O2 sensor help

[Rugger187]

Hoping someone can help me.
I rebuilt my 350TBI in my 89 a few months back. I had the local shop put the motor back in and hook everything up.
They did a decent job, cleaned the bay, re-wire loomed everything, and re-taped everything that needed it.
Maybe they were a little overzealous though because my O2 sensor never got hooked up and I cannot find the dang wire.
Can anyone post a pic of what loom it came out of? Before I start tearing all of them apart?
Maybe that will help me find it.

 

[1-ton]

If this garage did not connect your O2 sensor, then they did not do a good job! Your truck is now running full rich in "open loop". This explains the crappy gas milage.

The O2 sensor wire and terminal end is routed along with the transmission wiring harness. Look in the area of your transmission (left side) for the O2 sensor terminal to be dangling there somewhere disconected.

 

[Rugger187]

Thanks. I found it where you said.

 

[1-ton]

Your Welcome. You should notice a big difference in how your truck runs now.

 

[Fordum]

Be warned, O2 sensors have to have an outside air reference in order to work. Amazingly enough, most of them get it down the wire from the connector.
In other words, the outside oxygen migrates down the wire inside the insulation.

If you use the connector, everything is fine. If you cut the connector off, splice the wire and then seal the connection with tape or heat shrink, you will often stop the sensor from working.

 

[Rugger187]

Now that is interesting. I never heard of that.
I need to start looking into burning my own chips and doing my own tuning. Finding someone to do it nowadays is getting hard.