qcoffey

I know, I know. I did a search already and couldnt find the answers I was looking for. I have an '88 DX Hatch in which I am installing an '89 Si engine and tranny.

My question is I have the complete Si harness installed on the engine going in, can I use this harness instead of using the DX harness? All the plugs plug in , except for the fact that the Si harness has an extra square pllug with six wires in it.

I would rather use the Si harness because it plugs directly into the resistor box. Any help would be greatly appreciated.

Spaceballsthelunchbox

No no no no.
you didn't search right.
You CANNOT use the Si harnes on your DX car.
Unless, you go through the trouble of replacing the entire car wiring harness.

you MUST use the DX engine harness and convert that harness to MPFI.
Do some more searching, try DX to ZC which is the same wiring job.

Here These are the instructions I used a very long time ago.
I got this from hybrid Honda.
follow this and you'll be set.

4G DX to ZC wiring conversion
by kenji
In order to convert your dual point injection DX to multi-point injection you will need 4 injector plugs, an injector resistor box, extra wire, a wire stripper/cutter, heatshrink and/or electrical tape, and some patience. Also, when doing this conversion I would highly recommend soldering all connections and heatshrinking them. If you do not have access to heatshrink neatly wrapped electrical tape will do just fine. It is also extremely helpful to have an extra multi-point injection engine harness laying around to take plugs from (i.e. injector plugs, injector resistor box plug, and distributor plug). Listed below is a straightforward and easy to follow set of instructions to help you complete your DX to ZC swap:
DX to ZC

Inside car @ ECU

· Pins B10 and B12 are empty. Unused pins can be taken from B2 or B11. Some models have a wire located at B12.

· Cut orange and white wires off at C1 and C2 and connect them to wires added at B10 and B12. Orange-B10. White-B12. Leave enough wire for next step.

· Run wires from C1 and C2 (direct ECU connection) into the engine compartment. Label these wires for later use.

· Cut wires at A3 and A7 leaving plenty of wire. Run these wires into the engine compartment and label them for later use.



Outside car

· Transfer DX wiring harness over to ZC engine.

· TPS and EACV plugs are too short and must be extended.

· Be sure to switch green/white and yellow/white wires on TPS



Injectors and injector resistor box

· Connect the yellow/black wires from the two DX injector harnesses and run it to the yellow/black wire on the injector resistor box.

· Connect the yellow wire from the DX injector to the #1 injector (brown wire).

· Connect the red wire from the DX injector and run it to the #3 injector (blue wire).

· Connect the A3 wire to the #2 injector (red wire).

· Connect the A7 wire to the #4 injector (yellow wire).

· Connect the 4 red/black wires from injector resistor box to each injector.



Cylinder position sensor

· Connect C1 to blue/green wire on cylinder position sensor plug.

· Connect C2 to blue/yellow wire on cylinder position sensor plug.

Thats it. Double check everything and start it up. Good luck!

RuthlessEF-9

yeah what that guy said ^

qcoffey

Thanks for the advice. I just finished my wiring about an hour ago. At about 4pm est, I looked at both harnesses closely and noticed that the wiring colors were diffierent. At this point I said forget it and went to work using the exact same set of instructions you provided off the Hybrid Honda page. All I have left to do is pin the ECU and see if it starts. I'll keep you posted.

qcoffey

I got some good news. After finishing my wiring harness and changing the oil, I attempted to start my vehicle. It started on the first try. Unfortunately it wouldn't rev past 3000 rpm. I couldn't figure out the problem. Finally I decided the problem was in the distributor I was using.

I was using the stock dizzy like a dummy. I did this because the plugs were different and I couldn't plug in the Si dizzy. Finally I decided to swap connectors and wire in the correct one. After doing so the car ran perfectly.

Thanks to those that gave me good advice along the way. All I have to do now is swap the DX knuckles for Si ones and I'll be good.