88-91 dual-point Conversion BREAKTHROUGH

hello,

I posted a while back and asked about using a 88-91 si harness on a b16a1 with the hasport subharness on a 90 4dr dual-point. Some people replied that you cannot use the si harness, they said it will not work and u should always modify the dual-point.

Well....

I think it is easier to use the si harness with the hasport to wire the engine out of the car so u dont have to modify any of the engine harness or add wires for the resistor box or injectors on the engine side. All u have to do is use your old dx connector and re-pin the si wires into the dx connector on the resistor box side. Then u need a body-side harness connector for the 6 wire plug on the passanger side. Then you can just run all your wires directly to the ecu ( 4 new injector wires, ignighter coil, etc.) In the end, the swap is much cleaner as the engine harness is NOT modified at all. Let me know what u think, I just finished the swap and we have no codes and it is running great. Very clean engine bay as well. Contact me if you need help.

oh yeah i had a question about mpfi swap. I think someone said that if i use obd1 injectors that i wont have to have a resistor box? Because my friend is selling me a VX intake manifold with everything for $10. It will plug right in right? I mean it will work when i do the regular wiring without a resistor box right?

well a vx intake manifold is like a HX civic or HF crx. Fuel economy. The manifold and throttle body are smmmmmmalllllllllllllllllll!!!!!!!! You dont want that. All of the sensors, injectors and crap are good. But IMO the manifold isnt worth anything besides taking the TPS sensor and other stuff off of.

Don't use a VX manifold. Everything else sure, but the VX manifold is small. I refer to that manifold (and the 5th gen CX manifold) as a pea-shooter. You'd be better off with any of the other ones than those 2.

yeah but the work you went through sounded alot harder than modifying your car for mpfi with a dx harness. and with the dx harness, i switched back to dpfi in like 5 mintues. i wonder how long it takes to switch back to dpfi with your setup

1. Im just doing the swap so i dont have to later, because when i get a new engine itll have a new manifold.
2. why would you switch back to dpfi civickiller?

nobody answered my question lol, do i need the resistor box? and does it wire in the same as an si manifold?

i had to switch back to dpfi because my b series motor was blown when i got it so i had to go back to my 1.5 dpfi.

you dont need a resistor box when running obd1 injectors. you take the power wire from you current injectors or the biggest yellow wire in the drivers side strut connector and then run 4 wires from each injector to the drivers side strut harness and tie it in with the power wire

even though i have obd1 injectors im probably gonna be obd0 still, i still wouldnt need a resistor box right? heres a pic of my manifold, i picked it up a few hours ago.

http://files.automotiveforums.com/gallery/watermark.php?file=/503/140601intake_manifold.jpg

yup if yoru still obd0 but running obd1 injectors, you still dont need the resistor box. the signal sent to the injectors by the ecu is all the same, its just a matter of powering them right that varies between cars

oh ok thats cool, thanks man. I hope my friend has the TB tomorrow so that its complete, i just need a dizzy, and a computer now. SHould i get an si wiring harness or do i not need it? Honestly i know nothing about wiring. I can follow directions though. lol

do you have the injector harness for the obd1 injectors ?

dizzy plugs arent really needed, just for cosmetic looks. and to make it look cleaner for hte wires you need to run from the ecu.

this has been done before...i actually posted about it. I did it for my car....it is a much cleaner look. But, it is a whole lot easier to add 4 wires than to repin the whole engine harness....you'd need the diagrams (which i've made myself) to do it.

do you have the injector harness for the obd1 injectors ?

dizzy plugs arent really needed, just for cosmetic looks. and to make it look cleaner for hte wires you need to run from the ecu.

wait so i need an obd1 harness for the injector wiring but i dont need a new dizzy? Im confused...

your staying obd0 or going to obd1? if your staying obd0 then to make it look nice you should run obd0 si dist plugs. but its just for looks. if your going to switch to obd1 then you need a new dist.

