JDM S4 swap gone wrong
 

I need help. I have recently purchased a JDM S4 with a "cut" harness. Notice I put the word "cut". Now there are some differences with the harnesses, the harness on the motor was cut right before it gets to the intake manifold. Another on the transmission (there are alot of wires on that one), and another near the rotor housing. My problem is that I predicted (like a fool) that I cut my harness and wire the one from the motor to it. *!WRONG!* When I got the motor and the tranny in there, there were alot of differences dicovered.

First of all, there were some wires had the same colors and others that didnt match at all. My question is what wires are different between the USDM and the JDM. Do I have to run some wirirng on the other side, of the engines. My tranny and driveshaft sit about a inch shy of being flush together but it is inserted, nothing I would deem safe long term. I also have another. The brake booster vacuum location is not the same between the motors, does anyone have a clue where the exact location is? Are there any problems that you ran into? What should I do, cuz Im facing a uphill battle now. I looked all over the web for answers but I was unsuccessful, thanks for all your help everyone.

from my understanding jdm motors dont have the cold start warm up deal**where it revs up high for a little on cold starts to warm up).......and the usdm ecu has the wires for it we have 1 differance coverd

i just did a JDM swap in my 93 MX3 with a 96 KLZE - my best suggestion on the harness is to put yours back together and wire it up to the JDM engine that way - it will be more helpful in the long run - i used my old harness with the JDM and there were A LOT of differences but since the connectors are all unique at least you will get the right ones hooked up and know which ones will be left over. since the JDM didnt use an EGR, i had about 4 sensors left unplugged. now im clueless about rotary engines, but i would presume there are some similarities between JDM vs. USPEC. also, you have to remember that Japanese cars are right-hand drive, therefore things like the brake booster, clutch cylinders and so on will be on the right-hand instead of the left-hand side of the car like the USPEC. on my JDM swap i had to extend the brake booster vacuum line all the way from the right of the intake manifold to left side of the car where the brake booster is. i really hope this helps, but that harness issue is going to be a hassle without having your original harness in one piece.

I'd have to basically agree. Your gonna beat your own head in tryin to deal with that hacked up harness. Use the original and go from there.

Alot of the connectors are old and messed up so I had cut the harness at a certain spot unfortunately (the same location were they cut the harness on the JDM motor, I did keep it though). That does help that the JDM does not have the cold start or the emissions. This whole problem is based on my ignorance between the motors. I didnt find any problems on the web before the swap and assumed that there wouldnt be any. Thanks for the info and advice so far. I still need alot of help.

Well, this would be a huge PITA, but you "could" find a hart with all the pin locations, get a ton of wire, and a ton of time, and wire all the sensors individually ot the ECU. Now this would be a real bitch, but it's one good way to ensure that everything is connected securely, and you will have a nice new harness that you made yourself. I would also suggest testing all the sensors and replacing all the ones that look bad.

Not much advice, but an idea.

The brake booster feed is located on the back of the throttle body on a USA but on a JDM it's on top of the manifold near the BAC location. Looks similar to the nipple on a USA model, that feeds the Air Supply Valve.

I don't understand what your driving at when you mention the driveshaft and not mating. Is there a question there?

The wiring of cut harness is too hard to answer. I'd chunk the EM harness on the engine.

Chunk both the JDM and original if you have cut the original. Get one out of the junk yard from the same series, same type engine. Can't get one? Re splice your original one you cut in two.

The JDM EM harness is different. No cruise wires. No wiper wires. Meant for a left hand drive.

Someone probably could splice the two together, but you have to *ring out* the wiring from point to point etc. Plus there's a LOT of wires to be spliced back together. I've done this before on a engine that had it's EM harness cut at the right strut area so the wrecker could remove it. I removed the part of the EM harness attached to the car and spliced the two halves together. This was a LOT easier than splicing half of a USA to a JDM.

Ok, are the wire colors the same between the motors? Do you guys have anymore advice?

just a stupid question are you sure the jdm is a s4? as i said stupid

Yes I have confirmed that it is a s4. No question is a stupid one.

Hmm. being most or all of us have US spec cars I'd say who knows? I'd imagine that most of the wires are the same color. but what a head ach you have. Make it simple and hook up a complete un cut US harness on it and you're good to go. The FSM might have something to say about this...
good luck man