Catalytic Converter Problems
Posting Guru
Joined: Mar 2004
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From: Sunapee NH
Just because your state's safety inspection doesn't require emissions testing, doesn't mean you can legally remove emission control devices. Your state's safety inspection may include visual inspection to verify certain devices, such as Cat's, are in place. Heck, some states have been pushing to make after market cat back performance exhaust illegal.
Hope this helps.
Hope this helps.
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New User
Joined: Dec 2009
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Well here is the problem, i changed my plugs my self on my 2006 F 150 5.4 1 of the plugs snapped off in the head, i ended up taking to Ford dealership and they got the broken one out. My truck was still runnoing rough and they advised the pass side cat was no good and was the source of the problem. I want to see if that is in fact the issue by bypassing the cat. I don't want to spend the money on the cat if that is not the problem. Any suggestions. Not much money to spend but have a trruck that i depend on for work and need the cheapest fix available.
Junior User
Joined: Dec 2009
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loosing the cats will only compound your problems. you will throw a ton more codes. the cats are a nessary evil, that the vehicals cant run without. But feel free to remove them and find out. all cars today are made to run with them are removing them will take the vehical out of its element.
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New User
Joined: Dec 2009
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Well, i got the code scan and it is reading P0420, "Catalyst Efficiency Below Threshold Bank 1", any suggestions ?
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Sick 'n Tired
Joined: May 2006
Posts: 2,969
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From: League City, TX
Your dealer saw that same code and just thinks it's easier to replace the cat ($$$) then to actually diagnose the problem. Cat rarely go bad without being caused by an upstream problem...like a stuck injector.
Were there any other codes? Was the P0420 a pending code? Why did you replace the plugs to begin with?
If the cat is truly bad you will get bad hesitation upon heavy acceleration. You might also hear a loud clattering noise like marbles in a can with the hesitation.
I just went through this with my Wife's 5.4L Expedition. They changed both cats, then I changed the plugs...still cat problems on bank 2. Turns out an injector was stuck. So, turns out one stuck injector caused them to have to replace the cat twice.
Were there any other codes? Was the P0420 a pending code? Why did you replace the plugs to begin with?
If the cat is truly bad you will get bad hesitation upon heavy acceleration. You might also hear a loud clattering noise like marbles in a can with the hesitation.
I just went through this with my Wife's 5.4L Expedition. They changed both cats, then I changed the plugs...still cat problems on bank 2. Turns out an injector was stuck. So, turns out one stuck injector caused them to have to replace the cat twice.
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New User
Joined: Dec 2009
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Thanks guys, i actually brought my truck to a friends shop that gave me honest advice. Turns out when i changed the plugs it fixed the upstream problem. The cat is however no good on bank 1. The symptoms you described are dead on " bridge". I am getting the cat changed this weekend. My mech / friend seems to think that this will solve the problems. He has the complete scanning capabilities and did not get any other readings. I will let everyone know how it goes.
Junior User
Joined: Sep 2007
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I'm not seeing how the plug change could be the only problem upstream of a failed cat. I don't doubt that the cat is bad and needs to be replaced but I agree with others here that a rich condition likely led to the failure and, swapping the plugs and replacing the cat will not correct the rich condition. I would still focus attention on the injectors so the new cat does not fail prematurely.
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New User
Joined: Dec 2009
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Well, i am going to pick up my truck this afternoon, new cat installed, then take back to scanner & see if there is any codes. Is it possible that the computer is not picking up a stuck injector or bad coil pack ?
Sick 'n Tired
Joined: May 2006
Posts: 2,969
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From: League City, TX
I'm not seeing how the plug change could be the only problem upstream of a failed cat. I don't doubt that the cat is bad and needs to be replaced but I agree with others here that a rich condition likely led to the failure and, swapping the plugs and replacing the cat will not correct the rich condition. I would still focus attention on the injectors so the new cat does not fail prematurely.
Postmaster
Joined: Jul 2008
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1 bad injector may not show up in a scan. If it does it'll be an air fuel thing. There is a balance test and a couple of other things that can test injectors outlined in the Powertrain and Emissions manual. Most people don't have the capability to check this out at home, but a competent shop can. I would get the injectors tested asap before another cat goes bad.