88 EF Hatch

so i used to have obd0 ls and had done dpfi to mpfi wiring myself. new i put in obd1 b16 with obd1 dizzy and obd1 p28. i kept my injectors wired up to injector resistor box and motor doesnt start. i read on some one elses post that you dont need resistor box for obd1 ecu and that instead of running negative injector wires to resistor and 2 yellow/black wires from dx harness to resistor box, you actually need to run negative injector wires straight to 2 yellow/black wires. can anyone validate this?

GhostAccord

You shouldn't run low impedance injectors without a resistor box. However that being said, you should be able to run the low impedance injectors and resistor box with the P28. I used a chipped P28 to run my low impedance, resistor box, Accord for 2 years. I think there may be something else causing your no start issue.

What ECU pins are you currently using for your fuel injectors?

OBD1 P28 injector wiring
Pin A1 = Injector #1 (BRN)
Pin A2 = Injector #4 (YEL)
Pin A3 = Injector #2 (RED)
Pin A5 = Injector #3 (BLU)

As for removing the resistor box you do not want to run your negative (ground) wires to the YEL/BLK 12v positive wires. The injectors negative (ground) wires run from the injectors to there corresponding ECU pins. These wires would usually be the solid coloured wires. They are RED, YEL, BLU, BRN in a stock wire harness. The YEL/BLK wires are the injectors 12v power source. Without the resistor that power source is 11-13 Ohms.

After you remove the resistor box. You need to splice the YEL/BLK wire into the 4 wires that were previously going from the resistor box to each Injector. Note* You will also have to replace your low impedance injectors with high impedance injectors if you remove the resistor box.

88 EF Hatch

Hmmm....reeally ok...anybody else have input?

KWayRacing

You say you "kept" your injectors do you mean your old LS injectors or that you retained your resistor box and used the injectors that came with the OBD1 B16. If you kept your injectors you should be fine...there is another reason your car is not starting. But if you kept the resistor box but are using the OBD1 injectors that came with the OBD1 B16 then that is not correct. Either use OBD0 injectors and retain resistor box or you can remove your resistor box and use the OBD 1 injectors. There are two methods to doing this. Both have the same outcome one is just more permanent. Take the harness that plugs into the resistor box and cut it. Take all four red wires and join them with the yel/blk wire. Or (less permanent and you must sacrifice a resistor box) Do the same thing(join 4 reds with yel/blk except on the resistor box side of the harness. I prefer the latter just because I can still PNP back to a resistor box. I prefer to keep the resistor box becuase I turbo my cars and I just prefer a peak and hold injector over saturated. Note: Never use low impedance aka peak and hold aka OBD0 injectors without a resistor box. Hope this helps.

GhostAccord

Note* Some wire colours may not match your harness exactly.

Hope this helps, it always seems that diagrams are a better way to explain things on H-T.

nani

sorry for bumping an old thread but one thing that is not clear to me is: where all the power wires that were spliced together go? on a OBD1 ecu with no resistor box? thanks!

beej

Bump, I have the same question...only I'm working with a std, so there is no resistor box. Going to obd1 and using my obd1 injectors I know I can skip the box, just not sure where to wire them to.

Mr. EG

The TPS wires also need to be switched or else the ECU will read WOT at closed throttle.

tapia7

ahh i have a 96 dx..i have no idea wha this is but i heard it will make it better?

schock3

moved https://honda-tech.com/forums/showth...mmies+w%2Fpics

Virgle DeBord

*urgent*urgent* I put a obd1 ITM on a p75 obd1 ecu but i'm not sure I did it right could someone send me a link please? 90 RS, obd2 B20b motor, all obd1 jumper harnesses on a obd0 harness... TPS wires? injector wiring? ran fine before the swap over. i notice the obd1 has less lines underneath the TB so.. perhaps I'm not deleting something correctly or hooking up lines incorrectly, thanks for the help