I have got a 1991 f150, 2 wheel drive reg cab that I bought with a wrecked 5.0l engine. I found a wrecked 1990 ext cab 4x4 with a good running 5.8L engine, and have got that engine now all installed into the 1991. I used the 5.0 harness( seems to be the same)but kept the vacumn lines from the 5.8 with it, along with all the sensors that were on the 5.8 or directly conected to it. I'm wondering if there's anything else I have to change or do to make this swap work, I've heard someone say I might have to change the computer? Is there anything else I should be changing? Any help would be greatly appreaciated, Pete.

 

Noone seemed to know this one, so I ended up calling ford on the matter. The mech there told me that yes I should change the computer with the motor. Said that the paramaters might be different between the 2 computers, and the one from the 302 might work on the 351 and it might not. Anotherwords, yes, change the computer, it's found behind the emergency brake pedal, take off the platic kick panel and there it is. One 8mm bolt holds the comp in and another under the hood buried nicely under the brake booster and cruise components holds the plug into the computer. Theres also a rubber boot on the computer that fits into the firewall, very tight, and what worked for me was to put that rubber onto the computer, then on the outside of that rubber spread a little motor oil and it fits back into place with little effort.

 

Yep, computer should be changed. The harness is exactly the same. You shouldn't have to switch engine harnesses to use the 5.0 harness/sensors. Just drop the 5.8 in and plug in the engine harness to the truck harness. Just beware that the 5.8l may have had an E40D and the computer might be programmed for it since it is electronic. If it did, this could still cause issues.

Some differences between 5.0 and 5.8:
Distributor, accessory mounts, intake, fuel rail, exauhst manifolds or collector height, computer.

The swap is very easy if you have a complete 5.8.

 

Thanx spaceman for the reply, I did change the computer and it runs alot better now, it didn't seem to run that hot with the 5.0L computer so I didn't drive it, for fear I would wreck something. The swap did go good, everything bolted up nice, not so easy working outside on gravel.......but it did work. You were saying about the E4OD maybe causing trouble? I think both trucks have the same tranny, they both got a "E" on the door tag, and they are both electronic od trannys. If this is ok then please let me know, you have either done this before or you're a ford mechanic, cause all the differences between the trucks were just as you said. Thanks again, Pete.