XJS

I am fairly new to the world of Jeeps, but I really enjoying fixing mine. I love the feeling knowing I conquered a problem and came to a solution myself. Unfortunately I am facing one I don't know how to fix.

Here is what happen:

I was driving my Jeep down a dirt road when a rock jumped up hit the under carriage of my car. The rock knocked my muffler assembly apart right before the catalytic converter. This also ripped the wires out of my downstream oxygen sensor. I pieced the assembly together, replaced the downstream oxygen sensor, and allowed the computer to properly reset. A few miles later
The check engine light came on telling me the upstream oxygen sensor had
short. I replaced that sensor and the check engine light returned.

Here is what the car is doing now:

Rough idol and misfires
extremely low MPG
low engine performance

Car Info:
1999 Jeep Cherokee Sport (XJ)
6cyl 4.0L
Approx. 180,000 miles

I took the car to a garage and they did a electrical diagnostic only to tell
me the new o2 sensor I installed was bad. They put another o2 sensor in and
the problems continued. I took it back and they changed the fuse, and put a
fuse in they said was missing. No improvement. So I am currently up to
$470.00 in garage fees with no improvement. I ran the codes and none are
coming up saying I have a bad Catalytic converter. My gut is saying it is
the Catalytic converter, but the garage thinks it is my computer and wants
to charge $700 to install a new one.

If it is the computer, how hard is it to change? Could I get one from a scrap yard to swap out, and what would be the steps to replacing it?

Any help would be very appreciated, and thank you for taking the time to read.

Dwestonxj

This sounds dumb but check your spark plugs .. My girlfriends car acted the same way and threw the o2 code .. I replaced both and that didn't help... Pulled the plugs and put in new And it runs like a champ now

tjwalker

If you are STILL setting a code, you must follow that code! The fact that you have a code (cel) and symptoms is not a coincidence. I doubt very much that this is the computer.

Please post the exact code you have. With OBD, the devil is in the details.