dual catalytic converters?

[LearjetMinako]

So whats the deal with multi-cat converters. Is Ford putting 2x for each bank of cylinders, and each cat converter scrub for a certian emission (1x for HC & CO, the other for NOx)?

 

[Original_Ranger84]

I take cats with me everytime I jog just in case I need a snack.

I prefer squirrels... a little nutty but you can carry more so you can spread out your snacks better.

 

[adsm08]

So whats the deal with multi-cat converters. Is Ford putting 2x for each bank of cylinders, and each cat converter scrub for a certian emission (1x for HC & CO, the other for NOx)?

Kinda. The upstream (monitored) catalyst is usually a three-way bed that converts NoX, HC, and CO. The down stream (unmonitored) is usually only a two-way that only does NoX and CO.

It sucks trying to use emissions labels to figure out which one you are supposed to have because both get abbreviated TWC, so I usually go with a three way if I'm putting in a direct fit.

 

[LearjetMinako]

So generaly the first cat-converter takes care of the big three emissions (CO, HC, & NOx) and the cat-converter afterwards is to further reduce what the first one missed. Damn, I would hate to replace all 4x cats at the same time. I almost replaced mine at one point till I found out how much they cost just for one!!! Gotta love trouble codes, "Catalysis effiiency below threshold", so one would surely suspect the catalysis converter. Luckily, it was a O2s going out and just needed to be replaced. Live readouts help todetermine problems sometimes.

 

[85_Ranger4x4]

So whats the deal with multi-cat converters. Is Ford putting 2x for each bank of cylinders, and each cat converter scrub for a certian emission (1x for HC & CO, the other for NOx)?

They work better closer to the engine (for heat), and one bank has to dodge the drivetrain to join the other bank and has time to cool otherwise.

Even if you have one cat there is still two partitions in it that operate the same way as a modern 2 cat system.

Also at least on my '150 I think having them somewhat tucked up between the engine and frame they are less likely to start grass fires than under the floorboard.

 

[baxtej44]

not trying to hijack...

but a side question:

88 xlt 2.9L 4x4 stock... has the dual cats, as far as i'm aware in Nebraska we don't have any emissions to pass, at least i've never had to get tested or anything... could i replace with a single? would/could it harm my engine? would/could it harm the environment more? we are looking at a 23 year old cat system....

 

[straycat]

More blah back at ya!!!!! lol I care about my world.....we only have a short time on it, why not take care better care of it? I grew up in Africa, Germany and Brazil, Thailand in the 60's and 70's. I got to go visit my old stomping grounds again while in Special Ops and saw some really big changes to Germany and Brazil. Thailand has changed into a pollution sewer!! Kenya still looks the same and the land looks the same. I went back last year and it is still beautiful over there. At least some countries are trying to save the planet!!!

 

[doorgunner]

Awwwwwwwwwwwwwwwwwwwwwwwwww....contrare...(pardon my french)...........but cats Do have something to do with noise reduction!

However, I have learned on this Site that cats are good for our lungs & for mpg's on newer vehicles (as much as I despise cats--metal or meaty).

My Ranger has a brand new cat on each exhaust pipe......NO MUFFLERS...(those shiny things sticking out the back of the truck are just the casings of Harley Davidson mufflers)....just cats.....and it's not any louder than one of the Factory high performance Mustangs...


Cats are good.......now excuse me while i go wash my mouth out with soap...

 

[adsm08]

not trying to hijack...

but a side question:

88 xlt 2.9L 4x4 stock... has the dual cats, as far as i'm aware in Nebraska we don't have any emissions to pass, at least i've never had to get tested or anything... could i replace with a single? would/could it harm my engine? would/could it harm the environment more? we are looking at a 23 year old cat system....

If you buy a three-way catalyst it will be about the same as what you have now.

It is a 3-way cat, just in two beds. One does Nox and CO, and one does HC.

 

[shane96ranger]

If you buy a three-way catalyst it will be about the same as what you have now.

It is a 3-way cat, just in two beds. One does Nox and CD, and one does HC.

This ↑

I don't think the 3 ways last as long (in my experience), but they are much cheaper than going with OEM style.

 

[adsm08]

This ↑

I don't think the 3 ways last as long (in my experience), but they are much cheaper than going with OEM style.

I think you are thinking direct fit vs universal fit.

Three way cats have been common for years now in both direct fit and universal fit and as original equipment.

 

[shane96ranger]

I think you are thinking direct fit vs universal fit.

Three way cats have been common for years now in both direct fit and universal fit and as original equipment.

Yes, I am talking about my experience with Universal units. Sorry for the confusion.

EDIT: I assumed you were too....my bad!

 

[GoodOld85BlueBalls]

Ok I will take a few moment to explain this how I understand it as I work as an Emissions Tec in the oil and gas industry. There are three types of catalyst. The first is the NSCR catalyst (three way) or Non Selective Catalyst Reduction, It is for a Rich Burn engine only (or Stoicometric). The NSCR Catalyst goes after reduction of Carbon Monoxide, Nitric Oxide, Nitrogen Dioxide, Formaldehydes and VOC emissions. A NSCR catalyst requires very little left over Oxygen in the exhaust to work, somewhere around .4% to operate correctly, that is why when there is a misfire it tends to get very hot as there is unburned fuel and AIR from the missing cylinder that creates a Exothermic reaction in the catalyst as it burned.

There is always some Carbon Monoxide left over and that is where the second type of catalyst comes in to play. The second type is called an Oxidation catalyst as it goes primarily after reducing Carbon Monoxide and Formaldehydes. It is also called a lean burn catalyst as it requires about 10 to 15% Oxygen in the exhaust stream for it to operate. That is usually the second catalyst in a housing or exhaust system and that is why the air pump on the engine blows into the middle of the catalyst housing. To get the air in there to help with the oxidation reaction (rust). It is also a exothermic reaction, but it will not run wild when there is a misfire in the engine.

The last type of catalyst is called the SCR, or Selective Catalyst Reduction. It is a type of catalyst that requires a catalyst or burning agent. This agent is known as Urea (Ammonia) and is injected into the exhaust stream before the catalyst. This catalyst goes after NOx (Nitrogen dioxide and Nitric Oxide). You see these primarily on the new Diesel trucks out there now as the combustion process has a very high temperature and high peak firing pressure. High temperature creates high levels of NOx and a diesel engine puts out a lot of it.

There are some combination units out there at the moment that use all three of these catalyst in line, but the NSCR (three way) is always in line first, then the Oxidization and often on industrial engines followed by the SCR catalyst.

22 years I have been working with this crap, assuring compliance with federal and state agencies. And it always pisses me off when people want to remove it from their vehicles. It is just plain wrong to remove it.

 

[Toms01PSD]

And it always pisses me off when people want to remove it from their vehicles. It is just plain wrong to remove it.

Hmm, wonder why? I've read plenty about people removing the emissions shit from road tractors and other diesels because it kills them.

 

[RustedRanger]

+1 doorgunner.