Questions about Catylitic Converters

[tgrubbe]

I have been looking for a while for an answer to this question, and can find it nowhere. As most people on here know, there are usually, (or at least on all the ones I have seen), four cats on the explorer. The two a couple feet after the headers and two a couple feet further. The two furthest from the engine on mine are rusting out and I need to replace them to stop some huge exhaust leak, and currently I cannot afford to buy new ones. So is it legal to put pipes through those since I already have the two others? And can it effect the engine performance with the O2 sensors? I want to be sure this is ok to do before I try it, Thanks! And as for legality, I am located in Missouri.

 

[mrboyle]

Federal law states that it is illegal. If you live anywhere that requires emissions testing, it will likely fail the tests as the two cats serve a different purpose. The first cat generally a reduction catalysts which cause NOx to be reduced into O2 and N2. The second cat is an oxidation catalyst which causes HC and CO to oxidize with any available oxygen into CO2 + H20. If you were to "bypass" the rear cats you would likely fail the required emissions tests. Now, say you are in an area that doesn't require emissions testing, you will still likely cause the ECU to turn on the check engine light as the rear O2 sensors would not be seeing a proper O2 level variation between the primary and secondary O2 sensors. There are ways around this by using O2 simulators and such, but in all honesty, you are better off saving your pennies and replacing the cats.
One way to save some money on replacement cats is to keep an eye out for someone parting out a similar explorer. You will have to go through a private party to get used cats as it is illegal for shops or wrecking yards to sell them used.

 

[rizzjc]

Pretty sure the 6-cylinder and 8-cylinder are no different, but there is no O2 sensor AFTER the second pair of cats. There are only sensors before and after the first pair of cats, so there would be no CEL caused by removing the secondary cats.

 

[DjDom]

Pretty sure the 6-cylinder and 8-cylinder are no different, but there is no O2 sensor AFTER the second pair of cats. There are only sensors before and after the first pair of cats, so there would be no CEL caused by removing the secondary cats.

This is correct, there's only a sensor before the second pair of cats.
So it wouldn't cause any problems with O2 sensors, but it would make you fail emission tests..

 

[tgrubbe]

Thanks, Those were the answers I was looking for. And as for finding replacement ones, is there any way I can tell by looking at the catalyst on the inside of the entire unit to see if it is still good or if they are all clogged up?

 

[Campoli]

Just cut them off and take to scrap yard you'll make a quick $80-$120
If you live in a state that requires emissions testing just slowly save up and right before your X is due for inspection buy one online if its the dual rear cat you can buy a cheap a$$ one and you'll pass emissions
I've noticed there are many many many ppl on here that go all legal when you talk about cuttin cats but then here they are tearin a$$ through the woods lmfao

Good luck w the exhaust dude

 

[OffTrac]

I've noticed there are many many many ppl on here that go all legal when you talk about cuttin cats but then here they are tearin a$$ through the woods lmfao

Legally. I've seen people on here get torn apart for bragging about trespassing.

 

[Campoli]

Legally. I've seen people on here get torn apart for bragging about trespassing.

Hilarious always ask be for you ride rule #1

 

[tgrubbe]

Thanks for all the help, and even though my state doesn't have emissions checks and I cant stand the exhaust fumes in my car, I may just buy new ones.

 

[Turdle]

I thought Missouri ( KC metro) had inspections annually.

Yes, yes they do. You will probably be failed for no rear cats.


http://www.mshp.dps.missouri.gov/MSHPWeb/PatrolDivisions/MVI/documents/MVIRegulationsManual.pdf

 

[CDW6212R]

Do not the better state inspections look for just one cat per bank? That is all that is needed, and most aftermarket cats will achieve testing limits, for when that is what is important.

If it passes a sniffer test, it should be legal.

 

[tgrubbe]

We do have inspections, but no emissions or smog tests. And why would I be failed for no rear cats? I have them currently and I am buying new ones, as stated in my previous post. No real need for the negativity.

 

[gavin]

We do have inspections, but no emissions or smog tests. And why would I be failed for no rear cats? I have them currently and I am buying new ones, as stated in my previous post. No real need for the negativity.

federal law says you cannot remove any catalytic converter that comes equipped OEM, iirc.

state law (generally) says you cannot modify any emission equipment on a vehicle. Catalytic converters being part of the emissions system.

As for passing an emissions test really depends.
Some states/cities/counties/what have you only do ECM tests. Some areas also do visual inspections.
You may or may not pass a visual inspection depending on the tech doing the emissions testing and their knowledge of the OEM equipment on the vehicle.

 

[Joe Dirt]

Dealership here in GR replaced the 4 junk cats on my old '97 V8 with 2 cats. We do not have emissions testing here in MI.

Per an earlier argument eruption about it, I don't know if it was legal or not- it was the semantics of putting on 4 if 4 came off, or if 2 replacing 4 was ok- I have no idea. All I know is the dealer did it, I didn't care, it was fixed and I never had issues.

 

[CDW6212R]

Dealership here in GR replaced the 4 junk cats on my old '97 V8 with 2 cats. We do not have emissions testing here in MI.

Per an earlier argument eruption about it, I don't know if it was legal or not- it was the semantics of putting on 4 if 4 came off, or if 2 replacing 4 was ok- I have no idea. All I know is the dealer did it, I didn't care, it was fixed and I never had issues.

Nice, big cats(and 2.5").

 

[ZebraT]

Here in Colorado, they're supposed to do a visual inspection before testing, but I haven't seen them do it in the last few years. I'm not sure if it's no longer a priority or if the people working at the state-licensed emissions facilities don't give a *#$@ anymore.

Anyways, you can buy a couple cats cheap...I found this on eBay for $100

http://www.ebay.com/itm/Walker-93237-Universal-Converter-/380525977247

Seems like $200 or so ought to do it. If you sell the old ones for scrap, that's like $100.

 

[CDW6212R]

Here in Colorado, they're supposed to do a visual inspection before testing, but I haven't seen them do it in the last few years. I'm not sure if it's no longer a priority or if the people working at the state-licensed emissions facilities don't give a *#$@ anymore.

Anyways, you can buy a couple cats cheap...I found this on eBay for $100

http://www.ebay.com/itm/Walker-93237-Universal-Converter-/380525977247

Seems like $200 or so ought to do it. If you sell the old ones for scrap, that's like $100.

That is higher than the $50 I paid many years ago for a similar Catco universal unit, exactly like the Mac cat pipe units I had.

 

[rizzjc]

So, here is a question. Had anyone ever replaced a cat due to bad fuel economy, and had it make a difference? I replaced my O2 sensor, which seems to have fixed the code it was throwing now and then, but I'm wondering if after 220k miles, my cats could be dump of junk, and not flowing well, despite the fact that the sensors say they are working ok. Thoughts?

 

[CDW6212R]

Yes when they do begin to plug up, it will hurt performance and fuel economy. It's just very hard to catch between working fine, and being plugged.

 

[rizzjc]

I'd just hate to spend the money, and my fuel economy is still in the crapper.