How to 100% determine that I have a clogged cat?

[RangerReviver1990]

Hey, back again with yet another question. My dad and I are bouncing ideas around on why my truck is a little on the underpowered side. It used to run fine for a bone stock 35 year old engine, but lately it’s been hit or miss. It’s either taking it out of gear and the truck rpm’s shoot up, almost like it’s trying to keeps its self from stalling out. Or it feels like I’m towing a trailer and it’s just bogging itself down. My dad said something might be clogged, like my rear catalytic converter has finally got clogged up or something. I feel like it’s multiple things contributing to robbed engine power, or it could just all be my clogged cats. Idek at this point

 

[superj]

unbolt the exhaust ahead of the cat and see if the problem goes away.

and the temp sensor is not telling the computer its hot. the computer will raise the rpms to help cooling if it thinks the truck is overheating.

 

[RangerReviver1990]

unbolt the exhaust ahead of the cat and see if the problem goes away.

and the temp sensor is not telling the computer its hot. the computer will raise the rpms to help cooling if it thinks the truck is overheating.

Jesus…that’s gonna be fun to remove. And the truck raising RPMs because it thinks it’s overheating actually makes sense

 

[Uncle Gump]

I've never heard of ECM raising RPM on a hot engine. It actually defeats the purpose... the faster it runs the more heat it makes.

Google vacuum testing for a restricted exhaust.

 

[alwaysFlOoReD]

Second on vacuum testing.

 

[superj]

lots of vehicles do that rpm deal but lots don't, also. its just something to check.

some vehicles will hunt, too, when getting hot, to help cool. moves coolant more, i guess

 

[SenorNoob]

The only 100% way would be to remove it and look thru, but a vacuum gauge is probably a close (think 90%) second.