when i did my mpfi swap, i got an si harness so its looked cherry, looked exactly stock even with the 4 wires i had to add because i put a connector on that so i could always unplug it if i had to pull the engine. it paid off because having to switch back to dpfi, my wiring harness was easy to understand and took me only 5 minutes

planning on the same conversion, i have a resistor off an si prelude (1 red wire and 4 black). do i need an si distributor, i mean is that nessasary(spell)?

you need a mpfi dist obd0

your staying obd0 or going to obd1? if your staying obd0 then to make it look nice you should run obd0 si dist plugs. but its just for looks. if your going to switch to obd1 then you need a new dist.

when i did my mpfi swap, i got an si harness so its looked cherry, looked exactly stock even with the 4 wires i had to add because i put a connector on that so i could always unplug it if i had to pull the engine. it paid off because having to switch back to dpfi, my wiring harness was easy to understand and took me only 5 minutes

so i can keep my dizzy, but what are the dizzy plugs? Because im gonna stay obd0 for now until i do an engine swap if i do one at all. But i wouldnt have to have a new dizzy at all bc im stayin obd0 right? I know i need a new ecu and thats not a problem. I can always get my friends LS ecu. So lemme get this straight. Heres the list of things i NEED.

1. Throttle body with the sensor that sits on it (obd1) (its a vx manifold)
2. OBD0 ECU mpfi
3. OBD1 Injector harness
4. Then i just need to run 4 wires

I have the manifold with injectors and all i just need the throttle body with a sensor bc my friend may not be able to find his.

Please correct this list if its wrong.

you do need a mpfi dist. a dpfi dist is missing the crank angle sensor, which a mpfi dist has. also the mpfi dist plugs, by that i mean the wire connectors, are round, while the dpfi is square and not enough to hold all the mpfi wires.

How About The Resistor?,,,so Far I Have Di6a6ecu,maifold,resistor,and Planning To Run 4 Wires. Stil Alittle Fuzzy.

i have obd1 plugs. I have a VX intake manifold.

mpfi injectors are low impedence, you would need a resistor or a low impedence sending ecu.

mpfi injectors are low impedence, you would need a resistor or a low impedence sending ecu.

no no no. every ecu sends the same signal whether its high or low impedance injectors. the difference is the power to the injectors.

obd0 injectors need a resistor box
obd1 injectors dont need a reisstor box

this has been done before...i actually posted about it. I did it for my car....it is a much cleaner look. But, it is a whole lot easier to add 4 wires than to repin the whole engine harness....you'd need the diagrams (which i've made myself) to do it.

yeah, me too. ive done it. originally i made a subharness with DPFI engine interconnect plugs and MPFI body interconnect plugs, but it was too much wiring in the engine bay for my taste. anyone whos seen pictures of my black engine bay with all the red loom knows what i mean.

so i just changed it, using the Si engine harness with the interconnect plugs repinned. i even went a bit further and moved 4 of the wires from that 6 pin plug on the passenger side over to the drivers side plug (because thats where they are orginally in the DPFI harness) left the 2 wires for the cylinder sensor on that side, and used the 4 spare holes in the 6 pin plug for the knock sensor, VTEC solenoid, VTEC pressure, and 2nd O2 sensor.

anyway, it looks stock now.

sounds alot harder than just modifying the dpfi harness for mpfi

sounds alot harder than just modifying the dpfi harness for mpfi


it is a bit more work, but it comes out a lot cleaner. i didnt even have to cut and splice wires. everything is still original factory wires, just mixed and matched from an MPFI and a DPFI harness. oh, and a hasport subharness.

yeah but i covered all my splicing with heater insulation cover, fuck i cant think of what its called right now, so you could even see it and it looked stock. just depends on how much time your willing to take to make it look nice. i didnt want mine looking like shit so i took the time to make it nice. looked stock to me

yeah, thats the best way to splice. i figured since i have all of these harnesses lying around, i could do it this way and have the most reliable harness possible.