Second Catalytic Converter?

gatornek

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Come to learn on another thread, that these 2.0s have 2 cats?? One 'smallish' one on the downpipe, where I imagine the O2 sensor is plugged in and reading the EFR? And a larger one right after, that looks like it does the majority of the scrubbing?

Can someone elaborate why they chose this design, rather than just one large catalytic converter? This is new to me.

Also, what an awful restriction downpipe looks to be. I mean, it really poo-poo's my desire to tune my 2.0. No wonder the Mavericks have all this stuff available in the aftermarket.

Ford Bronco Sport Second Catalytic Converter? 1718208132008-tr
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mwangarch

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2 cats is a very common design. Upstream and downstream. My 2000 Boxster had 4, lol.
 
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gatornek

gatornek

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2 cats is a very common design. Upstream and downstream. My 2000 Boxster had 4, lol.
Maybe "very common" is a bit strong. But I agree that I shouldn't have been as flabberglasted as I was. Been trying to read up since yesterday as the reasoning behind it, and its a bit vague. All I've really been able to turn up is 'better emissions control'.

But seeing as how these pieces are so expensive, I wonder how much of it has to do with maybe driving up the price of the engine, and thus, the vehicle.
 

Dude

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On Bronco Sports (at least for 2.0L engine)…

Primary cat has an O2 sensor, the secondary cat does not have an O2 sensor.

The secondary catalytic converter reduces emissions during the start up phase before the primary cat gets to temperature (cold cats are not as effective as hot cats).

Typically a primary cat cleans up HC HydroCarbon and CO Carbon Monoxide emissions, the secondary cat cleans up NOx Nitrogen Oxide emissions.

Nitrogen is trapped within the converter while oxygen passes through. The oxidation catalyst is the second catalytic event. It reduces unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over the metal catalyst.
 


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gatornek

gatornek

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The secondary catalytic converter reduces emissions during the start up phase before the primary cat gets to temperature (cold cats are not as effective as hot cats).
Yep. This describes all cats. So my followup would be 'what is it about the secondary cat that makes it so effective without getting up to temp?

Typically a primary cat cleans up HC HydroCarbon and CO Carbon Monoxide emissions, the secondary cat cleans up NOx Nitrogen Oxide emissions.
Typically? Typically, this is both done in one cat.

Nitrogen is trapped within the converter while oxygen passes through. The oxidation catalyst is the second catalytic event. It reduces unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over the metal catalyst.
Basic cat operation. Does not help me with the reasoning to break something into multiple pieces that has historically been done in one. And again, the only thing that makes sense is having better granular control of that emissions process, while also making the exhaust much more expensive.
 

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Yep. This describes all cats. So my followup would be 'what is it about the secondary cat that makes it so effective without getting up to temp?


Typically? Typically, this is both done in one cat.


Basic cat operation. Does not help me with the reasoning to break something into multiple pieces that has historically been done in one. And again, the only thing that makes sense is having better granular control of that emissions process, while also making the exhaust much more expensive.
There are different metals (combinations of metals and quantities) used in a multiple cat design and each cat has its purpose. What you are pointing out is we do not know the Ford design spec for each cat used on Bronco Sports.

it’s an interesting topic and question. My local muffler shop is contacting the cat manufacturer and is also locating the prices for each cat so when I stop in I’ll see if they can shed any light or provide a link to each of the cat’s spec.

I’ll post if I can get the technical details.


all this link shows is there are different part numbers (and prices) for each cat but my searches online did not yield any useful technical info (most of my searches were in 2023 timeframe)

https://parts.lakelandford.com/a/Ford__Bronco-Sport/__9232949/Exhaust-system-Exhaust-components/BS21310.html
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