Bronco Forum - Full Size Ford Bronco Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
61 Posts
Discussion Starter · #1 ·
I have any 86 5.0 that I want to replace with a 90 5.8. The thing that has me worried is the difference in the wiring harness. It doesn't look like I can plug the newer ecu into my 5.0 harness like you would be able to with a later 5.0 harness. Is this going to be a nightmare?
 

·
The Anti Yam!
Joined
·
22,674 Posts
You will have to swap pins in the 60 pin connector to match the 90 model Computer. All you need is a wiring diagram of the 86 and of the 90 and move the pinouts in the 86 harneses 60 pin connector to where they match the 90 model computers pinouts.
 

·
aka: kemicalburns
Joined
·
7,918 Posts
Gacknar would i have to do the same when i swap my 5.8 from my 88 into the 85 i just bought? i should i just reuse the harness from my 88, i just think it might be to short with the ecu mounted under dash near steering column
 

·
The Anti Yam!
Joined
·
22,674 Posts
kemicalburns said:
Gacknar would i have to do the same when i swap my 5.8 from my 88 into the 85 i just bought? i should i just reuse the harness from my 88, i just think it might be to short with the ecu mounted under dash near steering column
I would use the one in the 85 unleas it is damaged. Yes you will need to change some of the pinouts, just compare the wiring diagrams.

85 and 86 EFI trucks where oddballs when it came to there wiring pinouts. All 87 up S.D. trucks share the same pinouts.

You just have to swap a few wires thats all.:thumbup
 

·
Registered
Joined
·
61 Posts
Discussion Starter · #6 ·
just to be clear on this. Do I hook my 86 harness to the corrosponding pins on the 90 connecter and plug it into the 90 computer?
 

·
The Anti Yam!
Joined
·
22,674 Posts
mxzx said:
just to be clear on this. Do I hook my 86 harness to the corrosponding pins on the 90 connecter and plug it into the 90 computer?
Nope, just move the pins on the 86 connecter to the corisponding locations on the 90 computer (pined out like the 90 harness connector) then plug the repined 86 connecter into the 90 computer.
 

·
Registered
Joined
·
279 Posts
mxzx said:
just to be clear on this. Do I hook my 86 harness to the corrosponding pins on the 90 connecter and plug it into the 90 computer?
Not to cause any problems with this........
Why are you using the 1990 ECU?

A few months ago I helped a friend convert his 1986 from a EFI 302 to a EFI 351W,
He had got the engine from a 1994 Truck.
We reused the 1986 ECU and harness on the 351,
We had to change the distributor as he coudn't use the "remote TFI Module" style.

We also used the 302 exhaust manifolds since we got rid of all the emissions stuff (351 exhaust manifold feeds the EGR & the 302 doesn't).

The only problem we had was the AOD blew up from the linkages not being set up correctly,
other wise it all plugged in and worked flawlessly (and still does to this day!).
 

·
Registered
Joined
·
61 Posts
Discussion Starter · #9 ·
I thought that you needed an 5.8 ecu to run a 5.8 engine. If not why is there so many different part #s for ecu if one will run anything?
 

·
Registered
Joined
·
279 Posts
mxzx said:
I thought that you needed an 5.8 ecu to run a 5.8 engine. If not why is there so many different part #s for ecu if one will run anything?
I have no idea why Ford has so many different ECU's other than for emissions or something.

As for the 1994 5.8 that was swapped into an 1986 Bronco,
It is running using the 1986 302 computer,
all the wiring from the 302 and everything plugged right in (had to lengthen the coil power wires) and works correctly.
Lucky.... maybe :rockon , but it all works still.

The whole swap was easy, a "Plug & Play" conversion.
 

·
The Anti Yam!
Joined
·
22,674 Posts
Dragon said:
Why are you using the 1990 ECU?


We reused the 1986 ECU and harness on the 351,
it all plugged in and worked flawlessly (and still does to this day!).
You got lucky.

9 out of 10 times that doesn't work.

O sure, a 351w on a S.D. 302 compter will crank up and run, but usualy it has a horrable idle, surging and general driveability problems. This is mostly due to a change in manifold vaccume and general volumetric efeciancy.

But luckily for your freind the particular 351w he used has a manifold vaccume that was close to his old 302. I would imigine the 351 has a few miles on it and therfore has a slightly lower than original mannifold vaccume.

Your that 1 guy that it worked for. :thumbup
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top