pull the main cat out and try to get the pieces out before it causes a blockage and you really f something up

 

what did the plugs look like when you pulled the original set? Have you done a compression check? What does oil look AND smell like? Do you have a feel for oil consumption? Had the exhaust manifold been previously removed?
The catalyst material would go downstream and it appears to me like someone tried to purposefully remove the material rather than the catalyst deteriorated(but there are others here who would be better judges than me on that issue).
What you dont want is clogged catalytic converters which cause backpressure into the motor affecting the piston rings. There is no simple fix for that problem. Pull the secondary cat and see what happened to that precat material. It has to be somewhere in the system unless someone made a very poor effort to gut the cat YMMV

 

Clean out the main cat and then use a screw driver and hammer to finish the job on the precats. Put it back together and drive it. Any damage done is already done and you really can't fix it. There is a reason everyone here says the first thing you should do after buying a 2000-2002 MR2 is gut the pre-cats.

 

This. There is not much you can do if any damage has been done already. Maintain and check the oil frequently.

 

First of all thanks for everyone's quick responds.

I have the downpipe off the car, but I don't really understand how I should "clean" it, especially since I can't see the condition of the cat interior. How do I "clean" the main cat?

 

You can use a borescope to see around the corner or just use a garden hose and back flush the cat with water.

 

You're worried about nothing. If the car's going to burn oil, the primary cause is not going to be because of the cats. Early 1zz's have a known piston ring issue. On Corollas. On Celicas. On MR2's. Keep feeding it oil and it'll be ok for at least a 2xx,xxx k miles.. Put back a little money every month and by the time the engine craps out you can swap in a 2zz and have a great sports car.

 

You're worried about nothing. If the car's going to burn oil, the primary cause is not going to be because of the cats. Early 1zz's have a known piston ring issue. On Corollas. On Celicas. On MR2's. Keep feeding it oil and it'll be ok for at least a 2xx,xxx k miles.. Put back a little money every month and by the time the engine craps out you can swap in a 2zz and have a great sports car.

Not if the precat material is clogging the main cat.

 

Personally I would back flush the main cat after removing it from the car. More so to reduce backpressure than anything else. The two early 1ZZ cars I have owned both burn oil without having anything to do with the precat (the Corolla did not have a precat). There are many claims of precat causing terminal damage to the 1ZZ after they disintegrate. Do kept a close eye on oil level, some don't and the 1ZZ dies.

 

I cleaned out the main cat with compressed air.

Thanks for everyone's help!!!

 

Did any material come out? Water may have been a better flush material. I would not want to breathe the dust.