84 B2 2.8L swap to 92 4.0L - transmission and wiring questions

[Bronson with Bronco]

Hello all. I've really enjoyed the articles here and have benefited greatly from them. I've owned a number of classic Broncos through the years, and more recently purchased a 1984 B2. Long story short, but after a couple of years of owning it a nut went through the intake, smoked a valve, and smashed a piston. I'm now researching my options, and haven't been a fan of the 2.8L, so am looking at possibly upgrading to a 4.0L.

I found a 92 Explorer 4.0L that I may be able to use as a donor vehicle. It has a low miles 4.0L that is in running condition, a bad auto transmission, but is otherwise good and complete. I've read everything I can find, but still have some lingering questions.

First, my B2 has the 5 speed manual, and I'd like to keep it that way. If I swap in the 4.0L and wiring harness from the Explorer with the auto trans, will this create problems? If so, is there a (simple) solution?

Second, I've read quite a bit about the dash swap. I'm really not interested in swapping the entire dash from the 92 Explorer. Is it possible (and reasonable) to wire in the 4.0L harness to my original dash?

Thanks for any help you can offer.

Ben

 

[franklin2]

Can you think of anything in the dash that would need to be hooked to the later computer system? Besides the check engine light, which your BII doesn't even have. You may be able to find a spot for it.

I am in the exact situation now that you are in. I have a 84 BII and was using the 2.8, till the throttle stuck wide open during a shift, and after some back firing will not run. I have a 2.9 waiting in the wings in excellent shape, and am planning to swap it in place, fuel injection and all.

I have all the wiring diagrams, and it looks like there are some critical power wires with fusible links, and some ground wires. The 86 2.9 I am using did have some wires for idle strategy that go throughout the harness to the clutch pedal, the transmission shifter, etc. I am going to experiment with this and see if I need it. The later setup you are going use, uses the speed sensor for this. Which brings that up, I think you might need a speed sensor that fits into the speedo cable on yours, my older 86 system doesn't have a speed sensor.

But as far as the rest of the wiring, it has nothing to do with the engine and the computer system. It's all separate. You can save and use the oil pressure and temp wires for the gauges, and use them on your 4.0, but they will just pull out and lay on the fender till you get the 4.0 in place.

I had to think about the fuel system a little bit. First off, I am going to need a new fuel tank, I suspect you will also. Our carbed fuel tanks have a small hole with a sending unit with no pump. My 86 system uses a frame mounted high pressure pump, and then a low pressure pump in the tank. I am going to order a new fuel tank for a 1986 Bronco II, and a new fuel pump/sending unit. That should take care of that, though I haven't figured out the wiring yet. Not sure If I will need to unwind the fuel pump wiring out of the rear lighting harness. My donor is a pickup, and all the wiring runs on the frame rail. The Bronco wiring runs inside in the body.

You may run into a problem with your fuel system. Do some research on it. I was thinking about converting my fuel system to one fuel pump in the tank like the later ones are. But Ford changed the way the fuel gauge and sending unit work around 1987 or 88, so anything later will not work the fuel gauge properly. The reason why I am just sticking with the two pump system. Unless you have a solution for this?

 

[RonD]

Welcome to TRS

Good page to Bookmark here: https://www.therangerstation.com/tech/

Select the Engine section
Then scroll down to V6 engine swaps, lots of "been there done that" information

As frankin2 said you are going from a 5-7psi Carb fuel system to a 30-40psi EFI fuel system
So you will need to add a Return fuel line and 12volt power for an in tank fuel pump
But you need to keep your current in tank Sender and float if you want to use the 1984 Dash fuel gauge
Ford change the fuel gauge and senders in 1989
There is a window of 1986-1988 that used Return line and same senders and in tank fuel pump with a 2nd external fuel pump for EFI

Temp gauge on dash will work with 1992 4.0l 1 wire temp sender on engine

Oil pressure gauge was a real variable sender on the 1984 2.8l so that sender can be install on the 1992 4.0l in place of its oil pressure "switch"

You may have a Charge/Discharge gauge instead of a Volt meter on the dash
The 1984 alternator wiring will have a "Shunt" setup on the B+ wire that runs to Battery positive
You can cut this out to use on 2G or 3G alternator

A Shunt
Say the wire from B+ to Battery positive uses 12gauge wire
You would cut that wire and install say a 6"-8" 14gauge wire between the two cut ends
And at each of these splices you would also install an 18gauge wire, these 2 wires would run through the firewall to the "AMP Gauge"

Because of the slightly higher resistance in the 14ga wire some of the alternator's AMPs will run through the 18ga wires and thru the AMP Gauge and back to B+ wire, its not much but enough to show + ,charging
If alternator should fail the AMPs come from the Battery end of B+ wire so would show up as - , discharging

