RXntrik7

I'm planning on using my flashed ecu and TII motor from my 87 TII in my new 88 AE. Will the harness in 88 fit ecu and motor from 87?

RotaryRocket88

iTrader: (7)

If your '87 is a late year-model, there will be no difference at all between the two harnesses. If it's an early '87, it will use a resistor pack and low impedance injectors. '87.5-'88 used high impedance injectors and no pack.

RXntrik7

Im pretty sure it was early 87 TII that I pulled the engine and ecu from. Can I tell if the injectors are high or low just by looking at them. If so could I just splice the low impedence injector plugs into 88 harness and use my 87 ecu and low impedence injectors on my 88 ae?

dawicka2

Yes.. that way makes the most sense.

Use na harness (just extend tps wires) and splice in resistor packs..

The swap is pretty much plug and play.

HAILERS quote "Using t2 harness in nonturbo car makes no sense imho"

john ny

RotaryRocket88

iTrader: (7)

Just leave the wiring alone completely. Remove the UIM and unplug everything, then leave the whole harness in the car. Swap the fuel injectors between engines, put the new engine in, and plug everything back in.

It's actually going from one turbo car to another, so no need to mess with any of the wiring.

RXntrik7

That's not a na harness, 88 is a turbo. But I guess you're right, that makes most sense if I wanted to keep the 720 secondaries and rtek 1.7 that are on the 87 motor. Is resistor pack on na cars same as on TII? Reason is cause I would probably have to fish one out from a junkyard, cause I don't have my old TII anymore to get one from. Also where is resistor pack spliced in into the harness?

Sorry if I make all this sound confusing, but I'm not a guru in rx-7 wiring and I don't wanna fry anything.

RotaryRocket88

iTrader: (7)

^ Seriously.

RXntrik7

Would you feel safe runnin that rb turboback if you didn't have rtek?

RotaryRocket88

iTrader: (7)

The only concern you should have running a full exhaust system is with your wastegate. If it's not ported, an open exhaust will create boost creep that can blow your engine. Especially the S4 wastegate. It's so tiny.

RXntrik7

I do have a ported wastegate on a s5 turbo and I would still get boost spikes up to like 12-13 psi. Fortunatelly rtek 1.7 corrects timing after 9 psi. Anyway you re right I'll just get my high impedence injectors rebuilt and leave the harness and all in place. I'll try not to pop the motor on those 550's

RotaryRocket88

iTrader: (7)

Wait, wait. I didn't notice you said you're running an rtek 1.7 & 720cc secondaries. You HAVE to keep the secondaries properly sized, or the engine will blow the first time you go into boost. You can't use 550cc secondaries with the 1.7. With this in mind, swapping to the '87 harness and low imp. primary injectors may be the easier route after all. You can get away with no wiring if you do this.

Alternately, if you leave the high imp. harness in the car, you'll need to wire in 2 resistors for the low imp. 720cc secondaries (or 4 if you choose to re-use your '87's low imp primaries). You don't really have the cut the low imp. pig tails off the '87 harness either. You can use something like an exacto knife or razor blade to trim the plug to fit the low imp. injectors. It's just the tab offset that differs.

RXntrik7

That's what I wanted to accomplish from the getgo. Could you be more specific on the whole resistor splice in procedure?

RotaryRocket88

iTrader: (7)

Yeah, it's very simple. 6-10 ohm, 10-20 watt resistors are soldered into the injector wires at the ECU plug. The wires are:

Front primary: LG - Pin 3E
Rear primary: LG/B - Pin 3C
Front secondary: LG/W - Pin 3H
Rear secondary: LG/R - Pin 3F

Take a look in the FSM fuel and emissions section for a diagram of each wire position on the plug side. Cut, splice, done.