Hey guys, two part question:

I think I might have a clogged cat...car ran really bad for long time with previous owner...lots of problem...got it running much better but still not good...runs good just sitting there...small hesitation when I wap the throttle but under load it is a dog...no power...so I tried to pull Y pipe off cat with no luck so I heard just pulling the O2 will give the exhaust enough relief to tell if cat is clogged...did not sound right but I tried...no noticeable difference

So to the questions:

Will pulling the O2 sensor make a difference if the cat is clogged?

If not any tips on getting cat off? I tried cold and hot...was think of getting hot then trying to cool Y pipe to help break free.

Thanks for input.

 

Sounds like a Cat
Is it extremely HOT(the cat)?

Part 1- Pull the O2 will make a difference, just don't go anywhere. You will know right away
Part-2 Just soak/spray converter with some good spray like blaster or equivilant and let soak, don't rush it, then remove bolts.

 

Ok well I pulled O2 and it ran the same so maybe not cat...back to intake I guess...maybe clogged injectors

 

I'm assuming you went threw the ignition first? A neglected car's ignition is usually one of the first sources of problems. Your problem does not sound like a cat to me as you can still rev the motor in park but it still would not hurt to check. Using a torch to heat the front should take it right off. While its off and providing it is original, take it to the scrapyard for $95 and buy a new replacement.

 

You can easily test the exhaust (and the cat) for restriction with a vacuum gauge, and you may also find the low power output issue. Connect the gauge to any full vacuum port on the intake. With the engine at idle, the vacuum should be at a stable 20 inches or so. Rev the vehicle to 4000 rpm and observe the guage as you do so. It should drop to almost zero then begin to climb again. If the exhaust is clogged, vacuum at idle may be lower (15 or so) and as soon as you rev the engine the vacuum will drop to zero and stay there until left at idle for a few seconds or more.

 

I don't know exactly what car you are working on. But IF it has an EGR system I would suggest checking for correct operation.