85rotarypower

I am in the middle of an engine swap right now. My 12A gave up on me and I ended up getting an '84 with an '88 engine in it. I'm having a few problems with the wiring though. There are 4 wires that I'm not sure about. They were spliced into the stock wiring harness on the 84, but I have had no luck in locating where they go on my 82. There are two 10 or 12 gauge wires that are black with a yellow stripe that are twisted together, a 14 gauge wire thats white with a blue stripe, a 14 gauge wire thats black with a blue stripe, and a 14 gauge wire thats black with a white stripe. I have had NO luck whatsoever with the wiring schematics that are in the Haynes manual I got for the engine. They are quite vague. I have also not found anyone that has documented where these wires go anywhere on the forum. Can anyone help me???????

85rotarypower

Anybody?????? Anyone who has done a TII engine swap should be able to answer this.

Feds

Hit up iluvmyrx7.com. From the sounds of it, those are power wires, either keyed or constant. If you were closer than chatham, I'd give you a hand. What's the condition of your 12a? I'm trying to get a set of 12a irons.

85rotarypower

Apex seal went on startup on the rear rotor. I believe the internals are fine since most of the apex seal is still intact. Just a small 1/8 section was missing when I took the exhaust mani off.

I'll check that out then. I've figured out two of the wires. They connect directly to the original harness. Same colour and all. Its the other 2 I don't know about. One I think is a constant power source, but the other I don't know. In the 88, it goes to the starter cut relay and the circuit opening relay, and on auto trans cars it goes to the neutral start switch (inhibitor). I tried just grounding this wire, with the 3 others hooked up the way I thought they should go, but it was still a no go. Still no spark and no injector pulse.

steve84GS TII

Gimme a couple hours,Ill look it up when I get off work.I did the S4 swap before going S5.
If your talking about the left side ECU harness that has to be integrated into the car,then most of those wires are involved with ECU power on,main power to the various solenoids(the 2 big black wires),fuel pump power/resistor,and a few other minor systems.

Ill get back to you.......

85rotarypower

Yeah, thats the wires I'm talking about. The two big black wires with yellow stripes patch into the original 12A emissions ecu along with the smaller black with white stripe. Thats the way they were on the other car. Its the white with blue striped wire and the black with blue striped wire that I don't know about.

steve84GS TII

OK,coming from the 3rd plug on the ECU
(the one that doesnt go straight to the engine)

The 2 large black wires are the primary power for the various solenoids and for the injectors.They are bigger gauge because they power several components.The ECU controls the individual grounds to turn them on/off,but the power for all of them is supplied through the 2 main wires.They should run to a 2nd gen main ECU relay under the hood,but I guess you could splice them into the FB ECU to provide the power.

White with blue stripe(3J) is the ECU constant power.Needs to go to the battery with a 7.5 amp fuse.

Black with blue stripe(3B) is the starter signal for the ECU.It needs to go to the starter solenoid and be attached to the small wire that sends the cranking signal.Its to let the ECU know when your cranking,so it can set fuel injection and retard timing.

BTW,thats from a Haynes 2nd gen RX-7 manual, page 284.I used that page when I did my S4 swap.For the S5 swap I did better with a factory manual,the wiring diagrams and flow charts in the FSM are awesome.

85rotarypower

Ok, thanks. But there is still one more wire. Its black with a white stripe. About the same gauge as the white with blue stripe wire. Is it the ECU's ground or something???

edit, the two primary power wires. Can they be hooked directly to battery power or do they have to be on a switched source?

steve84GS TII

The 2 big wires need to be switched on/off.Not only to save juice,but also so nothing gets burned out when you arent in the car.Any 2nd gen main relay will work.Its very easy to wire up and youll be able to pitch the entire 1st gen ECU then.Plus its easy to wire in a secret anti-start switch into the main relay signal wire.No way in hell the engine will start without injector and sensor power.....

Heres the S4 FSM online......
http://www.teamfc3s.org/main/factory...NG_DIAGRAM.pdf
Pages 19 and 22 are ECU wiring for turbo engines.

Go here to page 34 and look for where the black/white wire is on the plug.Then look at the description for each terminal right above the picture of the plug ......
http://www.teamfc3s.org/main/factory...TEMS_TURBO.pdf

85rotarypower

Thanks a lot. I think I can figure it out now. I have a 2nd gen haynes manual, but I had a real hard time making sence of the schematics in it. The 1st gen manual is great, easy to read, but the 2nd gen one is horribly small and hard to read.

steve84GS TII

Just out of curiosity,what terminal was that little black/white wire?

85rotarypower

The black/white wire is terminal 3A. Its a ground for the ECU. There are also 2 other grounds though, 2R and 2C.

85rotarypower

Ok, I found out that I have to hook the black/white wire to the original harness. All systems are working now, except the leading ignition. I have spark on the trailing, but no spark on the leading plugs. I think my coil is junk. I'm hoping its not the ignitor because the local junkyard wants $75 for one!! I know this because I wanted to do directfire on my 12A, but decided not to when I found out how much it was.