Diy wiring an engine swap

[Kozworth]

This is something that I have always thought about but never physically have done. I have installed engines, Ive "swapped" from eta to m20b25, and have done a basic plug n play vw swap (ce2 mk2 from diesel to obd2 aba).

One thing that I have always wanted to kind of know is how people swap a not so plug n play engine.. or possibly non model related engines. Lets make a hypothetical scenario below.

Lets say, a 2jz into an e30 (no I am not considering this at all).

Now, the only options that I know of would be to 1). use the e30 full harness and in essence splice the pigtails of the 2jz engine components into the e30 engine harness (still utilizing full e30 fusebox, body harness etc). Issues I see here would be afm-> maf, or if a 2jz sensor had more wires then what an e30 had (such as a 4 wire o2 but having to wire in a 5 wire heated).

The other option I see would be to run a full wiring harness for the 2j along with a 2j fusebox. Then, anything that isn't engine related (such as lights, dash, radio, etc) would be cut off the 2j harness and your original e30 harness spliced essentially into a 2jz fusebox.

Besides those two, or possibly a Painlesswiring system (of which I have never researched), does it seem I have the basic jist down?

I just don't know anyone who has done wiring a swap before, and everything I read is usually just consisted of buying a 500$ PNP harness. Thanks!

[AndrewBird]

You are over complicating this. You would use the 2jz engine harness and then just hook it up where ever needed. You would really only have a few wires to splice like power and ground. The rest would already be in the harness.

Then also remove all the stock engine harness related stuff from the e30.

Things like lights and radio and stuff have nothing to do with the engine harness, so are left untouched. You could pull the engine out of an e30 and still use the radio and turn the headlights on and stuff.

[Kozworth]

You are over complicating this. You would use the 2jz engine harness and then just hook it up where ever needed. You would really only have a few wires to splice like power and ground. The rest would already be in the harness.

Then also remove all the stock engine harness related stuff from the e30.

Things like lights and radio and stuff have nothing to do with the engine harness, so are left untouched. You could pull the engine out of an e30 and still use the radio and turn the headlights on and stuff.

I understand that lights and such are not necessary. However, what I am fimilar with is vws.. In those cases, the engine harness plugs directly to the back of the fusebox.

If I had a 2j engine, the harness connector would definitely not plug into a bmw fusebox. So in that sense, either the e30 engine haress (already connected to fusebox) would have to be spliced at the engine side with 2j pig tails, or just swap the 2jz with the wiring harness to the fusebox, then splice in the tail lights and such (since it would now be a 2j fusebox)

Does that clear up what I am thinking?

[Coupelx]

Buy round c101 connector and pins, crimp onto 2jz harness, profit. You arent doing anything new so theres no need to reinvent the wheel.

dont compare vw's to a bmw. vw's are to german cars as hondas are to japanese cars.

[crash n' burn]

Way over thinking this. You have to consider the situation like this...There are multiple sub harnesses that tie together. The engine harness is a self contained entity, coorelating to the engine your using(JZ harness for JZ motor, SR20 harness for SR20 motor, etc etc). The only hook ups you'd need to do is the various power and ground hook ups for the ecu, and then for the gauges to work (rpm, water temp, etc etc).

Just grab a pin-out of the factory ecu/dash connector, and one for the engine your planning on swapping in.

Then you just start matching them up, depin/repin chassis connector to the engine harness and you should be golden.