TTrotary7

iTrader: (5)

hey,

So quick intro and I will try not to bore everyone with too much detail, a while back I bought a roller shell of a 93 FD, touring model. no interior to speak of, no engine, no transmission, good body, straight frame super cheap.

Along the way I have purchased a many parts from fellow forum users, (thanks you all who have helped me piece this thing back together) so now I have a full interior, mainly composed of new parts, new carpet, and the seats will be re-uphosltered soon, to complete the interior part. ( I will be doing a build thread at some point)

Anyway, I secured one of the brand new Mazda 0 mile motors from Ray Crowe (along with many other parts) and was going to try and piece it together from scratch (not sure it was a good idea) so I ran across a great deal on a JDM engine, trans, ECU, harnesses, and all. Compression tested at 118 in the front rotor and 110 in the rear rotor, I tested again when the engine arrived to make sure and sure enough it checked out.

So the engine seems to be in good shape, but I'm not going to let a brand new motor sit, so I started moving the parts over to the new one. everything is going smoothly until I realize a couple of things:

1 - This motor is super clean, all parts are in really good shape, kind of different from what I constantly hear about JDM motors
2 - I see the black box that replaced the rats nets, so this thing has to be a 96+ so I dig further and find out its actually a 99+ 280ps spec engine (N3G1) so I say "Cool!" I got a good deal!!

Then when I go to test fit the ECU in the car, I realize the dash harness does not fit in the ECU (should be obvious different year model cars). and so at this point I say Sh@#$ and come to the only place one should come when trying to figure out issues with their FD, RX7club.

After extensive searching and reading, this seems to be a thing that happens to people like me, who thought they bought a 93-95 engine and get a series 7/8 motor instead and have to deal with the wiring harness.... there is even an extensive thread by NightWalker86 on this exact thing, and seems he is trucking along with his solution.

So here is where I stand, I already have a USDM engine harness, so I could swap it out the JDM one no problem, from what I understand you have to pull the plugs from the JDM harness and get them onto the US harness so the black box works as it should. then after that get a power FC and it should just plug and go.

I was also thinking, would the power FC (FD3S4) be able to run the black box instead of the rats nest? (don't know)

Here is my preferred method, I get a 99+ dash harness and swap that out. I unfortunately have pulled my dash more times than I like to admit, so I can have the thing out in 10 minutes flat so pulling the dash to replace the harness is no big deal. But can I even get a 99+ dash harness anywhere? and is that all I need?

Suggestions are welcome, I'm not sure if a series 8 Power FC will plug into a 93 dash harness... I would guess not, would any other aftermarket ECU work? I can keep the JDM harness and use that if another ECU plugs into both. I don't have any 93 engine parts that I can swap into this thing so I'm stuck with the 99 spec one. looking for the best/easiest path forward which to me is to swap out the dash harness, unless a super smart guy here has a better way to go about it... thanks in advance for the help!

arghx

iTrader: (3)

Soo... forget about the engine. Do you have all the other harnesses you need for the Car interior? Buying a jdm engine didn't make a whole lot of sense when you have a brand new one from Mazda and what you really need are USDM parts to make it work.

Why don't you make this a stripped out race car instead of devoting your life to undoing what someone else did.

and power FC is a good choice for drop in mild modded applications. You might as well get something that requires rewiring the car, either an engine swap or a Haltech or something.

the real solution here is to sell everything and go LSx with a nice kit. And you know I love rotaries, but you're in over your head trying to take a roller and make it like a car that was never stripped out. Leave the basket case cars to swaps, and sell the good parts to people whose cars aren't so far gone.

TTrotary7

iTrader: (5)

Thanks for the input, the car is already back together, the interior is but a couple of pieces away from being finished (dash vent and glove box). So it's not that far away.

all the wiring is there, all the harnesses everything. I'm simply needing to hookup a dash harness to the ECU, don't see going to the extreme of putting a LS1 engine in because of one wiring harness...

i didnt have any motor parts to begin with, thus why the JDM motor comes in the picture, to take off all the parts and move them over. Worst case scenario I can ditch the rats nest and twins for a single setup and use a 93 power FC.

no offense but if I wanted a corvette I would have bought one, or if I wanted a race car I would have also bought one, I wanted to restore the car as a project, and I'm literally one harness away from doing so, don't want to hack up the car with a sily LS1 engine, but thanks for the suggestion.

arghx

iTrader: (3)

Buy a new USDM harness from ray crowe.
Keep the 99 turbos and sell almost everything else or go single and get USDM parts.

trying to mix and match 99 spec right hand drive 16 bit ecu parts and wiring with a us car is a big nightmare.

