i need help on 88-91 civic 2nd o2 sensor rig

[1manswap]

i need help. i am doin a 88-91 civic dx swap and puttin in a 1st gen b16a motor and i have the pr3 ecu. i have everything pluged in exept the 2nd o2 sensor. i tried to rig the 1st o2 sensor and split it to the 2nd o2 so it hooks up to both spots in the ecu (c8 and c16). I heard u can juss do it that way but it will run a little rich because it wont read a pair of pistons. But it still blinks 2. 2 is the 2nd o2 sensor. Do i really need to weld another o2 sensor or is there another way i can rig it????????

[Aspirate]

OBD0 VTEC ecus need two O2 sensors to tune for partial throttle (closed loop). The O2 sensor that has to read cylinders 1 & 4, must read 1 & 4. Same goes for the other O2, it must read cylinders 2 & 3. Other methods of wiring the O2 signals might work, but the ecu will get confused at partial throttle which is where we spend most of our driving.

I saved a quote from "Honda Admin":

If you wire one o2 sensor into both ECU o2 pins, the ECU will get confused with the readings it sees from the o2 sensor, and the short term fuel adjustments will bounce from lean to rich. The upshot is that the car will run badly, but will suddenly come alive once sufficient throttle is given to force the ECU to run open loop. If you wire two o2 sensors located in the main pipe into both ECU pins, then the ECU will start to do all sorts of things with the mixture. Often one pair of cylinders will run full rich, and the other full lean. I?ve datalogged this and seen +30% fuel on one pair, and -30% on the other. Sometimes the cylinder pairs will oscillate from full lean to full rich. The car will not run well. The best solution is to run a JDM header with two o2 sensors - difficult I admit with a turbo.

-Hondata Admin

[marklamond]

Hondata told me that i could load a particular ROM into my PW0-000 (similar to your PR3) and the car would always run open loop. Not quite a solution, more of a workaround but with some good tuning with a wideband i *hope* the difference in fuel economy won't be too much?

I don't know if they offer such a map for the PR3?

[pharnos]

Ok, just piggy-backing onto here...

When installing an air/fuel ratio gauge, which O2 sensor should you wire the gauges "O2 sensor" wire into? O21 or O22?

or doesn't it matter?

Cheers

Steve.

[Sleeper]

Ill give this a shot! if Im correct one is in the header and one is in the final collector near the flex pipe...since you dont want to get readings off one cylinder Id go with the other...caution most over the counter gauges are still very inaccurate...since we cant afford MOTEC... Greddy offers probably the best one out right now for about $400...comes complete with its own o2 sensor and processor with warning indicator for rich/lean conditions