AMP gauges were used on alternators with external voltage regulator and Generators
Voltage Gauges were used once alternators got internal regulators because they were MUCH EASIER and cheaper to wire, lol

+1 on adding a CEL(check engine light), a must have for trouble shooting
You may have an "Emissions" bulb on the dash you can use
CEL comes on with key on, means computer has powered up
CEL goes off when cranking engine over, means computer is getting a good timing signal from EDIS6 spark module
And of course, CEL comes on when driving if any Trouble Codes have been set

 

[gaz]

@Bronson with Bronco , @franklin2 ,
Swapping a 1st gen Explorer 4.0 into a 1st gen Ranger/BII presents more issues than a 2nd GEN Ranger/BII. I am swapping a 1st gen Exp into a 1st gen BII. While I adore the character of the 1st gen dash, I decided to side step the rewiring for the dash/column/firewall job with a complete cab/engine bay wire harness swap...no splice.

 

[franklin2]

@Bronson with Bronco , @franklin2 ,
Swapping a 1st gen Explorer 4.0 into a 1st gen Ranger/BII presents more issues than a 2nd GEN Ranger/BII. I am swapping a 1st gen Exp into a 1st gen BII. While I adore the character of the 1st gen dash, I decided to side step the rewiring for the dash/column/firewall job with a complete cab/engine bay wire harness swap...no splice.

What is there to re-wire? I am asking without researching, but if the 1st gen exp fuel injection will work by itself, the old BII dash will certainly work by itself. I would think you could carefully find the power supplys and grounds to the fuel injection, and wire them in. And it should go? Of course you still have the speed sensor to add in.

As far as the old ammeter wiring, it's not worth the trouble. They never worked that well when they were new, so I would not worry about the shunt wiring. You could run the charge wire from the newer alternator straight to the battery +. The 84 has a + supply wire that runs the whole truck hooked to the starter relay + connection, and then runs around the front of the radiator to the driver's side where it picked up the old original alternator and regulator which is mounted over there. That can be cleaned up with a little bit of study, you do not need the old regulator and the rest of that wiring. But you do need to splice the wires together so it can go in the cab and feed the electrical system.

 

[Bronson with Bronco]

Welcome to TRS

Good page to Bookmark here: https://www.therangerstation.com/tech/

Select the Engine section
Then scroll down to V6 engine swaps, lots of "been there done that" information

As frankin2 said you are going from a 5-7psi Carb fuel system to a 30-40psi EFI fuel system
So you will need to add a Return fuel line and 12volt power for an in tank fuel pump
But you need to keep your current in tank Sender and float if you want to use the 1984 Dash fuel gauge
Ford change the fuel gauge and senders in 1989
There is a window of 1986-1988 that used Return line and same senders and in tank fuel pump with a 2nd external fuel pump for EFI

Temp gauge on dash will work with 1992 4.0l 1 wire temp sender on engine

Oil pressure gauge was a real variable sender on the 1984 2.8l so that sender can be install on the 1992 4.0l in place of its oil pressure "switch"

You may have a Charge/Discharge gauge instead of a Volt meter on the dash
The 1984 alternator wiring will have a "Shunt" setup on the B+ wire that runs to Battery positive
You can cut this out to use on 2G or 3G alternator

A Shunt
Say the wire from B+ to Battery positive uses 12gauge wire
You would cut that wire and install say a 6"-8" 14gauge wire between the two cut ends
And at each of these splices you would also install an 18gauge wire, these 2 wires would run through the firewall to the "AMP Gauge"

Because of the slightly higher resistance in the 14ga wire some of the alternator's AMPs will run through the 18ga wires and thru the AMP Gauge and back to B+ wire, its not much but enough to show + ,charging
If alternator should fail the AMPs come from the Battery end of B+ wire so would show up as - , discharging

AMP gauges were used on alternators with external voltage regulator and Generators
Voltage Gauges were used once alternators got internal regulators because they were MUCH EASIER and cheaper to wire, lol

+1 on adding a CEL(check engine light), a must have for trouble shooting
You may have an "Emissions" bulb on the dash you can use
CEL comes on with key on, means computer has powered up
CEL goes off when cranking engine over, means computer is getting a good timing signal from EDIS6 spark module
And of course, CEL comes on when driving if any Trouble Codes have been set

Thanks for the warm welcome.

I've read through the tech section and engine swap articles, but it seems that most of what I read is about wiring the 4.0 to a B2 that was running the 2.9. Not sure how different it will be going from the 2.8.

