Over the last week or so, my YJ started having some problems accelerating. It started fine and first gear was not a problem. Going to 2nd, it would pause before responding to me pushing on the accelerator. Same for 3rd. 4th and 5th gears it ran fine. I knew something was not right and just hoped that it would hold out until today. This morning, I was making my last ride in it running some errands before my son and I would start tearing it down to take the tub off to address a couple spots on the frame and then rust proof the frame inside and out. We'll also be restoring the tub and replacing a lot of parts due to lack of maintenance from previous owners.
Anyway, this morning it ran the same as the last week until it got warmed up. It coughed and sputtered, lost power and eventually died on the side of the road. I tried restarting it and after a couple tries, it did start but could only run between 1500 to 3000 RPM. Outside that, it would cough, sputter and die.The CEL never came on but it does come on when starting it. I managed to limp it home (about a mile). First thing I did was to check the codes.
12 - Battery recently disconnected... Last fall was the last time I disconnected the battery to replace cables. It is driven daily.
33 - AC shorted... The Jeep never had AC and I understand its normal to receive this code on a YJ with no AC.
55 - End of codes.
I disconnected the battery for a few minutes and then started the Jeep again. It started the first try but within a minute started the same behavior and died. I checked the codes again and got the same three codes.
The only thing I noticed out of the ordinary was that the temp gauge registered about 150*. The Jeep had been running for a good half hour so the temp should have been much higher. Side note on this... Last winter, the temp gauge was fluctuating a lot. Thanks to guidance here, I installed a new thermostat and all was good.
The down pipe from the exhaust manifold has a leak in it. That will be replaced along with a catalytic converter since the PO removed the one it had. I figured that since it had a leak for some time (before I bought it) that the O2 sensor could be going out and purchased a new one along with the new down pipe and cat. The problem with trying to get it running again right now is that doing so would set me back in being able to get the rest of the work done that I have scheduled. My son and I can do the body welding but we are having a professional welder do the frame repairs. It will be a few weeks to a couple months before we are ready to put the tub back on and work on getting it running again.
Given the symptoms, is it possible that the O2 sensor just happened to give out on the day we had planned for some time to start tearing it down? At this point, I'm not going to try starting it again for at least a few weeks. While we have everything apart, what else should we be checking? I don't have a problem with buying additional parts, but I would prefer to check things out before throwing cash at something that doesn't need to have cash thrown at it.
Many thanks for any ideas.