Ok I'm stuck here. My jeep is throwing a code 21 yet again. It happened a month ago, I replaced the o2 sensor, reset the computer and cleaned the pcm connection with crc electronic cleaner. A couple days ago, it happened again, so I reset the computer and cleaned the pcm connection, again. Well, the cel is back on again, came on when I was going to work this afternoon, and it was still on when I came home.
When it happened a month ago, the engine was running either rich or lean, but either way it was running like ****. When I got home, all of 10 minutes ago, after I put it in park, it was running normal, but then I revved the engine a tiny bit, and it seemed to have sparked an erratic idle. Not running rich or lean, but it just jumps up to above 1k rpm's and back down randomly.
So my question is, what could possibly be causing this? I got a pm from another member saying it might be because my plenum gasket needs to be replaced (typical plenum repair). Would a bad plenum cause the sensor to go bad? Also, I ****ed up my y pipe back in the spring, and quite possibly cracked my exhaust manifold since I hear an exhaust leak whenever the engine is cold (manifold expands once it gets warm).
Is there a cord I can buy online that will let me hook my laptop up to one of the diagnostic plugs to see if I can see how its running? (obd1, I know there are like 3 plugs) A guy came into work once and said thats what he had to do, he said he was going through o2 sensors as well.
What are my options here?