one_speed_heuer

Where would the other 2 cats be on the exhaust system? Out of all the time Ive spent on any of my vehicles ive only seen 1 cat converter per tail pipe. Only time Ive seen 2 cats was on my friend 88 Malibu and he has basically everything customized. I can see there being a few sensors for the exhaust and air but I cant see there being more than one cat.

PocketsEmpty

Newer vehicles have more, smaller cats. I don't really know why, but it's stupid. my 99 Ranger had 3 cats as well.

one_speed_heuer

I feel stupid now, just did some reading and it could be a California emission system. And I knew there was some reason I didnt like most new vehicles. In my mind my 99 XJ has far too much technology, get rid of my cruise control and power windows.

But I have never noticed any extra things that could look like an extra converter.

Radi

Can't modify the OEM emissions equipment, even if it's Cali emissions and the component isn't required in your (not-Cali) state.

You don't need it, but if it's there you can't remove it.

CrawdadSlim

I've heard the two precats are glorified screens.

Firestorm500

Some vehicles have pre-cats before the main cat in order to satisfy ever-stringent pollution control regulations.

Since our XJ engines were originally designed in the early 1980s, from their predecessors from the 70s and earlier, they did pretty well in the emissions department.

salad

In 2000+ Chrysler started adding a CARB/50-state emissions package to all 4.0Ls. I think by 2001 or 2002 it was mandatory. In this system there are monitored two mini-cats and a single large cat.

The mini-cats, an accompanying O2 sensors (four total) are used to analyze the basic efficiency of the engine and adjust the air:fuel ratio, and since 2000 the PCM will adjust AFR based on catalyst performance. Previous models used two O2 sensors that monitored the big cat under the passenger seat. This was subject to lag and cooling (bad for performance) and many leaks (bad for performance and emissions). As they are placed right in the exhaust manifold they provide MUCH more accurate and responsive feedback to the PCM of how the engine is burning fuel and leaks are much less of an issue. The large catalytic converter is no longer monitored but still the main method of exhaust gas treatment. This was okay in the EPA's opinion because a failed upstream will throw a code, and downstream is less likely to clog, but is also noticeable if it falls off. Not to mention very illegal and any shops that cut out emissions control components can be nailed with fines.

I agree with previous posters. Firestorm500's idea especially. No shop should EVER be offering to break the law for you. In a jurisdiction with gas analyzer or visual inspection your Jeep would fail immediately.

However if you want to let them get away with ripping people off and polluting the environment the high-flow cats at performance-curve.com are a pretty good option. At least name the *******s.

^^^ this and fuel economy are what killed the 4.0L.

CCKen

I don't know for sure, but I theorize that the 2000 - California, and 2001 - 50 States, emissions requirements are stiff and that inorder to catch excess exhaust emissions prior to the exhaust gases getting hot enough to make the upstream catalytic converters effective enough, the downstream (unmonitored) catalytic converter helps remove the excess emissions.

Note that the Oxygen Sensors have electric heaters to bring them up to operating temp until the exhaust gases have reached a high enough temp that the heaters are no longer required,

My opinon ( see my signature ).

PocketsEmpty

Right, I think it really depends on location. Some states don't require inspection at all, and some mechanics won't dig deep into the OEM specifics to check for things during inspection. The OP's profile states that he is in Wisconsin, which a quick Google search seems to reveal stringent emissions inspection and laws. In this case I'd agree with everyone else--go back to that shop and tell them that what they did could cost them in fines and more unless they put a cat back in there. I suppose if you didn't want to make a scene, and trust your mechanic and he's the only guy you ever go to, I'm sure you'd be fine...but you'd have to keep that in mind if you ever went to someone else.

one_speed_heuer

In Wisconsin it all depends on what county you're in. I'm in outagamie and we don't have to test out vehicles. It's only really in the south eastern part that they test. I know from experience that a few people don't have cat converters anymore. But the vehicles sound terrible and smell bad too. I almost bought a truck with out one til I saw floor rust.

But I'd report the shop to law enforcement. I'm pretty sure you're not the first person this has happened to. And you won't be the last. If the cat was bad I think they would have just left it on your jeep until you got a new one.

Xpress

To further illustrate the point, MAKE them put a brand new CAT back in. If they cut it out and intentionally broke a Federally mandated law in all 50 states then they are at serious risk for fines out the *** and possibly having their shop closed down.

All it takes is for one person like you to rat them out and they're done for. As much as I hate seeing shops go down, especially in this economy, they have a certain set of laws they are required to follow and they have to be held accountable. It's what sets the outstanding and honest shops apart from the shady and sketchy shops. I'm sure they'd much rather put in a brand new CAT for you than face the Feds.

As far as SMOG testing goes, it depends entirely upon your location and the population there. California may require SMOG testing for every California vehicle, but not all vehicles have to go back to get SMOG tested every 2 years- it all depends on where you live. A buddy of mine lives in the mountains where very few people reside and he was only required to SMOG his truck one time over a decade ago, they haven't bothered him since. From what I've heard, his brand new car doesn't ever need to be sniffed on the dyno either.

Arizona on the other hand, you will find that they do make people SMOG their vehicles in more densely populated areas, but not everywhere.

DFlintstone

Edit; Whoops. They are valuable scrap, (platinum?), that shop did you no favor.

one_speed_heuer

It seems like youre setting up for blackmailing the shop. Id almost be scared to go back to that shop and have them install a new converter(especially on their dime), Id be afraid they would screw up something else on my vehicle, I went in for an alignment at a shop thats known to try to screw people over, and somehow a O2 sensor that was only about a year old decided it wanted to die. Needless to say Im never going back to that shop. They do good alignments though, Ill give them that.

DFlintstone

Just politely tell him you found that the cat he removed is required, and ask him to please put it back? If he's legit and honestly didn't know, better he does know, and if he did it on the sly, fine, he will likely be all to happy to set you up with no hassle.

Cherokee19

For 100 bucks they put a new one in. Done deal.