Need help!! I put a 10/95 351 OBD2 motor with wiring harness in a 04/95 OBD1 truck that had a 302 in it. Plugged in the wiring harness off motor into the same harness that was in the truck. now it won't start seems to have fire but injectors don't seem to be working. A guy at the part store told me I needed to repin a few wires where the harness's connected. Sounds good but this is the part where I would like to ask for help before messing something up! And having broke something then asking for help.

 

What computer are you using? There are a few differences with batch firing injectors or sequential firing injecters. Firing order of the motor is different as well.

Adrianspeeder

 

The firing order should be the same 351 firing order for both engines. Both engines have a roller cam. My 1995 F150 5.0 with OBD 1 has the same firing order as my 1992 Mustang 5.0 HO. Both are Mass Air.

Do you still have the original harness?

 

The "engine" probably isn't the issue.
The EFI system, sensor array and powertrain wiring harness absolutely must match whatever processor you are using. Mixing and matching might be possible but it's not likely to be straightforward.

Also what tranny was behind the 302? The 4R70W and E4OD have very different pinouts.

 

YES I do still have the original harness on the 302 motor. is that what i should start reconnecting on the 351? and thank you for responding some people say its possible and some people say its not.. I think it is I Just need help and thank you again

 

Which processor are you using?
Do you have them both?
What transmission do you have?
Was the 302 MAF or S/D?

These all determine what you can or cannot do.

 

thank you for responding... It has the E40D in it with the OBD1 harness in it all the way up to the engine harness that is the 351 harness.. but still have the 302 engine harness.

 

Put the 302 harness on it and see what it does. The harness should work fine. The issue I see is the computer will be looking for responses that are 302 based, the 351 will use more fuel and have more power and that may confuse the computer. With computer controlled transmissions, the Ford computers look at specific engine RPM to tell the transmission when to start shifting. It takes like a full second to complete the shift and when you have more power, the engine can rev beyond the normal specs before the tranny shifts.

I changed the rear gears in my truck from 3.08 to 3.55. Now when I hold it to the floor, the engine winds and winds before it shifts. I usually just pump the pedal once to get it to shift sooner.

 

Did you figure out away to make your truck run with the obd2 motor? If so how , and how did your Trans react?
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