Datalogging ???

[J.bo]

I was datalogging and I notice that my battery voltage would drop from 13.5 to 10.7 then back up to 13.5. Is this telling me my alternator is going bad? Also, one of my O2 sensors is moving slower than the other. So is this also telling me that my O2 sensor is lazy or what?

[JoeBoomz]

Alternator may be turning off during WOT runs, were you doing that while logging?

Also your o2 on one side might be getting different signals than the other if there is a variance between spark plug gap or coil performance. It doesn't hurt to change the o2 sensors if the car is higher mileage though.

[J.bo]

I was just sitting at idle datalogging. So to me it seems that I should have a constant and not a drop in voltage. Mileage on the o2's are 120k. I may change them.

[Windsor58]

Originally Posted by J.bo

I was datalogging and I notice that my battery voltage would drop from 13.5 to 10.7 then back up to 13.5. Is this telling me my alternator is going bad? Also, one of my O2 sensors is moving slower than the other. So is this also telling me that my O2 sensor is lazy or what?

Was your air conditioner on? When the compressor kicks on, my voltage drops. Goes back up when the compressor kicks off. Especially if there are any other loads on it like headlights, high fan setting (for the AC), stereo, etc.