Catalytic converter

Tiny
JOE HERNER
  • 2001 FORD FOCUS
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 108,000 MILES

What are the symptoms of a catalytic converter going bad? I have a major hesitation on my acceleration. The check engine light is on, and it did put out a P0420 code. Sounds like the catalytic converter then?

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Tuesday, December 14th, 2010 AT 6:21 PM

5 Replies

Tiny
2CARPROS KEN
  • ADMIN
  • 10,929 POSTS

Hello,

Here is a guide that goes into detail of the symptoms of the plugged catalytic converter.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

and here is a guide that will help you test it.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

And this one will give you an idea on what you are in for when replacing a bad cat converter.

https://www.2carpros.com/articles/catalytic-converter-replacement

The diagrams to do the job on your car or (below)

If the your converter is plugged, it will create a restriction in your exhaust system. The buildup of back pressure will cause a drastic drop in engine performance and fuel economy, and may even cause the engine to stall after it starts if the blockage is severe.

Causes of converter failures:

Fouling, clogging, melt-down and breakage of the ceramic substrate inside a converter are common conditions that can cause problems. Plugging is usually the end result of a melt-down, which occurs because the converter gets too hot. This happens because the engine is dumping unburned fuel into the exhaust. The excess fuel lights off inside the converter and sends temperatures soaring. If it gets hot enough, the ceramic substrate that carries the catalyst melts.

The unburned fuel may be getting into the exhaust because of a bad spark plug or valve, but an overly rich air/fuel mixture is another possibility. In older carburetor engines, a heavy or maladjusted carburetor float may be the underlying cause. But on newer engines with "feedback" carbonation or electronic fuel injection, the engine may not be going into "closed loop" (the normal mode where the computer regulates the air/fuel mixture to minimize emissions).

A bad oxygen sensor or coolant sensor may be giving the computer bogus information. A sluggish or dead O2 sensor will make the computer think the exhaust is running lean, so the computer will try to compensate by making the fuel mixture rich. A coolant sensor that always indicates a cold engine will also keep the system in open loop, which means a steady diet of excess fuel. But it might not be the sensor s fault. A thermostat that is stuck open or is too cold for the application can prevent the engine from reaching its normal operating temperature. So if your converter has failed and needs to be replaced, the engine should be diagnosed for any underlying problems before the new converter is installed.

Another cause of converter clogging and contamination is excessive oil consumption. Worn valve guides or seals can allow oil to be sucked into the engine s combustion chambers. The same goes for worn or damaged rings or cylinders. Oil can form a great deal of carbon, and metals present in the oil can contaminate the catalyst. A compression check or leak-down test will tell you if the rings are leaking, while a fluttering vacuum gauge needle will help you identify worn valve guides

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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Monday, July 10th, 2017 AT 5:43 PM
Tiny
HYD23
  • 2002 FORD FOCUS
  • 1.6L
  • AUTOMATIC
  • 100,000 MILES

Hello, My exhaust is blowing loudly I have had it welded once before. Now I have been told that I need a new catalytic converter. However I wanted to ask would it be best for me to order a part online i.E off of Ebay if so what am I searching for exactly I don't want to get the wrong parts. I know someone who can fit it for me. Kind regards Miss Tann

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Monday, July 10th, 2017 AT 5:44 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
  • 20,830 POSTS

No, that would not be a good idea at all. You will not only get the wrong part but probably pay more for it also. Just go to an exhaust specialty shop that does custom exhaust and they have access to aftermarket parts and will install them cheaper and better than you can get it done anywhere else.

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Monday, July 10th, 2017 AT 5:44 PM (Merged)
Tiny
ALY9893
  • 2000 FORD FOCUS
  • 8,000 MILES

My car acts like it doesn't wanna go. Like u press the gas and let off even tho I am not doing so I am keeping the gas pressed and it has a weird smell when it does that. Catalytic converter maybe? It has 8000 miles on motor and 160000 on transmission. We have cleaned the gas tank and checked the vaccum lines. Nothing we've tried has worked

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Monday, July 10th, 2017 AT 5:45 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,227 POSTS

Has the check engine light come on? Have you checked fuel pump pressure to make sure it is within the manufacturer's specs? Have you tried disconnecting the catalytic converter to see if it runs properly?

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Monday, July 10th, 2017 AT 5:45 PM (Merged)

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