96 4.0 to 90 Bronco II Swap Guidance

[RedB2]

Good Morning,

I was able to pick up a 96 explorer 4.0 for a good deal the other night. Rebuilt about 30k miles ago, good runner, and cheap. What I didn't realize was that 96 explorers had swapped to OBDII and some of the wiring and sensors are different. Unfortunately I only got the engine and engine harness, but no other wiring or computer. (I don't have enough room at my place to pick up an entire donor vehicle)

I can get the computer off rock auto, but finding the rest of the harness may be difficult. I've been reading through the FAQs trying to fully understand this project. Am I going to run into significant issues trying to get this engine wired up? Has anyone swapped one of these particular engines in their vehicle? I'm totally new to this, so I'm just looking for some advice before I start pulling my tired 2.9.

Also, I didn't get the motor plate that goes between the engine and trans (manual). Can I reuse the one from my 2.9 and manual trans I have now?

Appreciate any help!

 

[RedB2]

I've been reading through a bunch of threads trying to figure this out. I think I might have answered it in this thread http://www.therangerstation.com/forums/showthread.php?t=167469

Quote from RonD

1990-1994 4.0l Ranger manual trans computer(EEC-IV/OBD1) and wiring harness would be the best choice.
2.9l M5OD trans will bolt to the 4.0l engine, use 4.0l clutch parts.

2.9l would use a MAP sensor on the firewall as main air/fuel sensor, 4.0l used MAF(mass air flow) sensor on the air cleaner box.

In 1995/6 4.0l MAF sensor changed from 4 wire to 6 wire, the IAT(intake air temp) sensor was taken off the upper intake and moved to the MAF sensor, the extra 2 wires.
The 1997 won't have the IAT sensor on the upper intake, but the 1994 and earlier wires for it will be there at the upper intake, you can use a 6 wire MAF sensor and just reroute the 2 IAT sensor wires over to the MAF and connect them there.
You will need the 6 wire MAF connector as well because 1990-1994 wiring harness will have the 4 wire MAF connector.
Or you could change the upper intake, take 1997 upper intake off and replace it with 1994 or earlier upper intake, and use 4 wire MAF sensor, then wiring would match.

4.0l never used a distributor, 1990-1994 used an EDIS-6 module, 1995 and up had the newer Ford computers(EEC-V/OBD2) that had the EDIS module built in.
Older EEC-IV has 60 wires, newer EEC-V has 104 wires, EEC-IV is less complicated for 1989 since that is what you have now.

Google: EDIS-6
To see what it looks like, it is usually on the Rad support front or back side and it is plugged into engine wiring harness

Sounds like this is pretty doable. Will the sensors on the 96 engine still work with the earlier harness (minus the noted MAF sensor noted above)? I don't yet have the M5OD trans (currently FM146). I want to leave that trans in there for now so I can at least get the Bronco driveable and finish the trans swap later. Hopefully all the 4.0 clutch parts are compatible between the two trans? I don't want to buy things twice.

I know I have a lot of questions, but I'm getting them answered little by little until I dive in

 

[BlackBII]

The 4.0 flywheel and clutch will work with the FM146. The trans probably won't last long, but if you take it easy I'm sure it would be fine for making sure the 4.0 runs/drives fine until you can find an M5OD.

The absolute easiest way to do this swap is with a '90 Ranger 4.0 harness. It will be 99% plug and play. So if you can find one, that would be ideal.

If you will be sourcing pieces of the harness(s) from junkyards, try to find 90-92 Ranger/Explorer, as they have more in common with the 90 BII than the later years; 93-95.

If you are feeling adventurous, you could swap in a 96 Explorer harness and dash into your BII, and it would be all plug and play save for a few things like tail lights and fuel pump, and you would get OBDII in the process.

The sensors on the engine should all work fine with an older OBI harness, once you figure out the intake air temp and maf sensors.

 

[RedB2]

Thank you! I think this does help clear things up. I was able to locate a guy parting out a 1992 Explorer. That's the closest I've been able to find so far. I can at least grab the harness from him, but still need to locate a computer.

 

[BlackBII]

Thank you! I think this does help clear things up. I was able to locate a guy parting out a 1992 Explorer. That's the closest I've been able to find so far. I can at least grab the harness from him, but still need to locate a computer.