TTrotary7

iTrader: (5)

So I already have the USDM harness, could grab a power FC, at that point it's a matter of the rats nest working on the US harness.

i could just buy a rats nest off a 93, not sure if that would work though.

cr-rex

iTrader: (114)

the only incompatible parts you have is the black box and the jdm harness. switching to a 99 dash harness isnt all that simple. the dash, engine and front harness are all attached to each other. so if you replace one, then you have to replace the other 2. the only situation that doesnt apply is when going from AT to MT...... as far as i know.

to get your stuff to work, either delete the rats nest and use the usdm harness and s4 power fc OR get a rats nest and use the usdm harness and s4 power fc. either way, the black box, 99 harness and ecu wont be used. also keep in mind the 99+ were rhd. trying to use a harness from it could pose some problems as it wont be as easy as flipping the harness the other way. a lot of the plugs and everything else wont reach everything.

youre on the right path with what your doing. you certainly CAN over complicate this but it would be better not to. just use the usdm harness and the power fc and you can be on your way. you can deal with the rats nest later so long as your vacuum lines are correct. finding a 93 rats nest shouldnt be all that difficult really. people scrap them all the time.

TTrotary7

iTrader: (5)

i didn't think you could just "delete" the rats nest, I can certainly use the USDM harness, and get a S4 power FC. If there is a way to lose the rats nest I can try, though I've only read it being "simplified" or removed for a single conversion.

j9fd3s

iTrader: (3)

i've done this before, and here are the bits of info that you need to make up your mind.

1. the new engine you bought is 99 spec, so that part is the same, no worries there.

2. the 96+ black box works exactly the same as the 92-95 setup, except its simpler.

3. the 99+ ecu, if you got it, is WAY WAY WAY better than the stock 92-95 ecu.

4. the 99 engine harness does fit the LHD car.

5. obviously the 4th connector on the ECU is different for 99+, although the pinout for both has been posted, so its actually simple to adapt the US harness to the 99+ ecu, its about 10 wires.


so basically the choice is to run the 92-95 solenoids/wiring/ecu (pfc) or the 99+ solenoids/turbos/ecu, stock is quite good, for a PFC you'd need the 99+ one.

if it was my car i'd run the 99+ stuff, its a huge improvement.

TTrotary7

iTrader: (5)

Also, wouldn't the 99 UIM and LIM be different and not plug into the USDM harness? I also could just be making stuff up at this point....

j9fd3s

iTrader: (3)

6. all the sensors/injectors and coils are all the same 92-2003

TTrotary7

iTrader: (5)

Thanks for the info, I would also like to keep the 99 stuff, something about going back a decade in technology seems wrong to me... but if one must then one must. I do have the 99 ECU.

so let me see if I understand you correctly, I would just need to re-pin the 4th connector (dash) to fit the 99+ ECU correct?

j9fd3s

iTrader: (3)

sort of, the actual plastic connector is a different design, so you need to make a little adaptor to go from the US connector style to the 99+ JDM connector style

if you need to source the connector, HKS has Fcon harnii and this may work (it looks ok, but they seem to not know Rx7 fitment) 1JZ Soarer 4-row ECU Connector - Wiring Specialties

TTrotary7

iTrader: (5)

what if I swapped out the harness for the USDM one, ditched the rats nest all together and go non sequential with a power FC? I think that might work as well

dguy

iTrader: (8)

I'm not trying to start another PFC shitfest but if you're going to all the trouble and not keeping the stock functionality why not just pitch the factory harness and use a real stand alone?

TTrotary7

iTrader: (5)

what is your suggestion? The overwhelming majority of posts on this forum recommend a PFC thus the reason I'm thinking of going with it.

cr-rex

iTrader: (114)

yes yes yes... you 100% can. the rats nest is an necessary set of garbage. people utilize it for various personal reasons but by no means is it required. single or twin, it makes no difference. you can delete it.

same as what j9fd3s said, the motors and sensors and everything are all the same from all the years. the only real difference is the rats nest becoming the black box and the later models have no oil pressure sensor. its plugged from the factory since the gauge was replaced with a boost gauge in the cluster.

this.... do this.... 100000% do this. forget everything else and do this. it will be the most simple your engine bay can be short of going single. youll have 3-5 vacuum line TOTAL and youll just love life a whole lot better. troubleshooting becomes childs play, working in the engine bay becomes as simple as working on a 90s honda, EVERYTHING becomes accessible. its a dream, really it is. the simplification alone is reason enough to do it. youll love the responsiveness of the non sequential set up as well. having instant boost from as low as 3000rpm is magical. everything is just better non sequential.

