Fault Codes/Check Engine Light

This is ridiculous - I just got my XJ last month and everything was working fine - granted there were some mechanical issues I knew I'd have to fix (catalytic converter rattling, main seal needed to be replaced)...but a week after I got it home (bought it 2.5 hours away from where I live)...the check engine light came on. Got it scanned and the tech told me that the code was for a misfire on the cylinders. So I went home and switched out all the spark plugs and plug wires (yes I gapped them correctly). Disconnected the battery to reset the computer and was good to go...for 3 days...

This time I knew something was up because the radiator busted...leaking everywhere...got that replaced (metal radiator replaced the cracked plastic one)

The tech that fixed it didn't reset the computer (I forgot to ask him...and I haven't had time to reset it myself by disconnecting the battery)...final straw tonite...I got the catalytic converter replaced this afternoon and it sounds a heckuva lot better than it did...then I go out and pick up a friend for a movie 3 hours later and the stupid Jeep starts acting up...initially I thought I was just imagining things - but noticed the RPM's jumping and the Jeep was hesitating when I was trying to accelerate...it wouldn't accelerate...and then it would rev up and speed up really quickly...

Did the on/off method of retrieving the fault codes and came up with 3 different codes - when I looked them up online (didn't have a manual handy) 2 were wiring problems with the O2 and A/C...the other was misfiring on the cylinders again...

Are there any other problems this could be? I'm getting pretty sick of shelling out this amount of money and I've only had it for a month - I was planning on taking the money I've spent on fixing it up for a lift kit and some other mods I
wanted to do...

Any advice or helpful hints are appreciated...I don't want to throw in the towel but I'm ready to give in

Sounds like the o2 sensor on the cat is playing up, maybe good idea to check out the wiring to it. Seems too much of a coincidence that you should change the cat then get an oxygen sensor fault. O2 sensor would cause the problems you are having.

Pete

The O2 sensor could be causing the acceleration problems?

RokeeChick said:

The O2 sensor could be causing the acceleration problems?

Click to expand...

Yes it it's telling the engine to go rich and then lean. Generally when you do a cat you should do the O2 on general principals. Might also be time for a really good once over, I only use OEM plugs, cap, rotor and wires. I think I would also tend to stay with an OEM O2 sensor. Then I would do the disconnect and reconnect of the battery. I would also do a very good job of cleaning the throttle body off the engine on a bench, careful not to use plastic hostile cleaners on the sensors there. You need to get it back to a baseline. I would also invest some hours disconnecting, cleaning and reconnecting every plug you can find. Remove all the grounds and clean them up on both the wire and the body, make up a past of baking soda and water and clean the battery terminals, the put a coat of protective grease on them

if whoever replaced the convertor didnt properly route the o2 sensor wiring after installation, the o2 wiring can contact the drive shaft and rub or pull he wiring from the sensor. still if one o2 sensor goes bad i would replace both. the other deteriorates and doesnt have an accurate reading compared to the other. just a suggestion.