Catalytic Converter Help

[Rizzu]

I've been having an issue the last 2-3 weeks with acceleration/idle sputtering after about 15-20 minutes of my KJ warming up. I replaced all my spark plugs and coils about 4 months ago, so everything I can tell now narrows it down to the Catalytic Converter being clogged or the Fuel Filter being dirty (i'm trying to pretend the latter isn't the problem considering it's location).

The plan was to drop the cat, hollow it out, toss it back up. Emissions testing isn't enforced where I live so it was the cheaper option than replacing it with a Magnaflow system.

Now here's what i'm confused about... I'm not 100% sure where it is, or what it looks like. After extensive googling/youtubing, i can't find anything on the KJ location for a cat converter, plenty for civics and older vehicles though. The closest thing to resemblance i could find was this under the passenger side (attached). I removed the o2 sensors, dropped it down, looked inside and it was already completely hollow leaving me to believe that:
a) I have the wrong part and just wasted a bunch of time removing and reinstalling it.
b) Someone beat me to it.

I realized afterwards that there is another one of these (attached) on the driver's side. Before removing and checking that, i wanted to make sure i wasn't wasting my time looking in the wrong area. Help!

TLDR: Do KJ's have two catalytic converters? Is the part in my attachment the catalytic converter? If i'm totally wrong, does anyone have a photo of where i should be looking?

Thanks!

 

[CzarKJ]

I don't have the answer to your question but have you checked your tps sensor and replaced O2 sensors? Those could also be an issue before the cat.

 

[Rizzu]

I don't have the answer to your question but have you checked your tps sensor and replaced O2 sensors? Those could also be an issue before the cat.

That's an excellent suggestion! I'll swap out the TPS first and see if that rectifies the problem, then move to the o2's after. Thank you

*edit- The two torx bolts were so tightly seized on, they twisted the head a solid screwdriver and a separate torx bit to the point where they can no longer function. Soaked them in penetrating fluid and i'll try again in an hour. Stupid bolts.

 

[TwoBobsKJ]

Your pic shows one of the THREE catalytic converters on the KJ. There is one attached to each exhaust manifold on both banks of the 3.7 gasser engine and a third downstream of the Y pipe and before the muffler.

Only the two cats attached to the exhaust manifolds have O2 sensors; there are two sensors on each cat. One is upstream of the actual converter and one is downstream.

If your cats are indeed hollowed out then you're likely to get all kinds of codes and a very poorly running engine. The computer is looking for specific readings from the O2 sensors and with empty cats they're not going to get anything close to what they're expecting. There are aftermarket cats available from manufacturers like Walker that are a direct fit and are significantly cheaper than Mopar replacements.

Bob

 

[Rizzu]

I replaced the TPS after fighting with the bolts which were covered in Lock Tight from whatever sadistic person installed it before. The idle sounds cleaner which is promising but i won't know for sure until it's on the road for a few minutes when i'm done work for the day. Fingers crossed!

And thank you Bob for the reply, there's THREE?? If the problem's still there tonight, i'll rip the other two off and examine them. The one i pulled off was dented up pretty badly so i think someone literally just pounded on the outside with a hammer to break up the insides and hollow out that way. The other one i saw looked a lot less abused so it's possible that's the one that's all clogged up.

Thank you both!

 

[John3seventeen]

If it was clogged and not functioning your check engine light should be on.

 

[Rizzu]

Guiltily, it has been for some time now. When i first had the error code checked, it came back as the top and bottom sensor going off. I was told that the main issue i'd have is a slight decrease in gas mileage and considering Calgary's harsh winter and not having a viable location to work on it, i shrugged it off since i wasn't experiencing any noticable issues.

Only recently have i been experiencing troubles which was the kick in the ass i needed to get to work on it.

 

[Renedave]

Each downpipe from the engine should have two O2 sensors, the catalytic converters are between them. If you think the cats are plugged then remove the upstream O2 sensors and see if the problem goes away. Be warned that this will cause the engine to run in open loop configuration for fuel metering, and it's generally a bad idea to do this for longer than it takes to diagnose the problem.

I believe what you've pictured is the resonator.

The downstream O2 sensors have little to no impact on engine performance, their purpose is to measure catalyst efficiency during the rich/lean test cycle and make sure the emissions equipment is operating properly.

