Hello. Quick question. 1993 XJ Sport. 4.0L auto. Last weekend my exhaust broke apart. (Well it had been rusting where the hanger weld used to be for years) When the pipe broke it hit the road and also bent in my catalytic convertor a bit. I removed everything from before the catalytic convertor back just to get home but as you can guess it was LOUD. Plus with the exhaust ending right under the passenger seat if I sat still fumes were rising.

Since it's in the teens and chances of snow forecast in the coming week and I want to quiet this thing down I plan to just run a piece of flex pipe from the broke off exhaust pipe back to the muffler. The flex pipe will basically be filling the catalytic convertors spot. This will turn a long cold exhaust job into a 15 minute exhaust job.

As soon as it warms up I plan to redo the exhaust correctly. Should I expect any problems running without a convertor for awhile? Thanks

 

I take it the O2 sensors were wiped out too? If so, expect a check engine light and possibility of running very rich

 

If the pre cat o2 sensor is installed, it'll be fine. Post cat o2 only monitors the status of the cat and DOES NOT affect a/f ratio. As mentioned above, you'll have a CEL until you reinstall the sensor

 

I don't run a cat in my 95 nor do I have a downstream o2 sensor pugged in at all. No codes.

My 96 needed an o2 spacer once the cat was gutted to keep the CEL for cat inefficiency off.

 

Engineering "solutions" like this usually fail at the worst possible time. Make an appointment at a shop, it will be repaired correctly and you won't have to worry about it again for years.

 

There's more than one O2 sensor on a '93 XJ? I have a '93 and a '94 XJ and have only ever seen the one in the down pipe in front of the drivers seat area below the firewall. In any event this O2 sensor is fine on my XJ.

 

The term "temporary" doesn't work for me... Once a cat, biological or mechanical is removed from my car I don't want it back again.

 

I purchased my '88 MJ from a guy who lives in an area of Ontario where emissions inspections are not required (north of Toronto but not that far). It's common, apparently, for cats to be removed. He said he ran it for about 8 years without one. It ran great when I got it.

I had to get an emissions test in order to get it certified. I took it to a shop that installed a new cat and then tested it. It passed with no issues. I drove it before and now after and I can't tell the difference. It still runs great.

 

To be honest, the 4.0 isn't enough motor to make any difference in power with a cat on. The Hellcat motor and the 690 hp vette engine have them and they do just fine

 

What I would do is check your local laws and see if you require a cat to drive legally and/or pass your state inspection. If you do, then I'd never advise skirting the law, but your Jeep would theoretically operate with the flex pipe solution. If you don't require the cat, then it sounds like you're fine to just run a pipe straight from what's left of your pipe out to the muffler.
I had to put a new muffler on my 95 when I bought it (it had none prior to me owning it), but it did have the cat and enough pipe to connect up to the new muffler. The new muffler and tail pipe cost less than $100 and were in stock at my local Advance.
I was surprised that my 95 was exempt from MA emissions testing for the state inspection - usually MA is a real PITA about that sort of stuff.

 

At 10psi from an m90 at 4krpm it was enough to turn the catalysts sideways on my 96 4L. Plugged the exhaust and shut down the engine. Not all cats are rated for the same flow rates and efficiencies.

 

No issues not running a cat on my 97.