Recently I got a 91 ls and a 93 integra. After the swap though I get code 4 anytime I drive it and kicks into a limp-like mode and won't rev past 3.5k rpms. I more or less swapped everything from the 93 (wrecked) into the 91. Before I started I had no idea that one was obd1 and one was obd0 so this has been a learning experience to say the least, but to my knowledge I have done everything for the conversion right...(apparently not because now I'm here lol).
I have installed the obd1 ecu
obd1 injectors
obd1 dizzy
And a conversion plug for the obd1 dizzy to obd0 harness as well as a jumper for the obd1 ecu to obd0 wiring.
as I stated above though it gets code 4 (distributor sensor) and wont go over 3.5k rpms, now I have read lots of posts with this problem but they all replaced the dizzy or found they wired it wrong, and it worked fine. So I bought the conversion plugs to take that possibility out and ordered a brand new distributor...but still the same code 4. So now I am completely lost, the vehicle worked fine before I converted it to obd1...so logic would say something I changed made the problem, but I have replaced the dizzy and that didn't fix it...could it be the ecu? Would there be other signs than just this if it is the ecu? Also could the jumper for the ecu be wired wrong? The dizzy and car's internal wiring is fine...plz help I have ran out of ideas.

 

I had a similar problem converting my 2001 integra from odb2 to obd1, bought the conversion harness and everything. I wound up purchasing a custom Rywire harness made for my cars needs..it fixed the problem .

 

I just found a thread, in it the guy traced the wires on the ecu jumper harness that go to the crank sensor b15 and b16 on the obd0 side of the harness and saw that b16 spliced and went to what should be an o2 sensor pin. I looked at mine and it is doing the same thing. One of the crank sensor wires is spliced off and also goes to the obd1 crank sensor pin and o2 sensor pin...so I cut the o2 side of the splice and now the car runs normally again. Hard to believe after all this that was it but....it was have drivin it over 3.5 k rpms now for a day or so and no problems. Not sure why the harness I ordered was the problem it was the right one. *shrug*

 

Its common to get a funky ECU jumper harness, RYwire, and Pheriable are reputable companies i would go with.

 

RYwire is who I used, I just sprung for a tucked harness.