1994 Ultra catalytic converter question

[Cntrysthbst]

Got done with the supercharger and started her up. Thought a rod was bad but the noise was coming from the catalytic converter. It's making a metal clunking noise like something is loose and hitting against something. The engine sputters at idle and when giving it gas. Doesn't die.

X-file #1! I was listening to it underneath and sure enough I heard a small piece of metal rattle through the exhaust all the way to the muffler, when it got to the muffer it dropped inside of it. No more rattle but engine is still sputtering. Will a bad catalytic converter cause the sputtering? And I would have to say the catalytic converter needs replaced, right?

Bout 145,000 miles on it. No codes. Just reconnected the battery anyway. Thanks

[DioGreer]

chances are the cat is toast. You can either get all the crap out of it and potentially fail emissions (may not be a problem depending on where you live) or replace it.

they can go bad. Back when I drove an 86 olds cutlass supreme, I got the cat cleaned out when I did an engine swap. only passed emissions because the testing machine was screwed!

[Loekee75]

I just had my cat replaced at 147,876 miles in my 92'
It had a leak that would cause a noticeable humming noise during accellaration. There was also a bad exhaust smell from it.

[Cntrysthbst]

The catalytic converter is welded. I've heard about 4 pieces go through the exhaust and drop in the muffler. Did it sputter at idle like it was choking? Just wondering cause there's other things that can make the engine run like that too. Just want to be sure.

[Alibi]

Yeah, I second a new cat converter. I would opt for a new high-flow converter over gutting the cat, generally because I have experience MPG loss from gutted cats. The only really good way to replace it is to take it to a muffler shop and let them chop off the old one and weld in the new one....Unless you have a sawzall and are a good welder

A plugged converter would create too much backpressure on the engine, resulting in the sputtering that you are getting. In any case, at 140 some odd thousand miles you should probably get a new cat anyway. A plugged cat wouldn't throw codes either since there isn't a secondary O2 sensor after the cat.

[Cntrysthbst]

I searched alittle and someone said something about starting your car a night and see if your cats glowing, is that true?

Can you have a bad running engine and lack of power with a bad cat?

[Cntrysthbst]

Do I have to use an OBD II catalytic converter? I have the OBD II hookup but believe the system is still OBD I. Will a universal one work? Thanks

[Alibi]

Any aftermarket cat ought to work since you don't have a second O2 sensor behind the Cat to measure airflow after the cat. Watching the cat go cherry (turn red from heat) only works if the cat is very plugged. The restriction of air and heat causes the cat to heat up high enough to glow.

[Cntrysthbst]

ohrightythen, thanks for your help!!