Just registered my 94 Jeep Cherokee emissions no longer required. What are the pro's and con's of removing the catalytic converter? I'm sure it's bad was replaced about 3 years ago. Thanks.

 

The twin cats on my 2000 WJ are 20 years old with 257K miles on them and are still functioning properly. If yours is only 3 years old, what makes you think it's bad? With OBDI systems, it shouldn't make any kind of difference if you've got one or not, I would think. With OBDII systems, the computer uses O2 sensor readings to adjust fuel mixtures so cats are important. OBDI will still have an O2 sensor, but it's not that critical.

 

Why do you think it's bad? Just because no one is checking or enforcing it locally, it's still not legal to remove it.

 

Won't hurt anything to remove it, I haven't had one on my 97 since I have owned it. The front O2 sensor on OBD1 and OBD2 XJs is what the computer uses for your air fuel ratio. The rear O2 sensor on the OBD2 XJ is only there to monitor the cat and has no effect on how the engine runs.

 

I replaced the injectors about 8 years ago to the four hole and the motor has 325K miles. Basically, I was replacing the cat every two years due to a rich fuel condition.
when it was replaced it passed emissions. It's been three years since the last cat.

 

Find out why your fuel trims are wrong and save yourself money on gas.

 

X2. You have a problem that is killing cats. The solution is not to remove the cat. That's like painting over an idiot light to solve the problem of the red light coming on.

I have no beef with removing the cat, mind you, but that isn't your problem.



Actually, on the later ones, both the upstream and the downstream are used to adjust the fuel ratio. I know it's NOT used for my 97 (which is OBDII), but I haven't yet run down the exact year it changed. I know the downstream (after the cat) sensor is used for at least the 2000 and 2001, so maybe when they went to coil packs. I'm pretty sure it's used for the California emissions versions.

 

What kind of oil consumption is it doing? Burning oil will kill your cat too, which is part of the reason the zinc dialkyl dithio phosphate was reduced to prevent phosphate contamination of the cat.

 

I've heard that statement before, but I can't see how the downstream sensor can provide any precise knowledge about the fuel trim. I thought it was just there to assess whether the cat converter was working. I could also serve as a secondary sanity check whether the upstream sensor has failed. It should cycle some, and a failure of the upstream might show up as the rear screaming very rich lean but the upstream says it's lean. In theory, if the cat is working the downstream should always read leaner, right?

 

half a quart every month or so.