I'm in the process of converting my 351w to tbi (gm fuel injection). All sensors are in place, the wiring harness and ECM are installed. Because this is being used in a boat, I am not using:

vss
egr
knock
any transmission related ssensors
anything related to air conditioning

I've downloaded tuner pro rt and purchased a serial cable. I've started to datalog and noticed something strange. I'm using a wide band o2 sensor to see my afr. The narrow band o2 sensor is unplugged. I am still seeing o2 crosses and voltage readings while data logging. How can this be, there is no o2 sensor information being sent to the ECM, right? I would also assume a error code would of been tripped.