when they are clogged up
smells like a rotten egg
they turn cherry red when hot
the engine sound the same as when the spark plugs are fouled by excess gasoline dumped in the piston chambers.
pull it out and look toward a bright light through the cat hole, the lesser light you see the higher concentration of crap is inside of it, which = time to replace. but at 150 i would replace anyways
'90 CRX DX_5sp
"Maybe it's better that way... memories can be terribly painful, being able to forget is a great blessing"