to touch on what else was mentioned, it seems as though you can use your 99 stuff with some fidgeting of the wiring if you so chose. if thats something you want to do then go for it. its really just more work. if you want to go the simpler path and use your usdm harness and use the power fc then go for that too. just keep in mind if you use a stock ecu, youll need to have a stock set up for it work properly. the advantage of the power fc is that you can pretty much do what you want and it offers you the ability to have your set up tuned. yea the stock ecu will be just fine, but who would prefer a stock ecu over a properly tuned stand alone on the same set up?

my recommendation is do some research on seq vs non seq set ups and go from there. its kind of the gateway drug to making the decision on everything else youve asked about....

TTrotary7

iTrader: (5)

Thanks man, I really appreciate all the help, as always this forum delivers in community help and people willing to just answer questions. Going non sequential with the USDM harness and ditching this whole rats nest. Will get it in my build thread once I get some time to write it

dguy

iTrader: (8)

If it were me it'd be:

Street - Haltech

Race - Motec

TTrotary7

iTrader: (5)

I'll do some research on the Haltech, I presume you use this setup? what makes it better than the Power FC?

dguy

iTrader: (8)

I've rigged a few cars with them and am currently building my street FD with an elite 2500. I'd use it on the street over a PFC because it speaks CAN and is almost infinitely more flexible with regards to inputs/outputs, and is actively being updated. I wouldn't touch their older platinum ECUs with a 10 foot pole personally.

Its a harder initial setup but in my opinion its an easier, and more rewarding end goal.

TTrotary7

iTrader: (5)

Though an interesting setup, it doesn't solve the issue at hand. even if I got a Elite 2500 with the Series 7/8 adapter for plug and play, I'd still be out of luck for connecting the dash plugs... unless they made me a whole new harness.

If I am going down the same road of ditching the rats nest and going non sequential, I don't see twice the money advantages for the Haltech. if there was a clear superiority worth the extra cash, I wouldn't hesitate to do it.

I am also not going to mod this thing out to oblivion, so though a ton of extra features are available in the Haltech, I'm not sure I would use any of them.

I'm don't have a ton of info on the Haltech though, so if you have some data that shows it is a clear cut better choice, I'd be more than willing to study it.

dguy

iTrader: (8)

I was suggesting moving to a different ECU and pitching the plug and play aspect. If that's not your bag I understand. With regards to features etc you may not use them but troubleshooting and fine tuning with more well rounded ECUs is far easier in my opinion.

Also the 2500 is certainly overkill, Haltech (and others) have way more affordable options available if you're not going to do anything fancy.

DaleClark

iTrader: (55)

OK, here's the deal.

If it were me, I'd use -

- New engine (core short block)
- JDM upper/lower intake manifolds (they have no AWS or EGR)
- 93-95 US wiring harness
- 93-95 US rat's nest with all the emissions solenoids removed
- Block off ACV, remove double throttle
- Run JDM injectors, coil packs, sensors, etc.
- PowerFC for the 93-95 cars (FD3S4)
- 99 twins that came with JDM motor

You'd have a nice platform there for 300-350 HP, easy to drive, easy to troubleshoot, good to go.

Running the "black box" is a neat idea until you realize it also has all the emissions solenoids in it. Much easier to pick and choose solenoids with the earlier setup. And, if you break off a plastic vacuum nipple, have fun tracking another black box down. 93-95, just get a handful of good solenoids.

Haltech is a great ECU, but unless you NEED what it can do it's a lot of money. You can easily go $2000 into a Haltech. If you're making a dedicated track car, big power single turbo car, etc. it makes a lot of sense, lots of flexibility, failsafes, more inputs/outputs. For a street car on the twins, it's total overkill.

If you do need emissions, there's a whole 'nuther ball of wax. Non-California you'll need the ACV, the solenoids that go to it, airpump, main cat, and airpump plumbing. Pass all day long with a PowerFC. California is a whole nother thing entirely, I won't get in to that.

Dale

TTrotary7

iTrader: (5)

I'm in the track you just laid out, though I'm thinking of just ditching the rats next all together and do non seq. With the PFC.

USDM harness, everything else gets transplanted. Don't need emissions in the city I'm in, so I should be good. Good info on the ECUs though agreed the haltech is overkill for me

TTrotary7

iTrader: (5)

Bringing back and old thread to life... so I just finished putting the engine in, US harness, into a US car by the way.

There are several “extra” connectors on the engine harness to the car, i looked around in the passenger side but didn’t see any places to connect... anyone know where all of those extra connectiors go?