What's up ford guys, I'm posting this thread to share the knowledge I've learned. First, I'm a chevy man, don't like fords, but don't hate them. But this thread is just to share information, to those who may try what I did, or who may b n the process, but mainly to correct a thread I seen stating, a 4.0 won't run with a 3.0 ECM. My project is a 99 3.0 ranger, that I converted over to 4.0 engine, 4r55e trans, from a 97 donor truck. If anyone has any ?s, doubts, or inputs please feel free to ask, or chime n. Although this project is not yet complete, I still hav one issue to address,but the truck does run an drive. Although y'all may no all this krap by now, an if so, let me no. But I feel I've made an achievement, and learned a lot more about fords. When I get a reply from this thread, I'll share my experience(night mare) with y'all. Thanks an God Bless

 

Good work.
Yes, the end of the swap often takes longer than the swap, "devil is in the details"

Not a common swap because engine and trans both need to be swapped, and as you said the computer and all the engine wiring.

3.0l averages 145HP and 4.0l 160HP but 4.0l does have alot more torque than most V6's.

Most choose the 5.0l V8 swap since the labor is basically the same and you need engine trans, computer and wiring.
5.0l is 215HP.

But still it is a good swap since it is basically a stock truck, no odd parts issues.

I drive and build Chevy cars(love the 2nd Gen Chevelles) and Ford trucks.
Chevy can't make a good truck and never found a Ford Car I liked to drive.
So I guess I like and hate them both equally, lol.

 

Yea, a V-8 swap would hav been sweet, but this was purchased s a flip. The only issue I'm having now, I hav power to ac comp, with 4.0 ECM. But when I swap over to 3.0 ECM, no power to compressor, an no power to low an high pressure switch either way. Keep in mind, 3.0 ECM is what came in truck... The swap may b a common swap, but I wish there would hav been more info on this somwhere, cause I changed all kind of krap, and I won't lie, when I purchased the truck, I carried stupid with me, the guy told me it was a 4.0, an I took his word never thinkin to actually check what it was. Little to my surprise, buddy of mine spotted it was 3.0 after I bought it along with buying donor truck. That's y I was forced to do the swap.

 

Yes, the A/C circuit on some models was passed thru the PCM(computer), this allowed the PCM to do two things, increase idle when A/C is on and to turn off compressor when more power is needed, i.e. wide open throttle when passing.

 

Thanks for ur reply back, now I'm no good at wires or understanding, but I forgot to mention, with the 4.0 ecm( an I did use 4.0 motor, 4r55e, 4.0 wiring harness) I hav constant power to the compressor, that's my biggest issue. I hav also noticed, wiring harness from the 4.0, has the plug for the compressor, an a separate wiring harness that ran from the power distribution from 4.0, has a second plug for the compressor. I'm tryin to figure out y the 4.0 truck had 2 plugs for the compressor.... An to reply back to the chevy comment, I think chevy makes a good truck, I've had many of them, along with high miles close to 300k, they run like a champ, an do what I ask, but I still can't knock a ford to much, as I do still own one, and hav seen some good ones. I just hate that ford thinks they need to change somthin every year, if it works good, leave it alone. But as long as I never hav to own another dodge, I'll b good

 

Just looking at a '97 Ranger 4.0l A/C wiring diagram.

Power for the compressor come from the heat control inside cab, and runs thru the pressure switches
Control--(purple)---clutch cycling switch--(red/yellow)--pressure switch--(dark Green/orange)--(splice here)--(dark Green/orange)---WOT relay--(black/yellow)---compressor

(splice here) runs to the PCM pin 41, 12v here tells PCM A/C is on.

WOT(wide open throttle) relay(in engine fuse box) is controlled by the PCM, pin 69, it allows the PCM to turn off A/C when driver wants extra power, WOT, pin 69 would be set as a Ground to activate WOT relay to cut power to compressor.

It also shows a Diode straddling the compressor connector, black/yellow(12v) and Black(GND) wires on both
............/--Diode----\
12v----/-Compressor--\----GND

'99 is wired differently
It has a compressor relay that was activated by the PCM, this relay was in the engine compartment fuse box
Heat control switch was connected to the PCM, not the pressure switches, so PCM activated relay when driver turn on AC
PCM also monitored pressure switches so they didn't pass power directly to compressor, it looks like they were just a Ground path, and if PCM lost the Ground on that path it would mean a pressure switch had opened, so AC wouldn't start.

Not sure how much of the wiring or AC parts were swapped over, but it looks like you could add a relay that the heat controller could activate, the pressure switches would be the Ground for that relay, and then pass the compressor power thru that relay.
You could keep the WOT relay.
The added relay would pass power to the WOT relay


I was a Chevy guy in high school, over the years I noticed Chevy trucks were nickle and dime'ing me to death, just nuisance stuff, door handles, window ****, buttons, also water pumps and starters seems to be an almost yearly issue.
I got an old beater Ford truck, straight 6 with 4-speed(granny gear) to use around my place, it was cheap and already beat up so didn't care it was a Ford, but what I did notice was that everything worked, and stayed working.
I got a newer Ford truck as a DD, figured old Ford was a fluke, lol, but darned if it didn't keep working, no busted nuisance stuff over the years, yes it did break down but not the daily/weekly stuff I had with chevy trucks.
That's just my experience over the years

 

Thanks for the info. I understand some of that, an what I don't, I'll run by the mechanics I hav n my pockets. With that an there knowledge, I'm sure we'll get it working... But really nothin was swaped, except compressor, which is the same as 3.0, an wiring harness with comp plug. High an low pressure plug r from the 99... So now I will elaborate on the swap so that maybe it will b useful to who ever.

 

The '99 3.0l's computer(PCM) ran the AC, thats the big deal, '97 4.0l PCM can't do that.

On the heat controller there would be a wire that ran to the 3.0l PCM, it would have 12v when AC is switched on, but its only a 5amp fuse so would blow if ran directly to compressor.
When '99 3.0l PCM detected this 12v it would close the Compressor relay, turning it on, and passing 12V 10amp power to compressor
The 2 pressure switches on the '99 A/C ran to PCM as well.

PCM------cycle switch---------pressure switch--------Ground

This looks to me like the PCM wants to see a ground or it won't start compressor.

So if you added your own relay to take the place of the '99 PCM it should work fine.

Relay coil:
heat control AC on wire(12v)--------Relay Coil------cycle switch---------pressure switch--------Ground

This way relay can't activate if one of the switches is open, so compressor is protected.

Relay power:
12v 10amp fuse-----relay load----------WOT relay in fuse box

When relay closes WOT relay gets power just like it did in the '97 setup.

 

Thanks for that info, making more sense now. I hav several machanic's in my pocket, I'll show them ur info, an I'm sure they'll b able to get it goin. I hav decided to go with the 3.0 ECM, that way I'm not changing out the mass air. The truck seems to run just fine with it, an seems to hav plenty of power, am tranny seems to shift like it should. I'll try an post later, all the fun I had with this swap. I tried to post yesterday, hit submit, an ain't got a clue where it was submited to.

 

Well the firing order is the same on both.
The MAF system can accommodate stroked 3.0l and cams, so higher air flow of a 4.0l shouldn't be an issue.

Ford changed the Cam sensors in the late '90's, from a 3 wire to a 2 wire, these were different types of sensors, not just 1 less wire, so as long as the 4.0l Cam sensor had the same sensor wiring as the 3.0l then that shouldn't be an issue either, and it is just a matter of swapping the sensor in any case.