I have a 89 CRX DX.

I really want to convert it to mpfi and was wondering if I can just use a HF or SI engine bay harness with out any modes to the harness. Did anyone do that before? Tight budget here. Don't wanna waste my money on buying a SI or hf harness for not thing. Thanks in advance.

 

To my knowledge you can not use the full si harness. You will need to do a mpfi conversion. here is a good write up.

http://www.fourthgenhatch.net/mpfi.html

 

While I was looking around on here for this exact kind of info. I read up on the Web-page you listed.. I cant seem to find any info to explain more about the injector resistor box, I am currently doing a d15b swap on my 91 DX. Dpfi-Mpfi, being I will be running a vtec and obd-1 computer box. Will i need the injector box or not? kinda stumped here. It also is confusing me with the wireing, according to the diagram given it is say that the #1 main injector on the DP will be #3 injector on the MP? And Im guessing the 2 AUX injectors on the DP are #1 and #2 for the MP? Sorry guys kinda lost on this wireing. Thanks in advance for any help.

 

with the OBD1 injectors, you don't use the injector resistor box - as for the injector wiring, on the DPFI chassis harness you have a yellow wire at ECU pin A1 and a yellow wire at ECU pin A3 - these yellow wires connect together inside the harness and become one yellow wire which runs to the DPFI auxiliary injector - you have a red wire at ECU pin A5 and a red wire at ECU pin A7 - these red wires connect together inside the harness and become one red wire which runs to the main DPFI injector - in order to get 4 wires from the ECU to the 4 MPFI injectors, you need to cut the existing yellow wire at A3 and cut the red wire at A7 and connect 2 new wires (one to each) to the portion connected to the ECU and run them out to the engine (leave the cut wires that remain in the harness not connected to anything) - A1 controls injector #1, A3 controls injector #2, A5 controls injector #3 and A7 controls injector #4 - you take the 4 yellow with black stripe wires from each of the 4 MPFI injectors and the 2 yellow with black stripe wires that ran to the 2 DPFI injectors and connect them all together - see the attached PDF for DX to D16Z6 wiring (D15B will be the same)

 

IGN HOT-->resistor box-->4 wires to injectors-->colored wires from injectors to ecu

edit: err late post

should have 12-14ohms across each injector circuit total, results will vary depending on what type of injector you are running

 

Ok thanks man.. Just at a guess the 4 yellow/black wires are goin to be a ground or a relay. 4 yellow/black wires = 1 to each injector.. Well guess ill grab a Coke-a-Cola n rip this old motor out for the new d15b. Thanks man.

 

This should be stickied due to people winding up with a DX out of dumb luck. Biggest problem with a DX is this dual-point injection...

 

the 4 yellow/black wire from the injectors are for power - they connect to the 2 yellow/black from the DPFI injectors, which is also power - the yellow/black originate at the main relay as one wire and splits into 2 wires inside the harness - actually, you only need to connect 1 of the yellow/black from the DPFI injectors as they are both the same - if you just connect one, make sure you tape up the other real well so it can't short out on anything - it is "hot"

 

Correct - just to clarify even further, the YEL/BLK wires are +12V switched, NOT grounds!

 

Aha! Now I understand it.. The yellow/black wire is hot and runs as a constant power supply while the 2nd wire to each injector is used kinda like a toggle switch, to sorta flip a breaker and allow fuel to go through when needed... Wiring these little cars seemed difficult but is becoming easier. Well thank you for your help. Thank god someone knows what to do!

 

damn.