I used the search and couldnt find anything. I have a 91 CRX DX and would like to swap to 4 injectors. What do I need and does anyone have any instructions? I've read the DX-ZC topic but I got it confused with what jdmb18hatch told me. The instructions weren't the same. So any help would be great.

heres what I know I need
Si ECU
Si Distirbuter
Si intake mani
Si Injector resistor
anytihng else>
TIA
Blaze

 

thats all you need plus wire and conectors. all the wiring diagrams are the same

 

There is quite a bit of wiring.
As you know you also have to use the MPFI distributor and that has to be wired as well.
This is how to wire it all up.
I took this onfo from Hybrid Honda
The instructions are for a Dx to ZC, but it's the same as a DX to Si.

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!

 

instead of making a new topic, I'll just ask my question here. I have an 89 CRX DX and I'm going to do the dpfi-mpfi swap. Right now with my stock injection, If I'm getting into it over 3 grand I get this smell. It's not a gas smell, but it is really apparent. I also get bad gas mileage, I mean really bad. i don't even have to be driving that hard. If I drive it really easy I get good mileage. When I do the swap, will I get better gas mileage?

 

READ this! https://honda-tech.com/zerothread?id=111104

 

Sport Compact Car has a guide for this they published in an issue about 2 or 3 months ago

 

the wiring is a lot easier than it sounds, I bought an Si harness so I'd have the extra plugs and managed to wire up everything under the hood without making a single cut or splice (several cuts/splices at the ECU where it's safer) just pulling/replacing pins.

make sure you map out the vacum lines really well. It helps to have a buddy around with an Si so you can look at his.

check out my posts to see some of the other things I ran into...
https://honda-tech.com/zerothread?id=228632
https://honda-tech.com/zerothread?id=231680