Is there anyone out there who has erformed their own WRX into RS swap and can give us aspiring swapper some insight. Myself, like some, do not have the money to pay for a shop to complete the swap for me and I need some info. What is the best way to tackle the wiring of the new harness. What issues are there with installing a WRX fuel pump, or a Walbro? Any help would be great guys!!!

don't take this the wrong way, but it's adressed in almost every thread in this particular forum.

Since you're so close to Lachute Subaru (http://www.lachutesubaru.com), talk to Mark about doing your swap. Less headaches in the long run if you're like me and don't know yer way around a soldering iron. :p

I've spent some seat time in their handy work and it's sooooooo nice. :D

-mykr.

We like souldering irons :)

Mark

yeah, you're looking at 12+ hrs of souldering FUN!

I'm not afraid of a little soulder....:eek:

ps.

Mark...I've been meaning to call you, I just need to finish exams!!

Originally posted by Scoobed
don't take this the wrong way, but it's adressed in almost every thread in this particular forum.

I have never seen detailed information on converting the wiring harness here or anywhere else. Everyone just says match up the stock harness to the WRX one and solder... Well ok yeah that is the general idea, but what we need is detailed info on which wires go where. I have the wiring diagrams from both cars, but it isn't very obvious how the 2 harnesses should be combined. If anyone has detailed info on this PLEASE share it.

slim - I don't think that shops like I-Speed or Lachute really want to give away their "secrets" when it comes to a step by step to doing the swap. They've invested ALOT of time, money, sweat and tears into perfecting techniques and I think it's fair for them and others like them to keep these methods to themselves to put food on the table.

Also, wiring looms can change at a whim with auto manufacturers. I know this first hand dealing with Ford Motor and their MCR (Material Cost Reduction) programs. I'd assume that Subaru follows a similar practice of trying to cut costs and stay competitive.

Just my 0.02 (adjusted for my honourary Canadian citizenship. :lol: )

-mykr.

Oh I am well aware companies doing swaps would never give out this kind of information. Nor would I expect them too, they have way to much time invested in that knowledge. However what I was hoping for was that someone who has done the swap themselves would be nice enough to put together this information to help out others. Anyone feel up to it?

Again, each car is individual so providing the step by step wiring will apply to only a very select few cars.

The basic procedure you are going to use is as follows:

Locate the non-engine related wires existing on the car and seperate them from the engine related wires. Locate those same wires on the WRX harness. Now you "simply" add in the WRX engine related wires to the existing non-engine related harness and voila. Then you have all your CEL's pulled and spend the next two months retracing everything trying to find where that missing ground is or those two crossed wires.

Unfortunately, I have not done this yet but I am looking to do it in July. Yet unfortunately again, it will be of little help to you since I will be putting this into a 96 L wagon, not an RS.

-Jon

Ok so I'm thinking I don't have to mess with any wires other than the ones coming out of the ECU, is that correct? The 2002 WRX has 122 wires out of the ECU, rough estimate is that less the half are engine related. Are these the only wires that need to be matched up and combined with the RS harness? It seems like their should be more than this as people talk about 12 hours worth of soldering time. So what am i missing?

It looks to me like it's the front wiring harness and the bulkhead wiring harness that are going to be the focus of the hacking. I'm sure it's not as modular as it appears, but the FSM makes it look like you just need to use the entire WRX engine wiring harness without anything from the older car. I can't find the WRX ECU pinouts right now, but I think most of those were directly engine related.

I think a lot of the 12 hours is not just soldering but achieving the factory look so it doesn't look like a big hack job.

-Jon

Nice to see everyone voicing their oppinions. THANKS GUYS

Perhaps some of the veteran Do It Yourselfers could point out some trouble spots and or things to watch out for when wiring??

We all know that hindsight is 20/20 :cool:

Just a question that has been bothering me...

Why do you want to use the stock RS ECU and not use the stock WRX ECU? (assuming RS ---> WRX conversion) It seems that the RS ECU would limit the redline to 6250RPMS.

Who said anything about using a RS ECU for a WRX swap? You can't, the redline is the least of the issues, it has no concept of boost or fuel maps for a turbo. It either won't work at all or it would blow the motor. Some people use an aftermarket ECU like the link, but most people use the stock ECU from the model of WRX the engine came from.

Originally posted by slim speedy
Who said anything about using a RS ECU for a WRX swap? You can't, the redline is the least of the issues, it has no concept of boost or fuel maps for a turbo. It either won't work at all or it would blow the motor. Some people use an aftermarket ECU like the link, but most people use the stock ECU from the model of WRX the engine came from.

Ahh, the boost and fuel issue was also brought up in one conversation. If the engine and ECU are from the same car, why is there such a problem with wiring? Is it from all the accessories (lights, dash, wipers, etc)?

Well, from what I know the problem is with splicing the WRX harness and RS harness together. You need to use the WRX ecu, obviously, and you don't want to rewire the whole car, thus grafting the wires from the WRX ecu to the part of the RS harness that feeds the wires in the cabin would be the pain?? Correct me if I have this all messed up!!!

