jarrett2k

Maybe I'm just wrong about the year. But it's in an EF Hatch, no o2. and it's the JDM spec

Fabrik8

That would mean open loop fueling from the factory. Doesn't happen.

thermal

are you running an aftermarket ECU? You have to have at least one O2 sensor if you are running an OBD1 ECU. I had a 98 JDM ITR motor as well which came with an OEM ECU. It was OBD2 and looked for 2 sensors. Either way, OBD1 or OBD2 will throw a CEL code if no O2 signal is sensed. It is not going to calculate your air/fuel ratio without it. You'd be on limp mode all day...

H22Boost

my friend ran his b16 with no o2 sensors and it really was no difference just check engine light was on but it wasnt in limp mode or nothing. prolly get worse gas milage tho.

time2op3nsh0p

get a ECU tune for no o2 sensors. What computer you running? You should definitily run 1 o2 sensor though. I think your mechanic might be confused

Fabrik8

That's a bad idea. Running permanently in open-loop mode has a large amount of compromises...

HypeRHatch

To the OP, in Japan the emissions is completely different than here. In this case using an OBD2A ECU will require the use of 2 Oxygen Sensors. If you want to be emissions friendly i recommend utilizing the OEM Header or Aftermarket header with the Bank1 Sensor 1 Bung. To have th second oxygen sensor you will need a OBD2a-OBD2b Civic Catalytic Converter 96-00 EX/99-00 Si which will have the converter after the header unlike the LX,HX,DX that have them on the manifold from the factory (D16y7).

Now if your using a JDM OBD2a P73 I believe you can get away with running just the one sensor it is mapped for since they do not use converters.
Like a couple people mentioned before me it all comes down to what ECU you are running.

Most Hondas now use a conversion harness and revert to OBD1 to expand chipping or using Hondata, Uberdata, Chrome, etc etc which in any case can be adjusted and have sensors turned off completely like Fabrik8 mentioned.

Fabrik8

No, you don't want to turn the O2 sensor feedback off. You don't want to run open loop on a street car, period. Too many compromises.

MoarLow

I had a 99 LX civic at one point. I looked into the b-series/vtec d-series swap and even with swapping the engine harness you won't get the engine running as it should like factory. You'd have to also replace the interior harness to add the O2 wiring in the ex/si stock location. Adding to the running in open loop issue, you'll be running rich all the time in open loop. Your fuel trims will be crap. That'd be the best solution to your problem. Another would be just getting a ex/si shell.