retrofitting 5.0L into 2000 mustang

hey everyone

I plan on ripping my 3.8L out of my 2000 mustang and replacing it with a 5.0L (still using the 3.8's 4R70W tranny) what I wanted some input on is I have 2 sets of wiring harnesses, one is from a 95 GT that had a AODE and the other is from a 90 GT that had a AOD. Ive heard that the 95's EEC IV is crappy performance wise (calibration U4P0) but since it was designed to control an AODE it should be able to control the 4R70W plus be fairly close wirng wise to the rest of my car, the 90's EEC IV (calibration A9P) is much better but has no provisions for transmission control, and obiviously be more work itegrating it into my car. should I go with the 95? or the 90 plus get some sort of stand alone transmission controller?

thank for your help


P.S. Anyone know anything about the PATS system and what to do to remove it when I change EEC's?
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New Member
Nov 8, 2004
Harrisburg, PA
I dont think pats will be a problem...remember, there is usually a pats module that is connected to the engine computer, or that function is integrated. but your other comp's dont look for that in order to start the engine. I would use the 95 harness, because of the trans control. yes, the later tune is sucky, but that can be fixed with a pms unit or a chip. or you can use the 90 harness, but you will need a ~$500 trans control unit.
Carbs????? Im on a NO CARB diet LOL

Hey guys

I am NOT a big fan of carberators and especially since this thing is going to have a eaton supercharger on it SEFI is the way to go, LOL so once again I pose the question if anyone here has an opinion, should I go with a A9P EEC IV and harness from a 1990 stang and use something like a bauman engineering controller for the 4R70W, or use a U4P0 EEC IV and harness from a 95 and try to work around the crappy programming in that EEC, also I am going on the assumption that the 95's harness should be closer to plug and play with my 2000, (basically because of similarities with dash and interior) over a 1990 set up, true or not true? would it even matter?

ooops LOL

sorry superhuman didnt see your response

so basically as far as your concerned you favour the 95's EEC because of the transmisson controls being built in? do you think the 95's is closer to being plug and play in a 2000 vs the 1990 harness and EEC? Ive got both set ups here although the 95 harness i got from ebay is kinda ratty, the motor I am building is kind of stout with a motorsport Z303 cam, 347 stroker, eaton M112 supercharger, sheetmetal intake, 42Lb injectors etc so I want a healthy management system that will put it all to good use, I suppose in either case Im either buying a tranny controller, or a PMS so basically I guess it falls to which is going to be closer to plug and play (if any LOL)

thanks for the help



Advanced Member
Sep 28, 2003
Indianapolis, IN
I assume u will be modifying it a lot...wont be a stock motor. That said, you will want a tune regardless as u'll want the max performance out of it. So with a tune on a 94-95 there is no "better" eec...matter of fact, the 94-95 is better or has more advantages in some applications.

So pick whichever eec will give u the least headaches on the swap, and just get a tune after. Yea stock, the eec isnt the best, but with a tune, all bets are off.


All my crevices are greased.
Oct 22, 2004
Arlington, MA
As long as you're putting a 302 in it, just add a hydraulic/cable pressure valved old school AOD. The cost of the AOD is the same as the prices the folks above have been rattling off just for a computer module for the 4R70W.

Just build up the aod with about $300 of parts and you're good to go.


New Member
Nov 8, 2004
Harrisburg, PA
nmcgrawj has a good point-youre going to need to tune either ecu for your engine anyway. so why not use the one that will control the trans also. yes, the 95 harness should be closer to the 2000 harness than the 90 would be. but you may still have to splice...i would recommend splicing the plugs from the 2000 engine harness onto the 95 engine harness, if this is necessary. no reason to cut up the rest of the car.
Cool ok then just one more thing....

thanks for all the advice guys I really appreciate it

I think I will got with the 95's EEC after all, now my only problem is the EEC harness I got from ebay isnt in the greatest of shapes, anyone got a line on one? also does anyone know if the injector harnesses and 02 sensor harnesses the same regardless if its a 302 HO or a non HO from like a older crown vic? I know the non HO has a diffrent firing order and that trucks at the very least are batch fire injected (not sure if all non-HOs are batch fire) or if any of that makes the wiring diffrent? any ideas cause I still need to source those 2 harnesses before I get started

thanks again

the injector harnesses are the same for ho and non ho i am pretty sure. trucks are batch fire, and cars are sequential, ho or not. so you cant use an inj harness from a truck, only a car. the inj. harness will be easy to find, the o2 harness will be hard to find. i suggest ebay again though.

Don 95Vert

Founding Member
Oct 1, 1999
Delaware, OH
The later 4R70W will have a different internal wiring (harness in the pan that connects to all the solenoids) arrangment than an AODE (94-95). From '98 up Ford used a plastic, one piece connector with an intergral TOT sensor. The other problem is you would need a 94-95 converter clutch solenoid - the later ones are of a different impedence and won't work right - the solenoid and/or the EEC will fry. If it were me doing it, I'd put a 94-95 CC solenoid in it, then use a 94-95 style internal harness on the VB. You will have to zip tie the plugs on the connectors because the shift solenoids and EPC solenoids won't have clips (new style) You'll also have to buy a TOT sensor and snap it ito the hole on the VB and plug it in. Once you do that you can just use a 94-95 tranny harness mated to a 94-95 main harness.

It may seem easier (and it would be) to use a Bauman controller. They DO work well, but you give up a lot of control with a Bauman. They are simple, but you lose a lot of flexibility in things like converter lockup.

The 94-95 EEC WILL need a chip to tell it the tranny has different gear ratios or it'll never be right. You also will need a chip to change displacement or load calculations will never be right and spark will be off. And if you do use a Bauman controller, you would need a chip to tell the EEC it does NOT control the tranny. Or use a Bauman with a T4M0 processor (manual 94-95).

WOW didnt realize all that

Hey Don thank you for all that detail........

OK I had no idea about all those diffrences in the transmission VS the AODE, maybe I would be better off with a built AOD and the A9P EEC IV and harness for engine management after all.... let me know what your thoughts are on using the 90 EEC harness in the 2000 stang, I was leaning towards the 95 EEC and harness only because I was under the impression it would be an easier swap due to similarities between the SN-95 and new edge mustangs, I only wanted to retain the 4R70W due to it already having the wide ratio gearset that AOD's do not have from the factory. I am assuming I will have to do a fair bit more wiring also to get rid of the returnless fuel system in favour of a regular return system so your input on this matter is of great importance to me.

thanks again

fuel system

nope, trust me ALL the 99+ cars are returnless wether they are V6 or V8
:( actually its easier to swap a 4.6L into my car than a 5.0L, the only thing thats easier about the 5.0L swap is that you can use the 3.8's transmission because they use the same bellhousing pattern, the way this is shaping up Im goning to have to rewire MOST of my car :O