I have a 2001 LS1 Firebird Formula 6 speed which just started acting up today. The car is pretty much stock (flowmasters being the only mod so far), the car has 120,000 miles and has a check engine light for catalytic converter below peak efficiency. This light has been on for two months and the car has always run great, until today.... I was driving the car around town and as soon as the car got up to normal operating temp (195 ish), the car did not want to rev over 3000 rpm and hesitated and began bogging out while attempting to pull away from a dead stop. The idle dropped to 4-500 rpms and I limped the car home. I did notice what looked like a little smoke coming from the front of the intake manifold/throttle body area. I started the car 2-3 hours later once it cooled off and it ran like a champ! Until it got hot again... Than it happenned again, and again I limped the car home. I'm going to put the car on a scanner in the morning and see if it is throwing any new codes. Any help would be very much appreciated.

 

check your front o2 sensors

 

This would most likely be your cat. stopped up at this point.

 

Would either the o2 sensor being bad or the stopped up cat cause this problem only once the engine reaches full operating temp?

 

The cat code that you have does not directly indicate a clogged cat at all, but rather a cat that is not scrubbing the exhaust well enough. Sometimes that code will be tripped continously with a high flow cat, since the post cat O2 readings will respond too quickly.

On the other hand, the cat may be clogged for other reasons (melted material inside the cat no longer passing exhaust), or the issue may be totally unrelated. If you have an IR gun, you can check cat temp to see how it compares to the other bank (cat temp should be between 450-600°F, depending on where you take the temp).

Or, the issue may have nothing to do with the cat(s) at all. A fuel related problem (low pressure, lean mixture) can also create the issues you have described.