cpubugs

I am sure this has been covered somewhere and I am just missing it. For those not familiar with my project I have a USDM 1987 RX7, I have undertaken the task of doing the ever challenging, often squimish, and seldom finished JDM S5 TII Swap. I am to the point where I am as you can see if you go to my build post where I am setting up the engine bay. So with that in mind It is time for me to decide what I am doing as far as a wiring harness.

So My main question is what do I need? Do I have an "uncut engine harness" Or has it been hacked? Do I buy a new/used one? Or can I somehow rewire the the S4? After looking at some of the pin outs this seems like a real pain. Now if I have a "uncut" harness because it is a JDM and formally RHD are there wires that need to be extended to meet the LHD.

My first instinct is to go standalone, I want a Haltech, but I would really love to see what the car has to offer stock before I go messing with it. So the Haltech will be the first upgrade. I will settle for someone pointing me to a exsisting thread, or direct responses. I will go take some pics now and post them later tonight with what I have in detail


Thanks!!!

Digi7ech

iTrader: (1)

Use S4 ECU/Harness/BAC/TPS/AFM/Boost sensor/Injectors and be done with it.

No point using the S5 electronics.

cpubugs

I appreciate your enthusiasm but to me that seems to me to be more of a work around and If the S4 electronics where better, I really find it hard to believe that Mazda wasted money on research and development to create the S5 if the S4 was just as good.

Anyway, Thanks again.

Digi7ech

iTrader: (1)

S4 and S5 don't mesh.

S5 ecu has limp mode all over it if your missing a single thing.

Then the interior harness will have to be repinned to mate to the S5 ECU and harness.

On top of that ,you'll be missing one of the FEM interior plugs if you use the S5 Jspec harness.

I have done many conversion harnesses and I drive a converted car daily.
My first engine swap was a S5 block. It's MUCH easier to use all S4 electronics on a S4 car.
Using s NA harness you only have to mess with 3 pins and then extend a few things like BAC wires.
Even using a S4 TII harness would be easier.

If you want to use the S5 injectors and BAC then you'll be better off scalping the plugs and wiring them onto a S4 harness.

cpubugs

Thanks again, but I am not looking for easier. I am looking for right. I know that sounds stubborn but the goal is a S5 Jspec t2 conversion, not S4.

toplessFC3Sman

iTrader: (1)

break out the soldering iron and S4 and S5 FSM's then. I dont find wiring to be too much of a big deal, but many people do.

The way I'd attack it would be to use the S4 harness as a base for as much as you can, only changing the connectors to fit the ones on the engine or ECU based off of comparing the FSM's. This way, just about everything will reach properly for a LHD car and a lot of the misc. stuff like the wipers, cruise control, warning lights etc will stay in the same spot on the connectors between the emissions and front harness.

Dont forget that you will need the S5 TII AFM and pressure sensor, among other odds and ends. Your S4 stuff wont work regardless of if its NA or TII

cpubugs

S5 TII AFM and pressure sensor- Where are they?

Would they not have come with my swap? It has everything on the engine and attached to the harness. I think.

Wiring doesn't scare me, so I am pretty sure I will end up doing something along these lines.


I had a few qestions like the ports and plugs I marked on the pictures some things I have plugs and no where to plug them into. And some have ports with no plugs to fit. The two on the ECU and the one off the harness are my main concerns.

Time to print the FSM.... lol

cpubugs

The fact that this is a JSPEC motor does it change what I am looking at in the FSM is there a jspec FSM in english? What is the black attachment on the side of the ECU? And the 3rd plug circled in teal or whatever color I picked, what does it go to? Just looking for a non wiring diagram answer. So I know what I am looking at on the FSM.

Digi7ech

iTrader: (1)

Jspec ECU's are basically the same as US.

No clue what the black plug is. Most likely not needed.

The two smaller yellow ones are part of the EFI harness.
The other is the interior harness.

The red circled plug is either FEM01/FEM02 // x15/x16 (S4 same terms/do a search for those) Your missing one of them(jspec harnesses suck).

I didn't do a whole lot of mapping of those plugs but your idiot lights go through there/Wipers/Temp GaugeCruise control. Some of the others are power/grounds.

THe Blue circled one on the ECU is Plug 3 which has all the power/injectors lines.

I can't be certain on the blue circled plug. You'd have to say where it came from. It almost looks like it's the 2nd plug for the ECU while the green one iof the interior harness plug 1. Not sure though.

cpubugs

Looks like I may be selling my truck and buying my Haltech... This just seems like more trouble than it's worth.. Not that I don't want to learn but I just think I will have more flexibility...

yeah the two yellow ones are for plug one and two on the ecu the green and blue circles.. If plug three on the ECU is interior stuff it would make sense then as to why I do not have a plug that goes to it. Now the fun stuff begins... Have to go get a fuse from my multimeter..

Alex6969

Don't Jspec ECUs have a built in governor? Whereas the American versions have none.

Icemark

actually the S5 body and electronic changes were mostly done to cut costs... the majority of the changes didn't improve the car. The S5 electronics are cheaper and less accurate (the water temp sensor a classic example).

Delphince

It happens that I just purchased most of the things for this exact swap (91 bt into an 88 N/A) today. I have the engine and entire powertrain to the rear, and both series 4 and 5 harnesses, but not the ecu. I'm having a little trouble summing up all the different ideas suggested in this thread into a single course of action. What are you guys suggesting is the smoothest method to make the connection between harness and ecu and what series for each without sacrificing performance? Wouldn't the s4 and s5 ecus have slightly different mappings since the motors have different turbos and compression ratios? Once I get started on the dirty work, I can't spare the time to have the car off the road for more than a couple days of solid dedication.

Delphince

For instance, would it be simplest just to dismantle the dash and install a us-spec S5 interior harness, ECU, cluster, and engine harness on the j-spec engine? Or are there interior mismatches?

Icemark

almost nothing matches from a S4 body to a S5 electrically and you are trying to do the worst of all conversions (series change).

You would be better off taking a S4 engine harness (tweaked to a turbo), and S4 front engine cover and S4 OMP and putting it into your S4 car with a S4 Turbo ECU... or build a custom harness, or use an aftermarket ECU.