88' 5.0 HO/5spd in 91 4cyl/auto

[colorado456]

Hi Guys,

In the middle of my swap. I need some help! lol

Both engines/trans are out.

I have swapped engine harness, trans harness, front head light / alt harness.

Havent installed the 88 V8 yet.

I been reading about different year engine harness' not working with other year main harness' etc etc

Any help is appreciated!

 

[wewfords]

yea it true u need the all the wire for the pcm and the pcm thats all theinfo that i know about the swap

 

[lancec2c30]

I swapped an 87 5.0 and t5 into my 92 4 cyl. auto.

I want to say 91 harness is different from the 92/93, and 87-89 harnesses. I found a 93 harness and maf when I did my swap.
But you might need to find another 91 5.0 harness. Unless you want to swap the interior wiring out too.

Your o2 harness should be compatible as well. As long as your going from auto to 5spd.
There are some conflicting setups that require changing the pin out in one of the plugs, to avoid frying a circuit in the ecu.

 

[ID89GT]

You will need the correct computer and computer harness that runs along the firewall. Other than that it should all work for ya.

 

[MikeR351w]

I performed this swap as well. I did an 87 2.3L to a 92 5.0. For you, the dash harness should be swapped as well. The stock 91 gauge cluster probably wont work for your swap for a variety of reasons. Some of them being your airbag, the speedometer and a different gauge configuration. I tried using my 87 gauge cluster when I swapped to a 92 engine and it didnt work. Its easiest to just do it all at once. If your 91 engine harness has the WOT and fuel relay switch in the engine bay then, you will run into problems because the 88 harness has the fuel relay under the drivers seat. This would cause there to be two fuel relay switches and the pump wont turn on unless one is bypassed. Also, dont forget to get that extra vaccum canister in the passenger side fenderwell! You need that too. If you take the dash out, replace the heater core and a/c condensor

 

[colorado456]

Thanks for the replies!!

I am now replacing the dash harness, engine harness, headlight harness and trans harness.

Lance:
Could you explain the pin changing in the plug??

Mike:
I believe it does have the two fuel relays. To bypass one just twist the wires together?

Thanks!!

 

[MikeR351w]

I am not sure. I had a shop near town do the wiring. I think they ran a wire from under the seat and bypassed it to the relay under the hood.... Sorry I can be more help!

 

[Mustang5L5]

If you swap all the harnesses, no need to bypass anything. It's the cleanest, less problematic way to do it. A little pita, but in the long run it's a better option for future troubleshooting

 

[colorado456]

I didnt replace the harness that is under the seat with the fuel relay on it though.

Or do I not need to??

edit: I dont know if these are the relays?? They look the same lol

This is fun......lol

 

[Mustang5L5]

Topmone is wot relay

Pic in middle is fuel pump relay

 

[colorado456]

cool, thanks for the help!