Contour Enthusiasts Group Archives Forums General Troubleshooting Catalytic Converter

My catalytic converter on my 1996 Mystique is clogged, and instead of paying the $400 to get a new one, I think I'm going to just hollow mine out. Has anybody done this to their Mystique (or Contour) and have any tips? I looked under the car the other day quickly, and it looked like it actually may be welded together... which might be a pain in the butt.

Thanks!

There's an emmission warranty on the cats for 8 years. Check that out first to see if your covered.
Linky

First question to ask is, why is my main cat clogged?
Did the pre cats cause this by failing and clog it up?

A $400 repair for the main cat isn't as bad as $2500 for the pre cats. Linky #2

The consensious on these boards is to gut your pre cats and keep your main cat, as power is lost hollowing out the main cat.

I had gut my main cat, then gut my pre cats, drove around cats less. Recently I have replaced my main cat with a Magnaflow high flow cat.

I gutted my main cat about 2 years ago. Just make sure that it is actually your main cat that is clogged up. When you get the cat off, start the car to make sure it is not one of the precats that is clogged.

I gutted my main cat only to eventually find that one of my from precats were clogged. So I wasted two days instead of one. You can gut them pretty easily with a screwdriver and a hammer.

Also be careful that you don't break any bolts.

I have put another 60000 Km's on mine since I did this and have had no more problems.

When I was having my waterpump replaced, I had the autoshop take a look at the check engine light, and they analyzed it as the cats, and said it'd cost about 400 to replace, which makes me believe its the main one. I'll take the main one off tomorrow and check it out, and hopefully that's it.

Thanks for all the pictures and links, I'll let you know how I made out.

If its a CEL for the cats, it'll be the pre-cats as the main cats don't have the sensors.. and there's no way they're replacing your pre-cats for $400.

If it is your main cats, watch out.. alot of times its the crumbling pre-cats that fall into (and clog) the main cats. One of mine actually COMPLETELY DISINTIGRATED.. it gutted itself!!

Makes sense. So the jist that I got from the other threads I was linked to, it isn't good to hollow both the precats and the main cat? I would think that the free airflow through the two cats would help the engine run more efficiently, and give me a power boost/better fuel economy. Does it relieve backpressure to the point that the engine doesn't have enough?

The multiple changes in chamber volume slow the exhaust gas velocities and cause you to lose exhaust flow and therefore power. Your best option is to replace/gut the precats, and empty the debris out of the main cat, just pour it into a bucket. If the symptoms persist, you'll need to have your main cat replaced.

I don't know what your mechanical capabilities are, so if the Mystery Mod how to is not to your liking, you can get a set of gutted precats from buckshotmotorsports.com for under $100 (after your core return) and have those installed. Easy and comparatively cheap.