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Couple swap questions

I have an 87' GT that I've pulled the drivetrain from and am going to do a 4.6 2v swap. So far for the drivetrain, I've acquired a T-45 from a 99' GT and an engine wiring harness from a 99' GT. Aside from the ECU harness, are there any other harnesses I need? Is there a difference between an MT and AT ECU harness? Is there a specific year ECU I should look for?
Is the easiest way to go about the fuel system, to just swap some 96-98 fuel rails and keep my fox body fuel system in place?
I left the body harness in place in my fox body. It sounds like the easiest way to make this work, is to make the 4.6 harness a stand alone system with a few splices into the fox body harness for power, ground, etc... is that correct? Also since I'll be leaving all the fox stuff in, when it comes to PATS, do I just get a handheld tuner that has a tune built in it with PATS turned off?
 

Bill

Well-Known Member
Staff member
Donator
Welcome to the party. Dig in and make yourself at home. Start a build thread so we can all follow :) I would recommend you source all of your electronics from the same year donor. It makes chasing gremlins much easier. All of your answers are on this site, including wiring diagrams. There are multiple ways to do virtually everything and many of them are shown here in the build threads. For my personal builds, I have used the entire fuel system from the donor car. You can use the Fox system. I think there are a couple of threads on here that show that. I look forward to seeing your build.
 
What are you going to tune with? That should be a factor. You can NOT turn off pats with hand held tuner alone.

There is a difference between AT/MT computers but you can use them both, you will need to tune them.

You will want a harness from the same year as computer, some of the pin outs differ slightly.

98 is weird year for fuel systems

99+ is returnless fuel system

Not sure what the best option is for you I think the 96-97 are the best to start with but you have limited tuning options. I chose to go stand alone for this reason.
 
So I went with an ECU out of an 04' GT m/t. I used the engine harness from a 99' GT, and the ECU, starter, and fuse box harness off an 04' GT. I also had a dash harness from an 04', but I trimmed it down to just the datalink connector. I kept the body harness from the fox.
I got the ECU wired to where it's basically a stand alone system. I had a tune written to disable PATS and run the fuel system as a return style, along with the other basic stuff added in a performance tune. I was able to upload that tune through the datalink connector with an SCT X4 device.
The problem I am currently experiencing is that the fuel pump driver signal from the ECU is only sending 6V. It doesn't seem to be sending the 12V upon turning the key on, and then dropping to 6V like it should be. I'm looking at pin 40 of the ECU, which is light blue/orange as the signal wire, and pin 80 of the ECU, which is white/red, as the ground signal. I'm sending the power signal wire to the red/black wire on my old fox fuel pump relay, and the ground signal wire to the tan/green wire. No luck yet. I don't think the relay itself is bad. Does this fuel pump wiring sound accurate?
 

massacre

Well-Known Member
Donator
Don’t those model years use a CCRM and FPDM? Constant control relay module, and Fuel pump driver module?

3977

3978
 
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