Buninskies

OK so I had my 85 rx7 gs for a few months now and its my first car and me and my dad got ahold of a 13b rew with the trans. The problem is we have to find 2 major parts. The ecu and the wiring harness. And I checked eBay and there are ECU's but the only thing is that they are all JDM and I'm pretty sure my engine is USDM (I think thats the correct term) and the question I have is: Will a JDM ecu work on a USDM engine?

atheadwins

iTrader: (3)

Looks like a fun project, have you checked the classifieds section on here? Surely someone will be selling an ECU and Harness.

Buninskies

Ah okay thanks I'll be sure to check that out

DreamInRotary

iTrader: (49)

Yeah, I'd check around on the forum here for a part out and source yourself an ECU and wiring harness.

I'm not sure on the JDM vs USDM ECU comparison, but I'd just try and find someone here who's selling their stock ECU. There's plenty of them floating around the 3rd Gen Classified section that you shouldn't have a problem finding one.

Good luck in the swap, I'm going to be doing another one here soon as well!

Buninskies

Alright I plan on swapping it later this year because of money, so i got time, and good luck to you too on the swap.

craaaazzy

iTrader: (9)

i have an ecu from my motor if u'd like it. i'll get you the ecu number in a few.

Buninskies

yea sure I'll get back to u by 3:00 when u get the number (I'm in Illinois btw) bc that's when I get back home from school

craaaazzy

iTrader: (9)

ok, i have a '94 automatic ecu so not sure if that'll work for u. u may want to do some research but let me know if interested.

here's some info i found via quick google:
'93
N3A1 - Fed MT
N3A2 - Fed AT
N3A3 (ends in 881A) - Cali MT
N3A4 (ends in 881A) - Cali AT

'94
N3C1 - Fed MT
N3C2 - Fed AT
N3A3 (ends in 881B) - Cali MT
N3A4 (ends in 881C) - Cali MT

'95
N3D8 - Fed MT
N3D9 - Fed AT
N3E1 - Cali MT
N3E2 - Cali AT

Buninskies

OK I'll do that.

craaaazzy

iTrader: (9)

oh, i also have an extra engine harness (it may be from the automatic motor as well but u can make it work if ur good at wiring) that i no longer need. i know the CAS plugs are broken off of it (pins are still on the wire though) but depending on which front cover u use, u may need to modify those 4 wires anyway. btw, the engine harness only has 2 of the 4 plugs to go to the ecu so u'll need to source the other 2 plugs.

Jeff20B

iTrader: (13)

You might consider reworking/rethinking the complete FD setup to ditch the clunky (heavy) stock twin turbos and go with a better more efficient aftermarket single turbo like a lot of the FD guys do. Another reason is the stock twins don't fit with a stock 1st gen radiator as the lower hose is totally in the way of the front turbo and the two wastegate spring housings. Been there, done that.

Your front cover should also be changed to a 1st gen version because otherwise you'll need to fab up some new motor mounts to mount under the rear iron. But why reinvent the wheel? Been there, done that.

I think you can substitue an FC CAS in a 1st gen front cover and have it work with the stock FD ECU instead of the front cover mounted FD CAS modules. j9fd3s mentioned something about this recently. But of course I wouldn't want to stick with the stock FD ECU anyway.

You also need a GSL-SE oil pan. No other pan will fit with the stock main crossmember. And any other option requires some re-engineering.

I guess I'm wondering how dedicated you really are.

Jeff20B

iTrader: (13)

In one of my "been there done that" references, this post by PercentSevenC has info on how we did his FD install in a 1st gen and the problems we had. You'll see what I'm talking about regarding the radiator vs stock twins. https://www.rx7club.com/nw-rx-7-foru.../#post11192106

By the way he kept the 1st gen tranny. Why swap to an ill-fitting FD trans? Heck even a T2 trans will fit better than an FD trans with only a bit of work and you won't need to worry about the lame pull style clutch the FDs had. There is plenty of info about T2 trans into 1st gen swaps.

Here is a link https://www.rx7club.com/1st-gen-non-.../#post11833198 to the other "been there done that" which has to do with the stock FD motor mounts and what the previous owner did to make them "work" in a 1st gen. It is a flawed concept because it takes a lot of weight off of the trans mount, which it wasn't designed for, and the stock FD motor mounts are liquid filled and very soft as they were designed to work with the FD's power plant frame which is fairly rigid and traverses the end of the trans to the front of the diff, connecting the two and adding stiffness or helping in some way. Without the PPF, you could grab the upper manifold and easily rock the engine left to right. Terrible end result and would have driven really crapily. I'm glad he never got it up and running. Because it allowed me to get the car when he gave up on it.