Walker cats are junk. Go ahead and use them if you're getting rid of the Jeep in less than a year, otherwise you'll be replacing them again. I have personal experience with this after crushing one of my cats off-roading, and it took less than 15k miles for both Walkers to plug up and leave the Jeep barely able to limp off the highway and into a parking lot. After that I sucked it and bought an OEM Y-pipe. Years later it's still going strong (knock on wood).

See if you can get a local auto parts store to give you a readout of the codes, that'll help in troubleshooting.

 

[TwoBobsKJ]

I believe what you've pictured is the resonator...

Nope, that's one of the cats - pretty sure the passenger/right side. You can see the fitting for the upstream O2 sensor on the bottom side of the pic (the converter is upside down in the pic.)

FWIW, I've had a pair of Walker direct fit cats on mine for almost three years and 45,000 miles and they've been fine. I had to change engines but the Walker cats are still there :cheers:

Bob

 

[slipinkramer]

Beg, borrow or steal an OBDII scan tool. Plug it in under the dash, warm up the engine and look at the O2 sensor wave forms and the short term and long term fuel trims.

This may very well show you what's going on. Please don't destroy your catalytic converters...

 

[2nd]

I know this is an old thread but I was trying to figure out how to remove the dr side cat pipe, from the manifold end, looks like a V band type clamp? from underneath. any help plz? oh its a 2002 Liberty

 

[ltd02]

I know this is an old thread but I was trying to figure out how to remove the dr side cat pipe, from the manifold end, looks like a V band type clamp? from underneath. any help plz? oh its a 2002 Liberty

I had this same question when I removed my heads last spring to change the gaskets. I was instructed by TJKJ to use an 10mm ratcheting stubby wrench and it worked like a charm. Yes from underneath and it is very tight in there!

 

[libertybob]

Clogged Cats

My experience is that a clogged cat is a secondary failure from another problem with the engine. Unburned fuel in exhaust gases can cause overheating and melted cats. Look for the root cause that caused a clogged cat. This doesn't just happen from normal use.

 

[2nd]

thanks Ltd, and its not a clogged cat, libertybob it is leaking exhaust gas from the heat shield weld, I was going to remove it and weld it up if there is enough material left. it has 168k

 

[TwoBobsKJ]

I had this same question when I removed my heads last spring to change the gaskets. I was instructed by TJKJ to use an 10mm ratcheting stubby wrench and it worked like a charm. Yes from underneath and it is very tight in there!

Yep, that's how to get it out of there. Ratcheting box end wrenches are a beautiful thing :waytogo:

As for the V-clamp... If yours is shot (and you're not supposed to reuse them) only get a Mopar clamp. I tried others and they don't close tightly enough to hold the cat flange to the manifold flange and you'll get exhaust leaks. Unfortunately I found that out the hard way and I was plenty *#($#+#!@ at myself for having to do that job twice :favorites68:

Bob

 

[M38 Bob]

The Cat you pictured was hollow???? That means either some numb nuts Mr.Goodpliers has hollowed it, OR the guts broke up and are lodged in a pipe downstream (probably in the neck of the previously mentioned 3rd, downstream, converter). You can usually hear broken media by tapping on the pipe in various places with your palm, or a rubber hammer. If chunks of media are downstream, it'll run like schit periodically depending on how the chunks get turned (more or less restrictive)

I install universal cats quite often(operate a muffler shop), usually less than $175 each, and seldom ever have a comeback. Those are almost always because the vehicle owner didn't have the root cause of original converter failure fixed.

Bob

 

[Hapster]

I just got a 0420 and 0430 code on my Liberty. Is it possible for both of the cats to go bad at the same time? Could it be something else causing those codes?

 

[CzarKJ]

Sounds more like a air sensor or something. Both going bad instantly is highly doubtful and both o2 sensors going bad as well is crazy.

 

[Hapster]

I just changed one of the upstream sensors a few days before the codes came up. I failed my emissions test because of the codes. The jeep feels a little sluggish on the highway.

 

[ltd02]

I just changed one of the upstream sensors a few days before the codes came up. I failed my emissions test because of the codes. The jeep feels a little sluggish on the highway.

What brand sensor? These things only like the NGK OEM type.