Hey! So I have been working on putting a Jdm S5 Turbo into my S4 Convertible for 3 months now, and I've got pretty much everything done... except the Engine harness/Cpu connection. I have the ECU that came with the new motor, and the engine harness for it, but it's pretty much useless because I don't have the dash wiring harness to go from the ecu to the rest of the vehicle. Last week I found out that the Convertible's ECU was designed to run N/A and Turbo, but now my problem is what to do about the engine wiring harness! the S5 turbo one wont plug in (obviously), so my question is... can I use the s4 Engine harness and how do I add the turbo componants???? Or should I splice the two harnesses together to use the plugs from the s4 harness on the s5 turbo harness??? If anyone knows anything about this and can help you will be my new hero. I am the most enept person on the planet when it comes to electrical work!

 

Okay, judging by your skill in electrical work, here is what you should do in order to have the least headaches and mishaps:

1. Sell the S5 T2 harness and ECU
2. Use the N/A harness from your vert, along with a Turbo ECU. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/dumping-t2-my-n-87-a-650682/
3. Now that your car's wiring and engine wiring matches with the ECU, you will have to change some things on your engine. I hope you are good with mechanical work =)
-To retain functionality of your OMP(Oil metering pump), replace the front cover components (omp, oil pump, the cover itself, etc) with the series 4 turbo components.
-Swap out your intake manifolds for an s4 T2 so that the harness plug for the TPS plugs right in.
-You can keep the exhaust manifold and turbo, that's a good thing.

I may have forgotten some things, but basically you need to convert that engine to s4 in order for everthing to plug in. This is the easiest route if you are not good with electricals.


The easiest way ever, would be getting an s4 engine instead of an s5. But that's in the past. Good luck! I was in the same boat as you.

 

The oil pump is different on S4 and S5? I think you mistyped that one.

 

The OMP's are different on S4 and S5 engines. The S4 OMP is mechanical, whereas the S5 OMP is electrical.

Also, wouldn't he have to swap out the TB?... for that OMP lever that hooks up to the S4 TB?

 

No **** the omp is different, i never said it wasn't, i said the oil pump.

All you need to change is the front cover to use the S4 oil metering pump. Or you could just block it off and run premix and extend the life of your engine. Since he'd have to use the S4 T2 manifolds as well to use that TB(I think not sure on that one), i'm not too sure if the S4 tps will bolt onto the S5 TB though, if it will he could do that because all you need to do is make it all of the electronics S4 TII.

 

Here check this out too...

http://rotaryresurrection.com/2ndgen...o_s4_swap.html

 

Hey man, I'm sorry I read that wrong alright? Anyway, what I said pretty much went with what I was asking anyway... the TB question.

 

Don't take offense i say no **** all the time in real life, lol.

 

The S4 TB will bolt to the S5 UIM, and is necessary when using the S4 OMP.

Other than the oil pump, MaczPayne's advice is exactly right. That's by far the best way to do the swap with OEM components (i.e. without getting a standalone).

 

I am a she, actually. NOt that it makes a difference... Just thought I should set the record straight there! lol, Anyways just so you guys know I have found an automotive electrician in town that will splice the harnesses for me. It's getting done next tuesday... I'll keep ya posted. Thanks for the advice!

 

If you can repin the s5 ecu to use the s4 harness, then you are golden. That's by far the biggest hurdle.

 

To make it easier for yourself, why not get a standalone unit? its easy to install. Plus you can upgrade in the future. my .02cents

 

Did I miss something here? Why not just get an S5 turbo cluster and chassis wiring harness, pull the dash out and connect your S5 ECU engine wiring harness and chassis harnesses together? Not as much work IMHO. Maybe I'm just missing something obvious here.

 

Well, a standalone would be great, but if you are on a budget, it's hard to cough up the cash for the unit, then a harness, then all the little things plus spend the time to do it all and find help to tune it.

I am personally in the exact same boat. S5 Turbo going into an S4 N/A. I would really like to go standalone, but other than a megasquirt, they seem to all be over $1000 to get started. I would try a megasquirt, but I'm not really sure how much work is involved. I know my way around wiring, but not really the electronics part. People say a standalone is easy, but I tried searching for a writeup on how to install a standalone start to finish and I can't find someone explaining how it all works. That in itself makes me not want to do it because I don't want to jump into something that is over my head again (S5 TII into S4 NA).

I don't have the money to pay someone to install a standalone (much less know anyone around that could), so I am going to have to figure out a way to adapt the S5 ECU to the S4 dash harness. There isn't a good write-up or a good resource to show what the wires do in an S5 and the S4.

I could swap in the S4 Turbo ECU, use my NA harness, put in the S4 Turbo injectors and swap the front cover, but then that adds a good chunk of money to get that stuff and my NA harness is pretty much garbage anyway or would atleast require some time to repair it.

All-in-all if someone would take the time to adapt the S4 harnesses to work with the S5 ECU, they would be a lot of people's hero. I would definitely pay someone a chunk of cash to send me a diagram showing how to adapt one harness to the other (providing it actually worked ). It would be just so much more convenient especially with all the JDM motors arriving here.

That's just my 2 cents.

P.S. If someone wants to explain a megasquirt install or how to adapt the S4 harness to S5, let me know.

 

Hell, if you're going to spend $2000 to get your engine to work - just sell the NA and use the extra money to buy a turbo car

/sarcasm

Standalone computers are awesome, but most cost as much as an NA RX7 does. Unless you're talking about a Megasquirt, in which case you'd better be familiar with electronics and tuning yourself. A standalone computer is not a viable option for 99.999% of the world.

 

Actually, all the information is in the service manual wiring diagrams in the FAQs. I only know because I just made myself a new engine harness wire by wire from scratch. It's not the easiest thing in the world to decipher, but all the information is there. If you use that book along with either rotaryresurrection.com's or Hailers' explanation of the differences, you can do it yourself with an eyeglass screwdriver for free. Heck, I don't know why you couldn't rewire the electric OMP in to come on whenever you turn the car on by reading the wire outs and the theory of operation.