i am looking for help so any comments or criticism would be appreciated. i have a 90 crx dx and will be swapping a b18a in the next month. i am not a big wiring enthusiast though i can do it. to make long story short i think i might have found a way to make the thw wiring relatively simple by running 3 wires instead of the 4 that are usually called for. under the normal way of doing things it would also require you to rewire the mpfi harnes as well. my way would allow you to use a stock harness. i am going to skip over the wiring for the cylinder sensor as i didn't see a way around it and go to fuel injection.

after looking at hasports wiring charts and a couple of wiring diagrams, i figured there was no sense in running the two wires for the fuel injectors being that they are already there. the four wires for the dpfi use pins a1, a3, a5 and a7 just like mpfi. so really just plugging those wires into the proper position for the injectors would be all that is needed. next i thought the resistor pack has to have ecu controlled power and that brought me to the next question. where does it draw it's power from in a stock mpfi setup. i found that the power comes from pins a13 and a15 (ign power for ecu) both these wires are yellow w/ black stripe running into the main relay (the resistor pack got its power before it went into the main relay). mpfi systems in the 90-91 integra and 88-91 civic/crx's are ran this way. so all the conversion would really need is to run a yellow wire from these wires to the resister pack and it should work.

has anyone ever noticed this or looked into it? any reasons as to why it wouldn't work?

 

well i am going to post some info also

as u were saying.... why 4 cables for injectors.?? if u have done MPFI conversion (wich i have) u will notice that A1 and A3 along with A5 and A7 conects from 4 to 2 cables.... each pair a few inches off the ecu conect into a single cable straight to the main and the secondary injector.... all u gotta do is splice the 4 cables individually and run it to the designated injector on MPFI...
as for the inj resistor.... yes.....the yel/blk cable its a pos voltage cable... its the same cable as the fuel pump, as in the main re=lay, and the ecu...
thats one of the reasons if the main relay goes bad ur fuel injection, ecu and fuel pump wont work..... theres just the same cable runnign around for simplification purposes....
also u gotta rewire the distribuitor, and thats another 4 cables u gotta repin
theh crank angle sensor and the CYL sensor.... thats another cables u forgot to mention and that doesnt make MPFI a 3 cable process...
basically all u do its to ur stock harness.. but adding 2 cables for CYL sensor on dizzy, 2 cables to injectors....

 

thanks for clearing that up. i already knew about the cylinder sensor wiring and crank angle sensor, i just didn't want to go into it taking more space than needed. my diagram was a little misleading so i do see what you said. i guess 4 wires is a necessity.