[Warhorse281]

Hey guys! Long time lurker, first time member/poster. Ok here's the deal...I have an '03 gt 5-speed and the motor took a dump on me. After calling around and touching base with some local mustang buddies I came across a 04 Mach 1 auto that's been wrecked and I can snatch whatever I need. After doing countless hours of reading I'm still confused so... WHAT ALL DO I NEED!!! I've read use the ecu and engine harness but keep my firewall and dash, or hack my stuff up and go, throttle and cruise cables, everyone has their opinion so guys, help me here. End all be all parts list so I can do this.

[Warhorse281]

To clearify, I know all about the coolant parts stuff, crossover, T-Stat, hoses etc. Mainly just confused as $h!t about wiring. Like can I just simply plug the Mach engine harness to the firewall harness and swap ECU's and roll. I've already got the PATS part taken care of if that's the case.

[WickedSnake00]

If you can pull the ECM, do it. Then you won't need any wiring or a re-tune. Since you've got a donor it should be a piece of cake.

[Warhorse281]

When you say no need for wiring are you implying none at all or the engine harness and ecu combo like in my second post. Sorry If I'm asking to be spoon fed, the donor car is about 3 hours away and the nearest tune shop is about 2 hours away. Perks of living in BFE... I just have pretty much a one shot at getting EVERYTHING and want all my ducks in a row.

[WickedSnake00]

Originally Posted by Warhorse281 When you say no need for wiring are you implying none at all or the engine harness and ecu combo like in my second post. Sorry If I'm asking to be spoon fed, the donor car is about 3 hours away and the nearest tune shop is about 2 hours away. Perks of living in BFE... I just have pretty much a one shot at getting EVERYTHING and want all my ducks in a row.

My suggestion is that you pull as much of the engine as possible. Basically disconnect the hoses at the radiator, disconnect the PS, disconnect the A/C, disconnect the hoses to the heater core, unplug the harness from the ECM, and pull that bad boy. (Of course you need to detach the mounts, starter, midpipe and U-joints as well.) Then take the ECM out and take it with you.

And when in doubt, pull it out. Better to have more parts than you need than not enough.

[Warhorse281]

That's pretty much the plan. I was just curious when install comes what parts could be universal plug and play. Like the engine to ECM harness connection, is it truly plug and play or am I gonna have to install the ECM side harness too. Since I finally bit the bullet and joined up I figured I might do a write up when time comes. I'm just praying for a clean, painless install. Then I can come and play with my big brothers in their 4v's.

[GripGrizzly]

Told you.

[WickedSnake00]

Originally Posted by Warhorse281 That's pretty much the plan. I was just curious when install comes what parts could be universal plug and play. Like the engine to ECM harness connection, is it truly plug and play or am I gonna have to install the ECM side harness too. Since I finally bit the bullet and joined up I figured I might do a write up when time comes. I'm just praying for a clean, painless install. Then I can come and play with my big brothers in their 4v's.

Everything is still Mustang and modular though. In fact I plan on using my GT ECM for my Cobra motor.

Expect lots of headaches though. I know I am, and I've already run into my fair share just piecing things together.

Good luck with the writeup. We'll have to see who gets their project together first, you or me.

EDIT:
Waaaaaaaaaait. Slight issues.
Are you pulling the engine with the transmission? If not you will need to swap over your flywheel/clutch, and you might be better off keeping your ECM. Auto ECM's "look" for a TCM (with the auto trans), and if that isn't there, it throws a code.

[Warhorse281]

Nah, I'm staying with my manual tranny. I'm not going to a slush box. And if a code is all i'm worried about there then so be it. I can ride with a CEL on 'til I can take it to the speed shop.

[Serlin]

Originally Posted by WickedSnake00 And when in doubt, pull it out.

Good advice on many levels

[8URSRT]

My '01 GT has a '04 Mach 4-valve w/Eaton swap. It is running off the factory GT computer but, the 4R70W was also retained.

[WickedSnake00]

Originally Posted by Warhorse281 Nah, I'm staying with my manual tranny. I'm not going to a slush box. And if a code is all i'm worried about there then so be it. I can ride with a CEL on 'til I can take it to the speed shop.

Well you should be fine, you'll just have to plug in your transmission harness, transfer over the flywheel/clutch assembly, and get a reflash.

I think the code is a P700 regarding the TCM.

I know with autos if the TCM isn't recognized it will throw it into limp mode and won't let you shift out of a certain gear, but I don't think that will be an issue with a manual.

[Warhorse281]

Awesome Possum. You guys have been a big help, thanks for the info. Oh and Wicked, I'm starting the swap next weekend.

[GripGrizzly]

Stop googling, and get ready to bleed some more over this Mustang.

[Warhorse281]

Ok little update. After calling around I have definitively found out that the Mach engine harness will not work with the GT firewall harness. So, looks like I'll be modifying my 2v harness and using my GT ECM. Now, if someone has done this already (and I know a lot of people on this site has) Please, pretty please with a blower on top... Contact me. I need some one to clear up what wires need to be lengthened, swapped, etc. I have the Mach engine harness so I'll be able to steal the connectors/wires off it, just need someone with personal experience with this to kinda walk me through it.