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The Parts Guy
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Discussion Starter #1
What EEC wiring harness did you end up using? Did you use a Mark 8 EEC harness or your original Tbird/Cougar 4.6L EEC harness?

I'm in the middle of this swap into a 90 XR7. I have a 97 Tbird 4.6L donor car and a 94 Mark 8 donor car. I'm installing the dash (and door panels, etc) from the 97 4.6L Tbird, along with the wiring harness that runs down the driverside of the engine compartment (has the large fuse block, etc). I currently have the old 90 dash out, and I was about to install the Mark 8 EEC harness when I noticed a difference that may be important. There are two plugs on the EEC harness that are located inside the car (in relation to the firewall) that connect to two plugs attached to the dash. The Mark 8 ones are different from both the 90 3.8L dash and the 97 4.6L dash. Should I use the Mark 8 EEC harness and end up splicing (if the wires even match up) or should I use the 97 4.6L EEC harness? I've attached pics of the two plugs that I'm referring to. The top pic is of the 90 3.8L ones (similar to the 97 4.6L ones), and the bottom pic is of the 94 Mark 8 ones.





Thanks for any help/guidance,
Rod
 

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id like to know the same thing.....like if you need to drop 400 bucks on a whole new chip for the car....they should do a tech article on this swap....racecougar does the 97 have a good tranny on it?
 

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The Parts Guy
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Discussion Starter #3
Well for the setup that I will eventually be going with, a chip will most certainly be necessary.

One question I didn't even think to ask was which EEC should I use? I had assumed that I would use the 94 Mark 8 EEC, but I'd imagine that the pinout would be completely different in the 97 Tbird 4.6L EEC harness when compared to the 94 Mark 8 EEC harness. I'm not certain on this, as the correct wiring diagrams are still in the mail, I'll know more when they arrive.

-Rod
 

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The Parts Guy
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Discussion Starter #4
Thunderterd, 4 Cam Bird, Teeps.... where are you guys? I've been staring at old posts all night, so please don't tell me to search for my answer here. I didn't realize that in a Mark 8, the EEC is mounted on the driverside instead of the passengerside like our Tbirds and Cougars. Is that correct? I'd just like to hear your opinions on what course I should take. I've listed a few options below. I'm not at all certain if they are all possible, but please give me your opinions.

With all of these options, I plan to use the 97 4.6L Tbird dash and the wiring harness that runs down the driverside of the engine compartment (includes the underhood fuse box, etc).

I could possibly use the complete wiring harness from the EEC (and including the EEC) to the engine from the 97 4.6L Tbird, but then I would need to hook up a rpm activated switch to open/close the IMRC's.

I could use the complete wiring harness from the EEC to the engine from the 97 4.6L Tbird, but use the 94 Mark 8 EEC and add pins to the EEC harness for the IMRC's. IF I CAN FIND A 97 THUNDERBIRD WIRING DIAGRAM.

I could use the 94 Mark 8 EEC, EEC harness, and engine harness, and just be troubled with the two above mentioned plugs.

Any help is greatly appreciated. Until I figure out what to do with the EEC harness, I can't put the dash in, which is leaving me stuck with nothing to do.

-Rod
 

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racecougar said:
Thunderterd, 4 Cam Bird, Teeps.... where are you guys? I've been staring at old posts all night, so please don't tell me to search for my answer here. I didn't realize that in a Mark 8, the EEC is mounted on the driverside instead of the passengerside like our Tbirds and Cougars. Is that correct? I'd just like to hear your opinions on what course I should take. I've listed a few options below. I'm not at all certain if they are all possible, but please give me your opinions.

With all of these options, I plan to use the 97 4.6L Tbird dash and the wiring harness that runs down the driverside of the engine compartment (includes the underhood fuse box, etc).

I could possibly use the complete wiring harness from the EEC (and including the EEC) to the engine from the 97 4.6L Tbird, but then I would need to hook up a rpm activated switch to open/close the IMRC's.

I could use the complete wiring harness from the EEC to the engine from the 97 4.6L Tbird, but use the 94 Mark 8 EEC and add pins to the EEC harness for the IMRC's. IF I CAN FIND A 97 THUNDERBIRD WIRING DIAGRAM.

I could use the 94 Mark 8 EEC, EEC harness, and engine harness, and just be troubled with the two above mentioned plugs.

Any help is greatly appreciated. Until I figure out what to do with the EEC harness, I can't put the dash in, which is leaving me stuck with nothing to do.

-Rod

I put a 93 Mark engine in my 95 LX. Actually my friend that owns a local Mustang shop did the swap. He used the LX wiring harness & modified it where needed. I used the LX computer & had it reflashed to the Mark parameters. It wasn't that hard to do & there wasn't that much modification required. I used an MSD RPM window switch, tach driver & relay set up to operate the IMRCs.
 

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The Parts Guy
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Discussion Starter #6
Ok, so you used your complete original EEC harness, engine harness and EEC, and you just had to splice/lengthen some of the wires on the engine harness and add provisions for opening/closing the IMRC's (RPM window switch, etc)? Was that pretty much all there was to the swap for you? It sounds like I may possibly end up robbing more wiring (and the EEC) from the 97 4.6L bird than I had originally planned, but that is ok. That's what parts cars are there for.

Does anyone else who did the swap care to post? I'd really appreciate as much info as possible.

Thanks,
Rod
 

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I PMed you, it only took me a day, give people a little time, its a weekend, there's a lot going on, its summer time :).
 

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The Parts Guy
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Discussion Starter #8
I realize that, and I'm sorry if I came across as being "pushy". I'm just in a bit of a hurry, as I only have a week to get and install the front suspension, install the wiring, and install most of the interior (including the dash) before I leave town to go back to school.

I PM'd you back.

Thanks,
Rod
 

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Wow, you start school early.
 

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The Parts Guy
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Discussion Starter #10
At the moment (I'm allowed to change my mind), it looks like I will use the 97 4.6L Tbird EEC, EEC wiring harness, engine wiring harness, dash, and the wiring harness that runs down the driverside of the engine compartment. From what I've been told and read, everything will hook right up without any splicing or lengthening of wires. The ONLY thing that I should have to add is a provision for opening/closing the IMRC's, correct? I will also try to use as many of the sensors, modules, etc from the 97 4.6L Tbird, to keep things less complicated.

Does anyone see anything that I've missed, or have any helpful suggestions? I do know that the EEC will have to be reflashed, but I'm assumming that by taking the route that I am, that I will not need to splice or lenghten any wires or repin any connectors. Anyone know otherwise?

Thanks for all of the help, especially 4 Cam Bird, you've been extremely helpful,

-Rod
 
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