I have a 94 Civic Hatchback Si with a B16 and I am running a stock P30. I pulled the motor and rebuilt the engine. I also replaced the engine harness due to the past owners lack of wiring skills. Well when I put the motor back in and went to start it up and as soon as I turned the key on I got a check engine light for the primary heated O2. The car cranked fine but idled funny and when I tried to rev it up it acted like it was choking out and died. I got a new O2 and still had the same problem. Well the dash harness was in pretty bad shape too so I replaced that next. I also put my ecu in my other car to see if I got the same light and it worked fine in my other car so I know the ecu is good. So after replacing the engine harness, O2 sensor, and dash harness I should have eliminated all possible problems (bad wiring or bad O2). I am still getting the same light and the engine still dies when I try and rev it up. If anyone has any input on this matter it would be greatly appreciated.