I'm already running an electric fuel pump mounted at the tank, so 12v power isn't an issue, and the rest of the fuel system seems like a fairly low obstacle to overcome.

The dash gauges seem doable, and adding a CEL should be easy enough.

Where I've read about the large cluster of wires through the firewall, is that specific to a full dash swap?

I'm grateful for such a good response to my post, which encourages me in taking this project on - looks like lots of experience and wisdom here, and a willingness to help.

 

[Bronson with Bronco]

The 86 2.9 I am using did have some wires for idle strategy that go throughout the harness to the clutch pedal, the transmission shifter, etc. I am going to experiment with this and see if I need it. The later setup you are going use, uses the speed sensor for this. Which brings that up, I think you might need a speed sensor that fits into the speedo cable on yours, my older 86 system doesn't have a speed sensor.

I'm not familiar with what the 4.0 brain will need in terms of speed signal. Can you point me to where I might learn more about this? And, high level, will the 4.0 with harness from an auto trans work with my manual transmission?

Thanks much!

 

[franklin2]

I can't find the article, but I remember what it looked like, I looked up a 89 Ford ranger speed sensor and the Dorman 917-614 looks like what they had in the article. I have never messed with this, but it looks like it plugs in where the speedometer cable goes, and then the speedometer cable plugs into it. Not sure if you can find a pigtail to fit it, I would think someone would sell one.

You most likely could use the auto ECM with your setup, but you would have a continuous check engine light when it saw there was no transmission sensors hooked up. That might be a later revision, finding a manual 4.0 ECM after you get it running.

 

[Bronson with Bronco]

Alright, I'm at the starting gate. I purchased and trailered home a '92 Explorer 2 door 4wd with the 4.0L. Engine is out of the Bronco (Little Brown Deuce), garage is straightened up and ready to get messy again. I'll probably pull the Explorer engine in the next couple weeks, then it'll be off to the races.

I plan to eventually swap the axles as well, but the first priority is getting the Little Brown Deuce back on the road, as we typically rely on it to get around in the snow during our winters.

 

[RonD]

And the Adventure begins

 

[Bronson with Bronco]

+1 on adding a CEL(check engine light), a must have for trouble shooting
You may have an "Emissions" bulb on the dash you can use

I've looked through the wiring diagrams for the 92 Explorer and haven't come across the wiring specific to the check engine light. Do you know where it runs, and what color wire it was going through the firewall? Would it be as simple as finding that wire, extending it through the firewall, and adding something like this to the end of it?

 

[franklin2]

I attached a diagram that has the check engine light.

 

[franklin2]

I am in the middle of my swap now also. It's a little bit of a hassle. "Most" of the fuel injection harness is separate, but there are important wires imbedded in with the regular chassis harness. One I have been messing with so far is the fuel pump wiring. They incorporated some of this harness with the lighting harness running to the rear. So I will have to separate these wires out of that harness, so I can use the connector on the sending unit. I may end up splicing these wires and making them longer anyway , along with the fuel lines. The Bronco is shorter than the truck, but the tank is in the rear. The truck is longer, but the tank was midship. So it will be close.

I am also finding other wires under the hood inbedded in the other harness. Of course you have the simple power and grounds to the computer, and power to the ECM relay. But you also have key-on power coming from the chassis where it goes eventually to the key, and also a start signal wire tied into the solenoid circuit.

I found the wire to the A/C relay which I am not going to need also. You definitely need the diagrams of both vehicles when doing this.

 

[Bronson with Bronco]

Thanks, @franklin2

 

[RonD]

A CEL Bulb gets 12volts from the instrument cluster with key on, but bulb is not Grounded so stays OFF
When the computer(EEC) powers up, also with key on, it will Ground the CEL bulb turning the CEL on, which means Computer has Booted up OK

Pin 17 on the 1992 Computer's 60 pin connector is that ground for CEL bulb

Computer was usually in the cab, in passenger kick panel area, and it's wiring harness ran thru the Firewall on passenger side of the engine bay
On that main harness, in the engine bay, is the OBD1(VIP) test connector
Its where you would plug in an OBD1 Reader

Looks like this: https://www.therangerstation.com/tech_library/images/eec-iv_testing2.gif

A 6 slot connector and a single slot connector
On the 6 slot connector the Self-Test OUT is the CEL ground from pin 17
So you could "tap"/connect your added light there, run a wire from this OBD1(VIP) slot thru the firewall into the cab
Mount your light and connect it to a 12v key on power wire, and to the new wire

Some newer lights are LED, so have a + and - wire unlike "regular" 12v bulbs
Test any new bulb on your battery terminals to makes sure it lights up with either wire on either positive or negative