how to tell if cat is clogged?

[southkurtk]

I took the cat off my 87 shelby z today that seemed to be the original one. And it Didnt seem to be clogged. I could see right thru it and didnt seem to be any heavier than it should be. So my question is how can you tell. Cuz ill tell you what it made the world of a difference taking it off. The car now boost fully which i could get 10psi max before. And more quickly as well. plug just seems to run better overall.

[BadAssPerformance]

Plugged they wont rev out, will run hot, maybe leak at teh donut gasket if really plugged.

Just cuz you can see thru it doesnt mean its not junk. If it is carboned up so the tiny tubes are slightly restricted then they will flow a bunch less...

[turbovanman²]

I took the cat off my 87 shelby z today that seemed to be the original one. And it Didnt seem to be clogged. I could see right thru it and didnt seem to be any heavier than it should be. So my question is how can you tell. Cuz ill tell you what it made the world of a difference taking it off. The car now boost fully which i could get 10psi max before. And more quickly as well. plug just seems to run better overall.

Stock cats and most aftermarket units are a huge restriction, so removing one can show nice gains.

Yours is still probably ok but as you found out, letting the exhaust breath on a turbo motor makes a world of difference, imagine a nice 2.5 or 3 inch mandrel bent system with a good muffler? :thumb:

[Darkapollo]

feed it a lot of fiber, just be prepaired for the mess!

[karlak]

feed it a lot of fiber, just be prepaired for the mess!

Fur Balls :nod:

[southkurtk]

kool thanks for the responses yeah i nice full 2.5 full exhaust is coming soon. No bigger as this is gonna be a daily and i dont want it to loud. 2.5 straight pipe.

[Dusty_Duster]

If a catalytic converter is functioning correctly, the temperature of the exhaust exiting the cat should be slightly warmer than the exhaust entering the cat. This can be verified with an infrared thermometer.

If the exhaust leaving the cat is the same temperature or cooler, the cat is not functioning properly and may be clogged.

[LynX853]

or take off your o2 sensor and just run the open hole. if it makes a noticible differance then its prob a clogged cat. but from what you are describing I thing you just found out how crappy the stock system is

[jory]

My daytona had a clogged cat when I bought it. It would accelerate fine at part throttle but steady cruising would make it buck and choke. It would only rev to like 3500 if I floored it. When I took the exhaust off black soot and chunks fell out of the cat.

[southkurtk]

good info thanks