a little OT (catalytic converter)

55 50 Ron · Jun 15, 2017

When an automobile catalytic converter is failing, do you know it's failing and how do you know? What are actions or re-actions that are noticeable? Thanks Ron

Mike M · Jun 15, 2017

On my 1996 dodge truck it started rattling.

Others can plug and you loose power. I can remember at the dealership the one tech tested one by unhooking the exhaust pipe from the engine and running up the alley next to the building. That buick V6 never sounded better ! LOL.
They make a flow meter you can put in place of the o2 sensors to test for restriction on them too.

Patsdeere · Jun 15, 2017

My 97 Toyota throws a code. 99% of the time the code means plugged cat.

macec3(TX) · Jun 15, 2017

I had a Dodge company truck about 14 years ago. It started running very rough. Sluggish and no power. The farther I drove it the worse it ran. Barely made it to the dealer. They said the catalytic converter was plugged. Replaced it.

tomturkey · Jun 15, 2017

I think Mike has it,Grandsons 01 Chevy S-10 started running poorly, real sluggish, would try to get speed and rpm up if you stomped on it but just did not react. After chasing my tail thru the ignition system and not accomplishing anything. I dropped the exhaust pipes from the manifolds. OH MY, what a difference. plugged up cats (two). Your gonna get codes for o2 sensors, misfires left or right bank, might even get a crank sensor code. Drop the exhaust pipe and give it a go. gobble

David G · Jun 15, 2017

I would assume you could pull the O2 sensor and check back pressure to see if it is plugging, would need to check for CO level to see if it is functioning correctly.

rustred · Jun 15, 2017

on my duramax i could tell by the strong weird stinky exhaust smell it was plugged. removed and replaced with a piece of pipe in its place. had more power than before also.

jtwat · Jun 15, 2017

The vehicles computer looks at the signals from the upstream vs downstream oxygen sensors. If the the signals are out of range the computer will set a code. This is when the converter is worn out. A convertor can also come apart inside and you will hear it rattle. Both problems require a converter replacement.
If you need a replacement, go to a exhaust shop, not Dealer. Will be a lot cheaper. Around $200 where I live.

GregCO · Jun 15, 2017

Generally the hydrocarbons will be high during an emissions test if you are required to get one done and it is failing. the other thing is if you take it out and give it a good run, pull over and use a IR thermometer and take a temp just ahead of the cat and one behind it, the one behind it should be hotter. If they are the same it is not working.

Greg

Steven-Id · Jun 15, 2017

They say you should not have more than about 1-2 psi pressure in the exhaust. You can drill a hole in front of the cat and put a pressure guage in it and see what pressure you have. If it is high drill a hole behind the cat and check. If it is low the cat is plugged. If it is still high it could be a plug farther down the exhaust. On my daughters Grand Am I drilled a hole and put my fuel pump pressure guage up to it and had her start the car and it immediately pegged the needle at 10 psi. I unhooked the exhaust and my what a difference.

Steven

jimg.allentown · Jun 15, 2017

Really need more information to answer your question intelligently.
What year of a car are you referring to?
Why would you suspect a failing catalytic converter?

Here is a somewhat generic answer:
If the cat is losing its efficiency, and is not doing its job well, it may be contaminated or just worn out.
If there is a restriction in the exhaust, there will be a loss of power most noticeably under heavy load and/or high RPMs.
If the vehicle is 1995 or older, you can ignore the problem unless the cat is plugged or you are in an enhanced emission inspection location.
If the vehicle is 1996 or newer, a failed or failing cat will generate a code in the P0420 to p0430 range.

a little OT (catalytic converter)

55 50 Ron

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Mike M

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Patsdeere

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macec3(TX)

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tomturkey

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David G

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rustred

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jtwat

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GregCO

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Steven-Id

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jimg.allentown

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