How many cats?

[engine]

My local muffler shop said my Ranger had four catalytic converters where he expected two. I was in for a muffler for my 2002 Ranger SOHC 4wd. What could he have been talking about?

 

[scotts90ranger]

The number of cats wanders over the years... sometimes they use some coarse cats mainly to burn off hydrocarbons first in line then a larger finer cat behind that to convert NOX and CO, and with more horsepower they went with dual exhaust before the muffler so 4 cats for less resistance...

 

[RonD]

They may use 1 cat on each side of "Y" pipe, then 2 cats on main pipe

Engineering wise there is an emissions standard for each engine model/vehicle each year
Two larger Cats may work
Or 4 smaller cats may fit better and be cheaper when buying in quantity
You may also get better performance from 4 smaller cats, better flow thru

 

[DILLARD000]

Suspect your 2002 V6~4.0L~SOHC has same exhaust arrangement as my 2001 with 4 CatCons & 3 OxSensors, pic below.
Click here for more info on this ExhaustSystem.

 

[engine]

Many thanks. Great diagram. I had no idea. I guess this shows how old I am.

 

[Bill]

I have three cats. They eat a lot and stink up the house when they use the litter box.

 

[ekrampitzjr]

I have three cats. They eat a lot and stink up the house when they use the litter box.

You beat me to it. I was going to mention my two Siamese mixes. Snowy and Buddy say hi to everyone on the forum.

 

[DILLARD000]

Could make an off color joke here, but Ill just let that thought simmer.

 

[Chapap]

Huh... I thought 1 cat per bank and 2 O2 sensors per cat was the pinnacle of emissions. That thing effectively has 3 cats per bank . Do vehicles exist with true dual exhaust and 6 cats?

 

[sgtsandman]

Mine has two Catalytic converters. One on each bank. Maybe it has something to do with the emissions standard it was built to meet?

 

[lil_Blue_Ford]

It seems to vary widely. My F-150 had two big cats. When I suspected one or both was bad and took it to an exhaust shop, it left the shop with one cat. I didn’t argue. I did ask and they pretty much told me don’t worry, it will be fine.

I’ve also been told that the small cats on they down pipes are not true cats but pre-cats.

All I know is that if there was a cat on the exhaust from the factory, Federal law says there should always be a cat on the exhaust. Some newer vehicles are more sensitive to exhaust changes than older ones and some cats are stupid expensive. My junk is old enough that it gets a universal high flow cat when it has to be replaced.

 

[4x4prepper]

> Do vehicles exist with true dual exhaust and 6 cats?

Never seen six, but, a 2005 Land Rover has (2) cats and (2) O2 sensors each bank. Just doubled check to be sure.

 

[scotts90ranger]

the 5.0L explorers have 4 cats and 4 oxygen sensors, are dual exhaust until the muffler (two in one out muffler) then a resonator over the axle... it's a mess under there...

 

[JohnnyO]

I’ve also been told that the small cats on they down pipes are not true cats but pre-cats.

Exactly. Cats don't function fully until they're warmed up. The pre-cats are smaller and close to the engine so they clean the exhaust until the main cat(s) is warmed up.
Had to get a new Y-pipe with cats for my old Sport Trac when it hit about 180,000 miles. The CEL wouldn't stay off long enough to pass the annual emissions inspection. New cat Y-pipe cost over $800. The main cat farther back was still okay.

 

[cbxer55]

One kitty kat is one kitty kat too many.