97 Xj sport 4.0. 160k miles. It has the original catalytic convertor on it and i have a high flow magnaflow sitting in the garage but haven't been able to put it on yet, would a bad cat cause my XJ to smell rich sometimes? I only smell rich maybe once every third start up, once it reaches operating temperature it will quit. the cat has been bad for 6 months and i'm changing it out in a few weeks. thought i'd ask and see if that would be the main cause.

 

It could be...

 

i think it is, all the bricks have come loose and it rattles really bad.......wouldn't pass inspection. im running dodge neon fuel injectors in it but that cant be the cause so we will see if changing it makes it quit.

 

Lota time, bad cat will smell like rotten eggs...

 

It's supposed to be one piece. If it's rattling it needs replacing. It's not doing it's designed job.
Dan

 

smells rich, u know gas smell.

i know this, i just haven't had time. i have the replacement.

 

That's when they're plugged up & before they go solid and start breaking up, I believe.
Dan

 

smelling rich could also be bad O2 sensors, or a bad/disconnected MAP/MAF sensor. I believe the 97's have 2 O2's one before the cat and one after. however if the cat is toast then it isn't heating up and burning off the unburned fuel.

 

Actually a brand new cat smells like sulpur or rotten eggs,when they get old they do not have any smell because they are not converting anything anymore. If it is rattling you would be wise to replace it now before it comes apart and ends up in your muffler and plugs it up as well.

 

im going to replace all of the pipe

o2's were just replaced because they got ripped apart so their fine. i'll check map

 

The problem with continuing to run with a rich condition is the sensors will get destroyed,Check them after you replace your exhaust and cat to make sure they are working right,because even though the cat may be removing and working right after you replace it,if it is still running rich the cat will get destroyed very quick. Just make sure everything is right or you will be going back and forth.