It is "easier" to utilize the existing wires in the car and just adapt it to the new engine and ecu versus removing the entire harness and putting in the new harness from another car.

-Jon

Is it to expensive to create a new custom harness that's sold seperately? I saw a bunch for Honda's when do their various swaps. I know they're two different animals, but the concept is still the same. Then people could do the swap themselves and the tuners make loot from the custom harness. I don't think harness should be cheap either, like around $500+. Just a thought since I have a plug in play harness for my link.

This has been discussed all over the place. Subarus cannot have pre-made harnesses done like Hondas because Subaru chose to change wiring at almost every MY and sometimes more than once during the MY. Since there are already very very few Subarus that might do this swap, there is really no feasible way to mass produce these harnesses. Most of the companies will tell you that they need the car there to ensure an exact harness.

-Jon

Re: not wanting to pay someone to do your swap, you might want to look and see what your time's worth.

Can anyone here estimate how many hours they spent performing an engine swap? Is it 50 hours? 100? 200?

If the time spent is nearly the same amount of time it would take you to earn the $$$ to pay a reputable shop to perform the swap, I think you'd be better off paying a shop, since you know they'll either do it right or fix the mistakes for free. And the shop will probably get your car finished quicker too.

That's just my take on it, I haven't performed any swaps, but I've seen a few go bad...


-s-

I don't know about the other people here, but I mostly want to do it myself because I like working on my own car. It would be a nice feeling to be able to tell someone you did the work yourself when they ask. Unfortunantly I will most likely have to pay someone to do mine, as I doubt I will have a garage I can use for long enough to do the swap myself. I have pulled off a turbo install, new radiator, and suspensions installs in the parking lot outside my house, but a WRX engine swap might be a bit much.

What are you talking about? Mine is going to happen right outside the front door of my apartment. :D

Of course, I'm shooting for having the engine swapped over and the wiring done in about a week's time.

-Jon

I'd have to agree with Slim, some of us like that fact that we did some of the work on our cars ourselves. Alot of us also don't have the money to pay someone to do the work. I wouldn't mind working with someone on how to do this, and post on a site. Maybe a make a VFAQ on the swap. Trully I don't think that these shops that do the swap are going to lose any business because we post "The Secret". I even bet we can come up with an adapter for the swap that'll even save the shops time and money. Anyone have any suggestions?

Maybe I can help answer this question having installed 2.2, 2.5, 3.3 and 2.0 turbos into Vanagons.
The wires that need to be integrated into the Main wiring harness are for the following:

Battery power
Ignition power
Speed sensor
Check engine light
Tach signal
Fan relay 1
Fan relay 2
Fuel tank pressure sender
Fuel tank valves (2 or 3)
Fuel level
Fuel temp
Oil pressure
Coolant temp
A/C system
Transmission (if automatic)
Rear defogger
Light switch
Neutral switch
Starter
Fuel pump

Other than these wires, the connections needed from the new harness are connectors that go to the engine, ECU, O2 sensors, diagnostic connectors, fuel pump controller, and the air flow sensor.
I may have missed some connection in this list since I'm working from memory but this gives you a starting place. Simple eh.

I'm feeling generous today so here's a few important tips:

Be meticulous and label every wire you cut. Label it with at least the pin location number or better if you have a description of what the wire is.

Study the wiring diagrams for both cars and write down which pin location is the wire for what and try to match them up to the corresponding pin location on the new ECU.

Cut the wires so they are staggered. That way, when you clean up, there is less of a bulge in once place. Soldering and wrapping will make your wire thicker and you don't want all the thick wires in one place.

Study the differences between the wiring between your Impreza and the WRX. For example, the fuel pump relay is grounded by the ECU on the RS whereas on the WRX, it is grounded on the body. Make a note of the differences.

Make sure you look closely at the numbers of all harnesses, relays and connectors. The diagrams may have the same 4 wires listed but have them listed as 1, 2, 3, 4 and 3, 4, 2, 1.

Best thing to do it braid together the wires first and then go through and solder them all. Then wrap them in electrical tape.

Follow the diagrams closely for wire colors. Just because a wire is a certain color in the engine bay doesn't mean it'll be the same color after it enters the firewall.

I'm sure I have things I haven't covered but these are the more important stuff that remains prominant in my mind.

nizz

Thanks smallcar and nizz. Both of those posts are very helpful.

-Jon

Is there any splicing that can't be done by simply matching the coresponding pins on the two ECU and splicing the appropriate wires?? I haven't gotten my MY02 WRX bulkhead harness yet :(

Thanks guys

where did you get your bulkhead harness from? i'm looking, but i may end up going jdm anyway.

