Plugged catalytic converter?????

original.

Unless the engine has run rich in a very poor tune for a long while it is very unlikley it is pluged. You could remove O2 sensor and test pressure with proper gage and if it is 6 to 8 psi tops it is okay. If it is plugged, it will be a lot higher. I am thinking fuel quality here and the stuttering is being cause by erratic timing by ECM try to control fuel knock. (when you hear it it is because it is beyond the ECM?s ability to control. Try some better fuel with new plugs, wires, cap and rotor and see how it runs.

Had the same problem with my 2001 Impala 3.4, at 100K miles. Became very hard to climb the hills around here. Felt like the tranny wasn't shifting or something; high rpm's but no power. Tranny shop said that was not the problem; muffler shop down the road changed the cat converter. The converter was clogged with carbon, and there were some flecks of metal (??) on the inlet screen. Never found a good explanation for that one. It has run 36,000 miles since.

Only way I know to check it is to take it off and look. Yeah, it's a pain.

-= Larry A.

Thought you could test them with an IR thermometer???

Al

The correct method would be to install a pressure gauge in place of the front O2 sensor, start the engine and take a reading. Anything over 3psi is cause for suspicion.

The O2 threads are the same as an 18mm spark plug, so one can either fabricate an adaptor from an old spark plug (F9Y) or use an 18mm adaptor from a compresion tester. The rest is done with a compound vacuum/pressure gauge.

Thanks aarcuda,I was thinking there was a way to check via the o2 senser outlet...will suggest it to my mechanic although I think he is probably right on replacing it.He has never steered me wrong yet and he is a good friend,just wanted to double check cuz money is tight now.

pull the pre-cat O2 sensors and see if it runs better...............

I would double check because bad/low octane gas in hot weather can cause a severe power loss in some newer engines.