J-Spec-Boost

k guys i know this has been asked before on here and i have read through alot of it but im still really confused so here is the plan.. about 4 months ago i bought a 87 N/A and i have stripped it right down in order to rebuild it and drop in a turbo motor. I have decided to stick with a s4 motor but go with a j spec one and get it iver race ported or bridgeported. But i am confused on what is the best set up? if i was to use the N/A wire harness what ecu do i use?N/A or can i get a turbo ecu to work on a N/A harness and how hard would it be to use the j-spec harness and ecu? and plus i would like to use trek7 on my ecu so i have to stick to the s4 motor! please and thank u in advance

KompressorLOgic

iTrader: (6)

you want the t2 ecu, the na ecu wont run the engine right and u will blow your motor!

so u need the t2 long block. and an american rx-7 t2 ecu, boost sensor and afm, throttle cable... t2 hood probably...

i would not recomend using the jdm harness its quite different. you can use the na harrness, if you dont connect any of the emissions components. and lengthen the tps wires a few inches, and the BAC wires around a ft or so..

id recomend the rtek 1.7 and a pair of 720cc secondary injectors, and a walbro 255 fuel pump or at least a t2 pump.

J-Spec-Boost

can i just use a american t2 harness on the j spec engine and the american t2 ecu

KompressorLOgic

iTrader: (6)

yes u can.... however thersa driverside engine harness and a passengerside engine harness....

most people dont get the driverside t2 harness...

you will have to modifiy a few wires on the t2 pass side harness to use it with a usa na driverside harness...

otherwise you wont have any temp gauge, and there wont be a plug for the alternator.

basicly between na and t2 the alternator and temp gauge plug switch harnesses... so with a na driver and t2 pasenger u end up not having those plugs at all!!

J-Spec-Boost

well dont it make sence just to get boths sides of the t2 harness

KompressorLOgic

iTrader: (6)

yeah it would. but this one runs undr the dash so its a bitch to change.. thats why ive seen alot of people not use it...

bugman1973

i did a swap from a carbed motor to an s4 engine and had to change both sides aslong as you can remove the old one you can route the new harness almost were you want it to go aslong as things hook up right so its not as hard as it could be.

LeeTheSlacker

you need to cut a few wires and you can use your na harness with the tii stuff just fine. i would know, i did it.

no need to **** with the other side.

J-Spec-Boost

well i bought the car after someone had lost interest in it so the person before me just cut the harness at the fire wall so i have to replace it anyway... so both side's of the s4 turbo harness i think is the way to go?

HAILERS

The other SIDE to the EM harness, is the FRONT harness. The Front harness runs from the passengers side to the dirvers side, exits the drivers side and goes fwd up to the very front of the car to the relays there etc.

Plus it must then also mate with the real ENGINE harness which is on the left side of the car. And then I'll make honarable mention of how the Front harness interfaces with the cluster harness and leave it there.

Ooops. I forgot. The Turbo Engine harness has the two alternator wires so you'll also need to get it with the other two turbo harnesses. The Engine harness has the plugs for the cas, alternator, oil pressure sensor, battery cable wires etc.

Now let me see. Do I want to strip all the harnesses out of the car and replace them with ones out of another car. Or do I want to extend two BAC wires, two AWS (Air Bypass Solenoid) wires, maybe, and address whether I want a knock box or not? and do it that way.

Or buy a Turbo EM harness with no alternator wires plus different pin outs for the two plugs on the EM harness that mate with the Front harness (about six wires that won't mate b/t the two plugs right) and do it that way?

And I know not what ECU you have, but I THINK they only use N332 and N333 series four ECU's and not the peculiar JSPEC ECU.

Then again, if you have the time and the engine bay is open with no engine......maybe changing all the harnesses out isn't that difficult. Still have the run across from the passengers side to the drivers side to deal with. Old plastic parts crack is something to remember.

That's as far as I care to go with this thread. Done.

KompressorLOgic

iTrader: (6)

yeah just use the passengerside t2 engine harness. and use the na driverside one. i

ts a crapload of work to change the driver side harness... and you only need to modify 3 wires to use the pass side t2 harness anyway... save you many hours.

HAILERS

Not really. You need to use the stock non turbo EM harness for ease of simplicity. Only a couple of wire adjustments. Use the Turbo EM harness and you have a few more wiring adjustments. More tedious/difficult/tiresome.

Here's a jpg of the two plugs that the EM harness mates with the Front harness with. Everywhere you see the ( ) with letters inbetween, is a wire that is peculiar to the Turbo car and each of those wires SHOULD be addressed if you install a Turbo EM harness to a non turbo Front harness. At the minimum at least thought about for a few minutes and consider what they do in life and what happens if you don't *take care of business*.

If you keep all non turbo, then you don't have those wires to fool with. Plus the Tubo EM harness does not have the two altenator plug wires in it.

Don't pay any attention to the words written on the jpg. They were for another thing/thread.

J-Spec-Boost

ok guys everyone seems to do this swap different so here is my situation.. the person who owned the car before me cut the harness's right at the point where they exit the firewall into the engine bay on both sides, then removed the ecu so i no longer have the N/A ecu, also i no longer have a N/A complete harness so i need to work out what harness i need to find? know i am able to get my hands on the entire north american s4 turbo car harness, thats everything from front to back and the s4 turbo ecu but is that going to work with the j spec engine?because in theory i should be able just to plug the north american s4 turbo harness in all the sockets on the j spec engine then run it into the engine bay on both sides and plug it in to what i have left of the N/A harness for the tail light,exc and then plug in the s4 turbo ecu.