I realize there are some things that must be present to throw a code, but I didn't have an O2 Sensor in my car when I initially fired her up, and ran like that for ~1.5 weeks. Never threw a code. But I also never drove the car or anything.. but she did get up to operating temp during that time. Although you do have an OBDII setup and all that wonderful greatness.. just saying it may never even throw a code. However, mine has the availability for the system running overly rich, or overly lean.. so if your'* was operating correctly, it probably would have thrown that code if you could smell gas from it. Usually a misfire is audible [at least, in my experience with them]. So, i'd think you could hear it. But you never know.
'89 SSE - GX3 -190k, 155k on body - Back for another ride.