01-03 3.0 1 less cat than 04+ WHY

[JerZDevil81]

So, I work at NAPA. It looks as if on 04+ there are only 3 cats whereas on my 01 I have 4. Difference being the back pipe has 2 whereas later they only have 1. They both mount the same to the Y and the O2 sensor is in the same place. Has anyone just put the 04+ cat on the 01-03 3.0? It'll save abt $200 (at MY Napa cost) to leave a cat out, plus it'll sound better...


Why on the 01-03 are there 4 and on the 04+ there are only 3?

 

[JerZDevil81]

Oh yea, I do have the aluminum intake manifold.... if that matters for anything... hmmm maybe I should swap...



But I have enough problems as of now...

 

[James86]

My '99 only has 2 cats and an aluminum intake - though not sure what that would have to do with it

 

[JerZDevil81]

Yea, it shouldn't but I know the aluminum intakes are a little more restrictive than the composite.

I'm really just trying to figure out if anyone has used an 04+ on an 01-03 to see if they mount up different. Can't really tell by a picture.

 

[James86]

I believe feelnfroggy did it on his 3.0, but there's more to it than just the intake. the throttle linkage is quite a bit different.

 

[stmitch]

The plastic intakes mount the same as the aluminum ones, but I believe the bolt size is slightly smaller on the composite upper intake.
A ported aluminum intake would probably flow just as well as, or better than, a plastic upper.
Either way would requrie some modding.

 

[JerZDevil81]

any ideas on the cat situation?

 

[stmitch]

Are you certain it's another cat, and not some type of resonator or something? Nothing downstream from the last O2 would be a cat.

They could've changed the number of cats for many reasons. It probably relates to some other change in the trucks like egr not being used anymore, or emissions programming in the PCM changing. It may have just been cheaper to manufacture a different way, or from a different parts supplier too.

If you have emissions testing in your area, I probably wouldn't risk using anything but the cats that were designed for your year. You could probably install the option with fewer cats and not have any issues, because the O2 would still be sending info to the PCM, but it's not a risk I would take if you get tested. If there's no testing where you are, then either option should work.

 

[kimcrwbr1]

It dont matter to a anal retentive smog inspector will write you up if it is not stock. Just rod the 4th one out as long as it is there it will pass the physical inspection. Maybe the O-2 sensor runs on a different set of values as well as the computer . Does the O-2 senser have the same part number between the two systems?

 

[Froggmann]

Here's some info on the composite upper swap I did a couple years ago. Hope it helps: http://www.ranger-forums.com/2-9l-3-0l-v6-tech-32/finally-installed-my-composite-upper-133037/

 

[JerZDevil81]

The thing is on all the aftermarket 04+ Cats I dont see a spot to hookup a downstream O2 sensor. On 01-03 the downstream o2 sensor is between the 2 cats. Walker number for my cat is 52435 and for 04+ its 52431.

01-03

04+

Biggest issue for me is price, the 01-03 pipe is almost double the price of the 04+. Since the downstream 02 is before the 2nd "cat" I don't see what said second cat elimination would do. I know, its illegal to remove cats, however, what is the diference?

 

[adsm08]

In terms of the actual tailpipe emissions there is likely no difference. The second unit is likely a three-way converter, which for a long time were two-bed cats. After a certain point (I don't remember the exact year) the chemistry improved enough that they were able to make reliable and effective single-bed cats, which are always cheaper than two-bed units because it takes a lot less time and material to make them.

A two-bed cat is still considered a single unit though, at least from the perspective of parts catalogs and servicing, so I guess that technically replacing a two-bed with a one-bed wouldn't be removing a cat.

Also it is generally allowable to update an emissions system to be compliant with a later year, which you would be doing. It might even make the tailpipe emissions cleaner to put a later converter in.

 

[JerZDevil81]

Thanks you, exactly what I was looking for. Contemplating compsoite intake swap, egr delete and 04+ exhaust...

I know it'll throw EGR codes, but maybe I'll grab a computer for an 04+....