sully91rs

91 RS, TBI, dual snorkel intake, no AIR, 123K miles.

Car began rattling at idle every now and then a couple months ago. Sounded like it was coming from the cat. Car ran fine so I didn't worry about it.

Rattling stopped 2 weeks ago, and now the car bogs badly and O2 through ecm reports full rich with anything above quarter throttle.

After doing some reading it seems like cat is clogged. Any supporters?

If it is a clogged cat, is there anything I should checkout/replace when replacing the cat? Like o2 sensor, plugs, etc.?

rocko350

text book case of a clogged cat. o2 sensor should be replaced at 100,000 miles.
but you dont have to. id change the cat, check the o2 cross counts with a scan tool to verify if a new o2 is needed.

slow_90firebird

If your cat is in the process of clogging, take it off the car ASAP and give it the broom handle to knock all the guts out. Then you will be able to worry about purchasing a new one at your leisure, only before your next emissions test. Or if you dont have emissions, then maybe just enjoy the extra power from knocking it out!

sully91rs

UPDATE: Taking this to the Exhaust board.


Any advice on getting it off? Bolts look rusted to death. Should I even bother with them or just cut (grinder or sawzall) them off?

I'm checking out direct fit replacement cats on summit, but they have a couple listed. I'm looking at the Catco 4115 (the cheapest direct fit @ $105)

Any good reason to shell out a couple more dollars for a more expensive one?