The 5.0 in my 86 has had it.
I have a 5.8 from a 90 that I would like to swap in. Will the 5.8 plug into my 86 harness?
I compared the ECM wiring diagrams between the 86 and 90 and they are very similar. Most of the pin numbers match up between the two, but the 90 has a few that aren't on the 86.
These are missing from the 86 diagram
#4 - ignition suppression resistor
#31 - Can purge solenoid
#17 - To ML IND (not sure what this is)
#21 - idle air bypass valve
#48 - STI test connector
#40 - oxygen sensor
#6 and #20 - ground
For the most part the wire colors are even the same between the two. Although I did notice the oxygen sensor seems to be wired different.( has 2 wires from the ECM on the 90 and only 1 on the 86).
So far I have only really looked at the wiring diagrams. Tomorrow I will dig a little deeper to see if the 5.8 will even physically plug into the 86 harness.
Just looking for some feedback from anyone with experience in this area.
thanks

 

http://www.fordfuelinjection.com/truckpinouts.html
Did some more searching, this chart doesn't really match the wiring diagrams in my Chilton manuals though.
According to this chart it looks like it would run if all I did was plug the 5.8 engine into the 86 harness and change the ECM to a 5.8.
Is an EGR solenoid and EVP the same thing?

 

you will want to use the 90 5.8 harness and 90 5.8 computer. the 85-86 harness years where different then 87+ and the 5.8 wasnt efi till 88. you can try using your 86 setup but be prepared if things arent working right to try the different harness. that website you posted is the place to refer. remember the injectors stay in the same order as they where on the 5.0, just the plug wires need to match the 5.8 firing order.

what tranny do you have in that 86? if its an AOD you will need to get a specific flexplate. do not use the 5.0 flexplate or the 5.8 flexplate as it was probably bolted to either a C6 or e4od.

you need an 88-89 crown victoria 5.8/aod flexplate these run about $60 new and is the only way to go. you will also want to get the y pipe from a bronco/f150 that had a 5.8 in it since the 5.0 is to narrow and wont bolt up.

 

The tranny is a zf 5 speed from an f-350. This was the tranny that came with 5.8 so I still have the proper flywheel for it.
I also have the 5.8 harness if I need it.
If I use the 5.8 harness, at some point it will have to be joined up with the chassis wiring in the 86 or are they totally separate harnesses?

 

totally seperat which makes it pretty easy. the harness just plugs into the firewall, where the ecu goes. or from the website just make the 86 harness match the 90 ecu.

good combo you got there. the zf is an awesome tranny

 

Yeah the 5.8/ZF is a nice combo you'll like that. FWIW my '90 doesn't have a canister purge solenid.. maybe the HD trucks are different or maybe the Chiltons diagrams are wrong.. who knows. #17 ML indicator is the check engine light.

 

The '90 engine harness is not the same stand-alone deal that was used in 87-88. The best bet would be to use the 86 engine harness with the 90 computer, adding in the circuits that are missing and moving any that use a different pin location in the computer plug.

The EGR solenoid is the EVR...the EVP is the EGR valve position sensor.

 

It doesn't look like the 5.8 will physically plug into the 86 harness.
I don't really know enough about automotive wiring to attempt to cut and splice harnesses.
I'm looking into a wiring harness from fordfuelinjection.com.
They have a 5.0 universal harness that claims to be able to install a 5.0/5.8 into a vehicle.
http://rjminjectiontech.com/?p=4

 

I have the exact same swap except my 5.8 is a '91 and AOD. The 5.0 EEC harness will hook right up, mines been in, running and passing SoCal smog for 10 years. It runs just fine around town and empty, only real problem is it falls on it's face real bad trying to tow anything at speed. I towed my VW Thing back to the Desert on an open 2 axle trailer last week and had my foot on the floor for 5 hours on flat freeway, admittedly I was running 70mph. Took 19.6 gals of gas from Phoenix to Yuma (180 miles). I usually get 12.5 mpg running empty but once in a while it will surprise me and pop out a little over 15.
Also, the harness from a newer truck won't work, the EEC is under the dash in '86 and the '87 and up is under the driver side kick panel.
I think I'm gonna break down and rewire the EEC plug with the missing BS and plug in the EEC I have laying around from an '89 Bronco 5.8.

JohnF

 

so your running the 86 harness and 5.0 computer on that 5.8? if so you need to get that changed as the efi tables are way different and more then likely the cause for that motor falling on its face. I also wouldnt tow in OD with that AOD. the 85-86 AOD are prone to failure and the OD bands are not meant to tow period.

 

UPDATE;

I installed the EEC from a '89 Bronco with a C6 tranny. I added in only the VSS+- wiring and it seems to be working just fine. It has an EGR and a fuel pump code and I haven't traced that down yet. The EGR might be just a slight difference in sensors. I know the fuel pump code is because I didn't add that circuit to the EEC. There are a couple circuits not required for 87-89 EEC if your GVW is under 8500 lbs (as I remember) and even the VSS, according to some people, is only needed if you have an electronic tranny. I have an AOD but I had already hooked the VSS up before I read that.

I haven't towed or gone any real distance since the install but my son says it's running fine and was getting 17MPG mostly freeway running.
I plan on taking it to Yuma this next weekend...we'll see how it does.

JohnF

 

So your 86 harness plugged into the 90"s engine?

 

The 5.0 and 5.8 engines are identical from a wiring harness point of view.. all sensors and actuators are in the same locatons with the same connectors. I have had both a 5.0 and 5.8 in my '90 and didn't need to make any changes to the harness for it.

 

Yes.
The 86 harness is missing a couple circuits relative to the '87-up EEC as I mentioned. The only thing I had to cobble a little was the thermactor system. I mixed parts from the '86 and the '91 engines and it all worked OK and passed smog. I don't know what will happen as far as smog goes with the newer EEC installed. The '86 has no emissions light in the dash so the codes aren't noticeable unless they actually checked the system with a code reader...which they don't on anything older than '96 and newer with OBD-II.

JohnF