Dysfnctnl85

iTrader: (11)

I really wish there was a better resource and as a developer I would love to put something together. For instance, many build threads have dead links, dead pics, or less-than-concrete information.

When I'm not working on my own never-ending project, I'm thinking about how to put together a guide with a nod to how software is documented (https://readthedocs.org).

Yes, there are a million ways to do it. There's not even a 'best way' considering time, budget, etc., so let's document all the ones we (the community) know about!

For instance, today, I needed to know with certainty the heater hose to use for connecting the firewall heater nipple to the coolant inlet on the side plate of my 13b-RE. Since my car was a 12a, I have literally no idea which hose will work. I've ordered the hose that works for earlier 12a's and the 13b models because I don't have a beehive oil cooler. I certainly hope it works.

I'm also not quite sure why my s4 alternator doesn't fit my s4 water pump housing without washers on either side of the saddle mount. There's apparently a mythical spacer that I can't seem to find in any post, in parts fiche, etc. I've stacked washers on both sides and my pulleys seem to line up now. ::crosses fingers::

Little things like this are maddening. Maybe they are totally intuitive to some people, but not to me.

Maybe it's a lost cause!

craaaazzy

iTrader: (9)

i had to go non-sequential when putting my motor in as the large actuator will hit the front subframe. and when going non-sequential, u can remove the bottom turbo precontrol actuator as well if u weld the flap open...this "may" give u more room for the outlet of the stock radiator. but when doing this, u'll need to upgrade to as aftermarket ecu (i'll be using a PFC myself).

if u do decide to use the stock ecu, you'll definitely need to custom fabricate the mounting to use the REW mounting set up.

Jeff20B

iTrader: (13)

Dysfnctnl85, a new heater core hose should work fine on an FD rear iron. You need to pull the weird plastic extender off. You'll see the steel tube with ridge that the plastic thing clips to. You can use this steel ridge as a nipple/barb to clamp the hose on to. At least I think that's how we did it on Percent's car. We also reused his old beehive hose which was long enough, but not very supple and new anymore. Whatever we did seemed to work.

Your alt issue is weird. I've never had to add washers on either side like that. Sounds like your alt pulley sticks out way further than it should or maybe it's not an actual rotary alt. At most I've only had to swap pullies and/or spacers (the small one that sits behind the pulley and came in several lengths from 8mm to 10mm more or less).

As for making a big list to make things easier in the future, well, I've never needed anything like that. Maybe it is simply intuitive for me to just sort of "know" which parts work together, but I did have access to lots of unmolested stock parts. I don't think youll have much luck making a big list when you don't have several known stock OEM examples to reference. Maybe just go with the weird washers until you have more info. As long as the belt is aligned properly, it's not going to wear prematurely. Just go with it until a proper mythical spacer and pulley with a small spacer are available.

Oh and I've never installed a T2 tranny in anything before so I couldn't tell you all that's involved.

notveryhappyjack

iTrader: (4)

spot on Jeff. one other note is the custom drive shaft required

follow Jeff's advice, the wiring will be a challenge either way with a FC or FD swap in FB. Consider a standalone ecu if your going to the effort to re do the wires.

Banzai-Racing

iTrader: (11)

We always have at least one (right now 2) either 13B-RE, -REW or TII FB conversion going on in the shop.

This may help you figure out what you are about to get into.

Cosmo RE single turbo Banzai Racing (Sanders 13B-RE Cosmo Conversion & Engine Installation)

13B-REW single turbo Banzai Racing (Walker RX-7 Engine Installation)

Buninskies

Oh hey banzaii is here too! Um yea I have at thinking about having my engine sent to you guys to have it rebuilt and checked.

j9fd3s

iTrader: (3)

the short answer is yes, you need to cut the same 4 wires as the Apexi PFC people.

the long answer is still yes, but its longer. maybe that should be an affirmative?

anyways the JDM ecu ditches the AWS, EGR, and E/L unit of the US car. the E/L unit is a bit of a magic box, there apparently is nobody in the world that knows how it works, i've asked a few times. both the JDM and the US ecu's get inputs for electrical loads, like the lights, and defroster, etc. the JDM ecu just has a pin for each one. the US ecu ran out of pins, because Mazda added the EGR, and AWS, so they send all the electrical loads to the E/L unit, and then that goes to 1 pin on the ecu. (it also does the tach, and the CEL).

happily the JDM ecu is the simpler one, as US ecu is the weird one.

the JDM ecu also will not drive a check engine light, it does spit out codes though, you need to hook an LED up to the diagnostic port, so that means you need a diagnostic port. the JDM ecu will drive an exhaust overheat light, so if you need the cel to light up when you have the key on you can use that pin.

i have a JDM FD ecu in my FC, it was a big job to make it happy in the car.

Buninskies

OK cool I'll keep that in mind