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Discussion Starter #1
We just had our "service engine soon" light come on. After taking it in to be checked we were told that our catalytic converter is going bad.
We have a 2003 V8 explorer.
Is this something we can wait on a bit. What are the signs that its time to et changed. We were a bit shocked to hear the price on this:yikes:
Thanks
 

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How many miles on the vehicle ? Federal emission warranty is 8 years 80k miles.I would clear the codes and see if they return.You may have a problem getting a safety inspection sticker depending on your location.
 

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the mileage would be something to factor in. i have an 89 LTD crown victoria with the original cats, and they're still fine. the O2 sensor(s) might be a problem too... converters rarely go bad, and usually would last longer than the vehicle, unless there was a design flaw...
 

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We just had our "service engine soon" light come on. After taking it in to be checked we were told that our catalytic converter is going bad.
We have a 2003 V8 explorer.
Is this something we can wait on a bit. What are the signs that its time to et changed. We were a bit shocked to hear the price on this:yikes:
Thanks
If it's running OK then at least the cat is not plugged...this would cause engine damage.
Get a second opinion or ask them how they came to that conclusion.....code numbers!
 

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easiest way to tell if the cat is plugged, is it backfiring? if dual cats, is one side of engine hotter than the other?
 

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Discussion Starter #6
I think they went by what the codes told them.
The truck itself has 102,000, but we just had a newer engine put in 2 weeks ago.
This place is a Ford dealership where we bought it from. We have had this thing only since Jan 2010 and we have had it in 8 times for repairs, very frustrating!
2 wheel bearings, rear end diff, major oil leak, heat went out.
Heat went out right before we blew the engine.
NOW could all this with the engine be from a bad cat?
 

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maybe ... simple way to fix cat, take chunk of exhaust pipe, drive through cat ... tell no one. :devil:
 

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unless they're like the cats on my 89 crown vic, where they were quieter than the mufflers, then you won't have to tell anyone, they'll hear it...
 

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I think they went by what the codes told them.
The truck itself has 102,000, but we just had a newer engine put in 2 weeks ago.
This place is a Ford dealership where we bought it from. We have had this thing only since Jan 2010 and we have had it in 8 times for repairs, very frustrating!
2 wheel bearings, rear end diff, major oil leak, heat went out.
Heat went out right before we blew the engine.
NOW could all this with the engine be from a bad cat
?
Sounds like a head gasket popped. This may have ruined the cats, overheated or coolant pushed through them.
 

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I would think that the engine killed the cats. Did they reset the codes? And if so, did the check engine light come back on. Was the codes for Ineffecient cats? That means that the signal from the cat swings just as fast as the Hego sensor. It shouldn't. The Hego sensor swings across midline (.5 Volts) 8 times in 10 seconds under normal operation, the Cat monitor stays high or low for a period of time, up to 2 minutes, before it switches. This is due to the release of oxygen from the bed of the cat. I would guess that you would have to drive the vehicle with a monitor in it to see if the cat was the problem or the sensor. If the sensor never switches, you will get the same code as if the cat was defective,even though the sensor is the problem, if it switches as often as the O2 sensor, then the cat is the problem.
 

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Good thread guys!

Just to be clear, the HEGO is the front O2 sensor, or pre cat.
The Cat Monitor is the rear O2 sensor, or post cat.

Did I get that right?

And how does a cat "store oxygen" anyway?
 

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Most modern cars are equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce - carbon monoxide, unburnt hydrocarbons and nitrogen oxide molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidization catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of the catalyst to the exhaust stream, while also minimising the amount of catalyst required (they are very expensive).
There are three main types of structures used in catalytic converters - ceramic honeycomb, metal plate and ceramic beads (now almost obsolete) - Ford like most cars today use a ceramic honeycomb structure.

The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the nitrogen oxide emissions. When such molecules come in contact with the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2.

The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas.
The third stage is a control system that monitors the exhaust stream, and uses this information to control the fuel injection system. There is a heated oxygen sensor (also called a Lambda Sensor) mounted upstream of the catalytic converter, meaning it is closer to the engine than the converter. This sensor tells the PCM how much oxygen is in the exhaust. The PMC can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the PCM to ensure that the engine is running at close to the stoichiometric point, while also making sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and carbon monoxide
 

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...Was the codes for Inefficient cats? That means that the signal from the cat swings just as fast as the Hego sensor. It shouldn't. The Hego sensor swings across midline (.5 Volts) 8 times in 10 seconds under normal operation, the Cat monitor stays high or low for a period of time, up to 2 minutes, before it switches. This is due to the release of oxygen from the bed of the cat....
Here is a helpful illustration...

 
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