does haltech have there own o2 sensor?
 

My o2 sensor has 4 wires coming out with a gm weather pack connector on the end that plugs into my haltech harness. Im not sure what kind it is, it has AC on the sensor, so I thought I should ask and see, thanks.

Sounds lust like my Haltech 4-wire O2 sensor. Do the four wires go into a 3-prong weather pack. If it does and it is indeed a haltech O2 sensor, wire all 3 wires from the main harness as per the wiring diagram from the haltech. This is at least with an E6K and E6X. Apparently the 4th wire only aids in idling when there are still cats or something like that. I poured over the Yahoo Haltech support list last night and read that on one of Hitmans posts.