Odd o2 Sensor readings

toygeek · Nov 12th, 2003, 02:31 AM

In the quest to diagnose a bad running motor that is quite intermittent, I ran a wire to my o2 sensor, and hooked up a volt meter so I could monitor while driving.

I found that most of the time, it stays under .1 volts, which is very lean. When I hit the accelerator, it goes to rich at over .8 volts, obviously because of the accelerator pump. Whether its running decent or it is doing really bad and barely running, it stays at 0-.1 tops.

SO, am I looking at a bad carb? It is a hopeless chokeless that has about 300k miles on it, it wouldn't surprise me. In the interest of getting it running good before I go EFI, I think a junkyard carb might be the ticket.

Thoughts?

RiceBox · Nov 12th, 2003, 01:20 PM

Junkyard carb probably wouldn't help either, because it is most likely in crappy shape too. Get yours rebuilt or maybe you just need a new O2 sensor.

toygeek · Nov 12th, 2003, 01:26 PM

Well I found this morning that I had a bad ground to my meter. I'm running a new ground to battery and will try that today, and see what happens.

toygeek · Nov 12th, 2003, 06:41 PM

Well, I managed to get a better gound (at the battery

) and found out that my previous readings were dead on, just about .01 volts off. It reads under .1 volts at any given speed, creeps up to .2 volts if it idles for about 3 minutes, and goes back to .01-.05 at any other speed. When you give it gas, the accelerator pump richens the mixture and the voltage goes up to between .5 to .9 volts.

I am thinking this thing has a primary jet clogged. Does anyone else agree? I'm pulling the plugs tonight to see if they look like its been running lean, as the o2 sensor indicates.

Thanks