battery itself as possible and farther away (electronically) from the spike generators. The battery FILTERS out spikes on your DC circuits wherever they are hooked up but it may be better filtered when connected closer to the battery?

[chevynut]

[QUOTE=BamaNomad;68129]The battery can be viewed as a giant capacitor, which smooothes out spikes caused by such things as alternators, starters, etc..[/quote}

I agree, but why does it matter if you have 10 feet of #10 wire to the battery or shorter lengths of larger wire? It still goes back to the battery.

If you have an oscilloscope, hook it up to the battery (and alternatively) to wherever you are planning to power your Holley device, and view power spikes at each location during alternator charging, engine running, starter engaging, etc...?? I suspect they are just saying hook it up as 'close' to the battery itself as possible and farther away (electronically) from the spike generators. The battery FILTERS out spikes on your DC circuits wherever they are hooked up but it may be better filtered when connected closer to the battery?

I don't have an oscilloscope, but I understand electricity and electronics. What you need to do is minimize the total resistance to the battery which is what matters. I'll bet the resistance of my connections is lower than long #10 wires. With low resistance, a capacitor acts the same no matter where it is in the circuit. The voltage at the battery is going to drop virtually the same as it will at the starter when cranking.

Here's what Holley says "Holley HP and Dominator ECU’s use the same main power cable. These wires should be run directly to the battery. 10 gauge wire is used. The harness comes with a 40 Amp fuse pre-installed. Do not substitute smaller gauge wires."

The 40A fuse is also unnecessary, as I was told the ECU only uses around 10A. I used a 30A resettable breaker that you can see at the bottom of my last pic.

[BamaNomad]

[QUOTE=chevynut;68130]

The battery can be viewed as a giant capacitor, which smooothes out spikes caused by such things as alternators, starters, etc..[/quote}

I agree, but why does it matter if you have 10 feet of #10 wire to the battery or shorter lengths of larger wire? It still goes back to the battery.
...

I don't know either, Lazslo. I was hoping you'd run that experiment for us so we'd all know..