My Autometer fuel mixture gauge is reading lean since installing it. I thought it was the gauge until I have placed a digital voltage reader on the sending wire and ground near the sensor, and it reads .03 to .12 when running, .04 when not started.

Autometer says that the reading should be from .01 to 1.0 for the gauge to display right. I swapped the recently replaced O2 sensor with my old one and I get the same low volatage (lean) readings on both sensors.

What gives ? Any help is appreciated since I do not want to run the L lean. I do not think it is running lean since the engine is not detonating or pinging.

Kevin T.

1994 White Gen1

 

I would think that if your truck is running lean that you should have some lean codes present, or if was just sticking O2 sensors, you'd have some slow response codes in there. You didn't mention your check engine light being on. I have never tried to monitor O2 voltage with a DVOM, so I don't know for sure if that method will work or not, most meters wouldn't switch fast enough to keep up with a properly switching 02 sensor. I'd suggest you get your truck hooked up to a Ford diagnostic tool that will allow you to accurately monitor the HEGO voltages and also check out your long and short fuel trims to see if your pcm is adding fuel to try and compensate for a lean condition. Also check for vacuum leaks. But again, you should have some codes stored and a check engine light if you had a real lean condition present. I'm not familiar with the autometer air/fuel guage nor do I know how accurate they generally are, but I suspect that your method of testing may be the culprit here.

hope this helps.

later,
chris