This is my O2 Sensor diagram. The original single wire O2 was replaced with a powered 3-wire O2 Sensor detailed below.

   In case you don't know the factory sensor for this truck is a single (sensor) wire only. A heated O2 sensor helps by "burning off" deposits, making the sensor live a longer life. Additionally, a heated O2 sensor helps cut emissions by becoming active faster than a non-heated unit. This should also help me at idle when my exhaust cools down. As you may know the oxygen sensor does not send a signal until it reaches 600.

   I just ran a fused ignition wire from the fuse block, ran ground to firewall and teed in to existing O2 sensor wire (purple). I also wired in the factory connector so the next time I replace this sensor I can just unplug it and plug in the new one. It warms up much quicker and should help keep the sensor cleaner. I asked my parts buddy (Eddie) at work to find me a GM 3-wire O2 sensor. He found one for a 95 Astro Van with a 4.3L. Sensor# 025312185, harness # 012117025. 

Note: O2 sensor voltage reading=air/fuel ratio i.e.: .1v=17:1, .3v=16:1, .5v=14.9, .7v=13.8:1, .9v=12.7:1.

Read here about "Testing an O2 Sensor".

Holley/GM TBI Info
Tuning a TBI fuel system for a Supercharger
Adjusting Boost Pressure
Supercharger Bypass valve

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