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Discussion Starter · #1 ·
I have a thread about this in the technical section but it doesn't seem like many people look through there often, and my post is getting cluttered.

Thus I am going to post this out here and see if I can get some better feed back.

Long story short, I have a JDM MK4 and I am putting in a USDM ECU. All other variables aside, where am I going to wire in the factory resistor pack I have for the injectors?

There are 7 wires, 6 red and black for the injectors and 1 yellow black for 12v ignition power I would assume. My question is where do I wire those single 6 black wires to. If you have pics that would be a GREAT help. If not maybe a little photoshop ot paint diagram sort of thing would be great too.

Thanks in advance for the help!

Jon
 

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Discussion Starter · #3 ·
"6 red and black for the injectors and 1 yellow black for 12v ignition power I would assume."

You are correct!
Cool I got that, however, I do not know EXACTLY where to wire those 6 in at. I need some specifics here please.
 

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Discussion Starter · #5 ·
One wire goes to eack of the injector clips. Remember to keep them uniform.
This seems simple to me but I guess I am missing something. The injectors have a 2 wire pigtail clip right? And I am assuming both are used and run into the wire harness for the motor.

The ECU has 1 output for each injector. Where exactly would I be wiring this? I am going to just have some original wires not hooked up? This isn't making sense to me.
 

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Disect the stock harness and cut each of the power (12 volt ignition) source which runs to each of the injectors pig tail. After thats done, pool them together and soilder them to the one yellow/black stripe wire.

Then each of the red/black stripe wire you`ll connect back to each of the injector pig tail.
 

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Discussion Starter · #7 ·
Disect the stock harness and cut each of the power (12 volt ignition) source which runs to each of the injectors pig tail. After thats done, pool them together and soilder them to the one yellow/black stripe wire.

Then each of the red/black stripe wire you`ll connect back to each of the injector pig tail.
FINALLY lol an explaination with a little better detail for me. Sorry i wasn't understanding it before guys.

Once more to double check:

I'm going to cut the factory injector wires going from the ECU seen below as E9 15-20 and I will soilder them all to the yellow and black wire on the resistor box harness.



I will then take each of the red and black wires on the box and wire them to a single injector, and it doesn't matter which injector it would seem.

And that's it????

Seems simple enough. Just want someone to double check me :)
 

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Please don`t make it harder than it is.

Just wire each injector with the red/black stripe wire and keep each wire on the same side... hence the word; uniform.

yellow and black gets the 12 Volts source from the main harness.

Good Luck
 

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Wiring up the injector

I think what is confusing for most regarding this upgrade is exactly what is doing what as it relates to the resistor module and the ECU.

The injector has two wires one power and one ground.

Based on the schematic it appears with ignition on, a constant source of power is fed to the injectors. We all know that power is pointless and the injector cannot fire if there is no ground connection. The ECU provides the ground signal, this is why you can't cut the wires from the ECU. You want to cut the power sides to the injectors.

I personally don't think you need to, once cutting the power wire to your injector, wire them all to the resistor - Yellow black wire. I think you need one source of 12v power to the resistor. Pulling it from one of the newly cut injector power sources is good. I say this because it is ignition controlled and fused. Cap the remaining wires making sure they cannot connect to any metal on the engine. This will cause power to ground and instant blown fuse. If the fuse doesnt blow, that wire will be destroyed due to the amperage flowing through it.

The resistor module should have seven wires, one which is a power wire in. This is the yellow and black wire mentioned earlier. The other wires should be wired to the injector individually. Their purpose is to provide power to each injector. Since the power source is constant you really don't have to worry about the order these connections are made in.

I hope this makes it clearer for those who follow and want to know how to wire in their resistor module.

Someone else may chime in on exactly what the point of the resistor box does. I know it has to do with how much amperage the ecu sees once pulling ground on each injector.

Once I actually perform this modification, I will do a brief write-up with pics.
 

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Wiring up the injector resistor module

I think what is confusing for most regarding this upgrade is exactly what is doing what as it relates to the resistor module and the ECU.

The injector has two wires one power and one ground.

Based on the schematic it appears with ignition on, a constant source of power is fed to the injectors. We all know that power is pointless and the injector cannot fire if there is no ground connection. The ECU provides the ground signal, this is why you can't cut the wires from the ECU. You want to cut the power sides to the injectors.

I personally don't think you need to, once cutting the power wire to your injector, wire them all to the resistor - Yellow black wire. I think you need one source of 12v power to the resistor. Pulling it from one of the newly cut injector power sources is good. I say this because it is ignition controlled and fused. Cap the remaining wires making sure they cannot connect to any metal on the engine. This will cause power to ground and instant blown fuse. If the fuse doesnt blow, that wire will be destroyed due to the amperage flowing through it.

The resistor module should have seven wires, one which is a power wire in. This is the yellow and black wire mentioned earlier. The other wires should be wired to the injector individually. Their purpose is to provide power to each injector. Since the power source is constant you really don't have to worry about the order these connections are made in.

I hope this makes it clearer for those who follow and want to know how to wire in their resistor module.

Someone else may chime in on exactly what the point of the resistor box does. I know it has to do with how much amperage the ecu sees once pulling ground on each injector.

Once I actually perform this modification, I will do a brief write-up with pics.
 

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Brief Write up

I have finally returned to finish what I started months ago when I was having a small challenge understanding what exactly it was I needed to do. With a little reading and the help of the wiring diagram I was able to figure out what was needed. I believe I explained in pretty decent fashion how the injectors fire in the previous posts.

I'll include a couple of pictures of my set up and say when possible I like to keep things as close to stock as possible. There are a number of ways one could go about getting to the same end goal. I like being able to unplug and replug and unplug etc.. So I went the extra step of ordering the wiring harness side plug and wire repair kit so I could splice the low impedance module directly into the harness but unplug it too. This is just my preference!

Here you'll see the plug and the wire kit I purchased. This will be spliced into the wiring harness. I chose to cut in right behind the cylinder head drivers side. Note I am driving a GS300, I assume the harness travels the same path on the supras. One other point, the #1 injector travels from the front, so you'll find all five power leads for 2 - 6 at the back corner and the #1 injector at the front drivers side. Just trace from the injector plug to through the harness you'll see.



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Here I have made the connections, cutting the power wire feed to the injector and capping the wiring harness side and splicing into the side that feeds the injector. I used solder and heat shrink for the most reliable connection.



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Note because I swapped out the GS300 drivetrain for a JDM Aristo drivetrain I had to also change the injector clips. That is after all the whole point of this mod at least for me. Moving from a 440 cc injector(jdm) to a 550 cc injector(USDM) which requires the low impedance module due to the impedance of one injector compared to the other.



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Here I am showing you the wire loom after splicing into the stock harness. I chose to mount my impedance module on the strut tower drivers side.



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Here is the finished product, looks close enough to stock for my taste



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Just one more shot of the new injectors and my work area;



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Just a personal preference and for those who follow happy wrenching and much success.
 
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