I AGREE THAT INFORMATION HAS BEEN HELPFUL FOR SOON I TOO WILL BE TRYING TO GET MY HANDS ON A EJ20T.THE THING IS I JUST BOUGHT A 95 IMPREZA L BUT WILL NEED HELP ON WIRING.I OWNED A FEW HONDAS(<---BE EASY ON ME) AND HAVE DONE SOME SWAPS WITH SOME BUDDYS OF MINE.BUT ILL ADMIT THAT THE MECHANICALS WONT BE TO BAD BUT THE WIRING WILL BE A LITTLE MUCH SINCE I AM NEW TO SCOOBYS(ALWAYS LOVED THEM!)AND HAVENT HAD ANY EXPIRENCE WITH THEM.I WISH THERE WAS A MANUAL OR SOMETHING OF ALL THE WIRING DIAGRAMS I COULD LOOK AT AND STUDY.:cool: WELL JUST TO LET YOU HUYS KNOW THIS FORUM IS DEFINETLY THE BEST FORUM IVE BEEN(NEWB)TO.

If you have the actual connections, you should be able to use the wiring diagrams to get everything together. It would just be better to reference the harness and the diagrams to have two points of reference.

Boost4U, no I don't have access to another BWH; sorry.

-Jon

Wow, this thread REALLY encourages me to go ahead with my swap now:eek:. Anyway, since we're all talking about swapping in a wrx ej20t what do you all think is the best route for me and my 96 legacy 2.2?
I've read a lot of different opions, everything from swapping the entire car harness over to just using the ecu. I'm thinking since my car is an automatic 2.2 as of now i might be ahead to put in the wrx harness. What do you guys think?
My goal is to swap in 02 wrx 2.0 and the 5mt that came with it. I would also like to use the wrx guages as well to have wrx bling (and a proper redline/speedometer etc.. ;) ). I have the entire wrx harness too (unfortunately it's from a wagon and my car is a sedan).
Hopefully i'm not butting in on the guy's original post as this is somewhat different :banana:
Brent

My strategy is going to be to lay out both harnesses and keep any wires that will continue to be used; ie: non-engine related. Those wires that will be needed from the WRX harness will be merged into my current harness to replace the unused wires from the previous engine.

In your case, serious, it may be beneficial to you to pull both harnesses and then start with the WRX harness and merge in any wires that are NOT engine related. Basically, the direct opposite of what I am shooting for.

I dunno, it could go either way.

-Jon

sorry if this is going off topic, but would using an aftermarket ECU simplify this process. Would you still need to splice all the wires, or just connectors?

Anthony C

Depends on what aftermarket ecu you went with. Some are wire in and some just plug in. Others plug in and have a complete wire harness for the engine included.
What is available all depends on your car. For me and my legacy they are all pretty much wire in. So to answer you question, yeah, it might be a little eaiser to just go out and buy a plug and play if you could. Even if you had to wire it in you would still have instruction which would be nice!
Brent

Or you can hunt around for a cheap Unichip harness with the plugs to plug into the ecu... and whatever wires you have that can be used from the original ECu and whatever that isn't included you can wire your own.


Not hard and alot cheaper than a bulkhead harness.

http://www.flat4turbo.com/gc8/DSC01382.JPG

Imprezd~

p.s. you will possibly have to swap a few things sensor wise but not too bad. Will probably finish sometime this weekend will give an update as well.

what motor are you swapping in? and how many wires approximately need to be wired into the ecu plug?

USDm will let you know when i am done.

what we need to do is post which wires need to be spliced from the RS harness. thats assuming you're swapping into an RS.

I am going to start a new thread with the pinouts and we can go through and figure things out. I thought it might become a sticky so that's why I will start a new one.

Cool. As soon as i finish this summer school class next week i'm going to start on the wrx side of my harness. I really need the wiring diagram for a MY00 RS or at least the pinouts. Lets start a thread dude, i think this is a lot easier than people are making it seem, it just takes time to do it initially.

It is easy the hard part is seperating the harness and staying interested in doing it...

That's why i am doing it my own way i guess... I am actually behind schedule as well.. so my notes won't be ready as of yet...

Imprezd~

oh yeah, where'd you get the connectors for the engine side of the harness?

My motor came with them..

LOL, what a small world. My final summer class ends this Saturday. My drivetrain arrives Monday or Tuesday. Project starts that night... Once we all get going we should definitely pool our resources and get this wiring figured out.

I haven't decided if it is best to do all the mechanicals first and then do the wiring or do the wiring and then the mechanicals.

spiralsmurf, PM me.

-Jon

as you can see the motor is in my car and has been in for a while I just haven't been able to devote time to the harness. My WRX takes priority lol.

It's fairly simple the first thing you want to do is sort out what you don't need to use in wrx harness and what you do need.

then you will want to loom as much of the wires that go to the same direction together.

You will end up with alot of wires... but what i have found works is that you cut and separate the wires that have crazy routes and make then as clean as as siimple as possible.

Try and weed out as much of the non engine related wires as possible.

Once you have both cars ecu diagrams and it should be a simple cut a tap situation since they alot of common sensors. Some are not so common too though.

I'd be up for a stick on how to do this long as the information is good. I'll be doing my conversion in a 96 legacy so it will be somewhat different from the RS's but should have the same idea. I think if we all had a good point to start at then this entire wirring project wouldn't be so intimadating.
Brent

stimpy, i'm with you. lets get the info out there. puckaveli already posted started a thread and as soon as i start my wiring i'll be contributing. also there are a few compability issues related to power steering, a/c, oil pump, and those types of things. we need to get a list of what works with what and what doesn't.