That should work. I would grab the entire engine bay harness; from the big plug on the drivers side firewall, over the engine, to the power distribution and down through the firewall to the computer.

You may have to repin a few wires on the big plug on the firewall, and also repin some of the connectors on the drivers side inner fender; there's usually two round or one big square. The wires are all the same color, but the plugs are different from the Explorer to the BII.

If you need some wiring diagrams I have the 1992 Explorer ones. I might have the 1990 Bronco II ones as well, I'll have to check.

 

[RedB2]

If you have both, I’d love to get a copy so I can start studying them!

 

[BlackBII]

Here's the 1992 ones I have

1992 4.0

1992 Body

 

[RedB2]

Here's the 1992 ones I have

Thank you! This helps a lot!

 

[BlackBII]

Thank you! This helps a lot!

I looked in all of factory manuals and found the pinout diagrams for everything but the large firewall plug.

When I did a '93 - '89 BII 4.0 swap years ago, I remember a few things not working, like the wipers and other little stuff. The large plug on the firewall was mostly the same between the two.

The power door locks, windows and speakers are another matter; they run through the fenders and up by the headlights.

Here's a bunch of better diagrams, they may help with wire colors and such. These are all 1992 Ranger and Explorer specific wiring diagrams, but most '89-94 or so RBV's will share some of these.

 

[BlackBII]

Here's some '90 ones

 

[BlackBII]

Once you get the 4.0 in place along with it's harness, power distribution and computer, I would plug in the firewall plug and see what happens. Most components will probably work but you can take the things that don't one by one and use the above diagrams to figure out what's going on.

You'll probably have to get some fuel lines from the fuel filter forward. I would also take this opportunity to replace/check/clean all of the grounds. There's one on the passenger side framerail that gets nasty, and there's one that goes from the back of the drivers side head to the firewall. There are a bunch on the inner fenders and radiator support as well.

 

[RedB2]

Wow! Thanks for the gold mine of diagrams and advice! I'll keep this thread updated with my progress

 

[RedB2]

Well I might be in a bit of a pickle. I'm very close to finally putting this 4.0 in my B2, but I was doing some more reading on the 4.0 tech page and it looks like my mismatch of parts isn't going to work. My engine is from a 96, but I have a complete harness and computer from a 92 Explorer. I thought the engines are the same apart from the plastic intake, but I guess the blocks, heads, and cams are all slightly different.

From my understanding, if I use the older computer on the newer engine, it won't provide the right fueling for it and could cause damage in short term. I could grab a computer from a 95 (96 was OBD II and I don't want to do that conversion) since the heads were the same those years, but fearing I'll now run into wiring harness compatibility issues. I'm kinda at a loss and venting. Wish I would have done a little more research before buying parts. Guess I got to excited Maybe I could have my current ECM reprogrammed for the newer engine? I don't know anyone who does that though. OR should I sell this engine and attempt to find one from a 1992?

Edit: I forgot I do have the upper intake from the same 92 explorer which I could swap, but not the fuel rail and injectors. If I found those two components, would it still work? Looks like I will need to remove and block off the egr valve as well.

 

[BlackBII]

They did change the heads and pistons in '95 to flow better, but your '92 computer should be able to run that engine just fine. You could use the plastic intake if you wanted to, you'll just have to add a spot for the intake air temp sensor, which wasn't part of the MAF in 1992.

The 4.0's all use the same 19lb fuel injectors and the MAF should be able to account for small differences in the head castings.

Does the engine have egr? You'll want to remove and block that off as the 1992 computer and harness won't have that.

 

[RedB2]

I think it does have an EGR, but will double check when I get home. I believe I can use some block off plates from my 2.9 for that.

I read this note in the 4.0 rebuild section which sent me into a slight panic lol

All of these engines had the same compression ratio whether they came with the original heads with the open chambers or the newer ones with the heart-shaped chambers, so they would seem to be interchangeable, but the computer calibration that was used for the old-style heads with the open chambers will not work with the newer heads with the fast-burn chambers. In fact, “It will burn the engine down in a few thousand miles,” according to a Ford engineer who worked on this engine program.