2002 Blazer Help O2 Sensor
 

I have been working on this for some time and just can not figure this out. It seems the ecu sends a test voltage on the blue wire to the o2 at startup. Most o2 sensors use the blue wire for the sensor signal. But from what I see the voltage on the blue runs 1v to .01volts (normal) but the white also fluctuates the same as the blue.

I added a EFIE device gas went down. Put Resistor on blue wire gas goes down, 15k resistor from white wire to ground gas mileage went up a little. or so it seems.

This does not make sense. So for this drawing what can you tell me about this o2 sensor?

Although the blue and white wires are on the o2 sensor, these colors are for the wiring harness.

Thanks for your help
https://www.freewebs.com/hhosurfer/ph...p/o2wiring.bmp

anyone can help here thanks

might help if you added a key as to which letter was which color...if blue is B, I think blue is the heater element (with the square wave lookin thingie). the alternating short-long lines means a voltage source and the arrow means variable thus that's the sensor. you need to put the EFIE on whatever P/W, T/W, T, and P wires are.

on a related note, don't you need a EFIE for EACH O2 sensor?

Yes I did add an EFIE but only the front 2 sensors.

(B) Black (P/W) Pink/White (T/W) Tan/White

The arrow is a variable battery of some sort (o2 sensor)

But what am I looking at? If EFIE drops mileage and adding a resistor in line on hte blue drops the mileage but shorting the white to ground using a resistor increases mileage?

Thanks

read my post.
-the arrow is the sensor so you need to tap the EFIE into the right one(s) of those wires. (T/W or P/W)
-black is ground (obviously)
-blue is the heater element (stop messing with it. cold sensors=bad as you found out)

where is the white wire? p/w ought to be pink with white stripe or bands.

Where exactly did you tap into the sensor wiring? in the engine bay/under the car?