Cat. Converter Question

[rws]

I have been experiencing a gradual loss of low end power and am starting to think my cat. converter is done, which is OK because my muffler has several holes in it and the rest of my exhaust system is barely there.  Tested back pressure right in front of the cat and it was quite high.  Has anybody put in a high flow cat or just put in a pipe?
Motor is a 1990 4.0L Renix.

[NUXJR]

Go see Al at Carline/Calgary Muffler by Chinook mall.  On my old 90 XJ they removed my cat & installed replacement pipe & new Turbo Z III muffler for $200-$300.  Had it done in like 45 minutes.  Tell em Rob from Courtesy sent ya :wink:

[TJ54]

I've got a magnaflow High flow Cat on order, It will be another week or 2 before it comes in.
My old cat was plugged big time, when I removed it there was a huge increase in power. I have two O2 sensors, one either side of the cat, My jeep ran well for a while, then started giving me problems which I still can't sort out. So I am going to put in the high flow and replace the O2 sensors. I have never replaced the sensors before So it's probably time any way.
Since your jeep only has the one upstream O2 sensor I'm guessing you will probably be ok without it.

[BlackYJ]

Ron you engine will respond very well to a high flow exhaust system.  From experience I would remove the cat and throw in a resonsator and put in a high flow muffler, I went with a Dynomax Super Turbo.  Also I recommend increasing the pipe size to at least 2.25" to 2.5".  Both my dad and I have done this formula on 3 jeeps all with great success.

For reference the Jeeps were:
90 XJ 4.0L
94 YJ 2.5L
95 YJ 2.5L / 4.0L

[rws]

Thanks for the info.  When I found the price of a new cat I thought I better look at a few options

[2360]

I've got an old 88 Commanche (480,000) that I bought back in 1990.

I had an exhaust leak at the cat, so I just replaced it with pipe. Turned out I had to also replace the pipe from manifold to cat.  I hacked off part of the cat which had the support to the transmission crossmember and used it on the pipe.  For a first timer on exhaust repair, I think I did OK.

The cat was in bad shape, I looked down the hole and I could see light coming through.   The mesh just inside the cat was almost a solid mesh.

One thing I've noticed, my beater got more pep now.

[Asia]

Yeah my '95 YJ, 2.5 liter was gutless, the cat was plugged with broken bits of the mesh/core.  Calgary muffler cut it out and welded in a straight piece of pipe - fairly cheap.  My O2 sensor is upsteam of the cat and removing it didn't cause any problems.  The Heep now runs much stronger and it's alittle throatier - I like it  

[rws]

Great info.  Thanks