[Capt Fiero]

I have a 93 Elderado motor and it has dual O2 sensors. I hooked up the meter to the Purple wire in the large green PCM harness. However the O2 meter stays pegged in the rich side without moving. I know the car is running rich, but not nearly as rich as the meter thinks I am running.

Anyone got any suggestions or should I just have a 3rd O2 sensor bung welded in.

 

[Cadillac_Rancher]

If it were me....Id have to weld in a 3rd bung. remember how an o2 sensor works, it generates small ammounts of voltage, it is not a resistor of some kind that simply returns voltage based on its samplings. so when you plice from a .01volt-1volt wire, there will be lots of loss.


-The Caddilac Rancher

 

[N0DIH]

Does the ECM agree (is this a 4.9L car?) on the diagnostic display?

The O2 sensors have such a narrow window between full rich (as indicated) vs full lean (as indicated), compared to reality. A reading of .9v is considered rich, but is really only around 14:1 A/F. GM did calibrate most if not all cars rich at WOT, as the cat converters (monolithic) will melt.

 

[Capt Fiero]

Yep the scan tool recongnizes everything just fine.

(I don't have a diagnostic screen in the car though)