So my catalytic converter has imploded (asking for advice)

JamesAndTheSahara

JamesAndTheSahara

TJ Addict
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May 22, 2017
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Location
Auburn, AL, United States
I recently incurred a problem on a cold start where I will loose all acceleration and will regain it after the engine bogs for 10 seconds & revs right back up. Super annoying driving around town because I can't hit the speed limit and hold everyone up (Also pretty unsafe at this point). I took it into my mechanic and really didn't expect it to be my catalytic converter (However it has been rattling like crap & the original). My peer had some work done at a local muffler shop in Auburn so I dropped her off there today to have them to a good look at her exhaust & more than likely replace the Catalytic converter. Here are my questions:

1998 Jeep Wrangler Sahara
4.0L Inline 6, 5 Manual Transmission, Stock exhaust components
  • I know for certain I need to replace the cat, should I have anything else done while they have it?
  • I understand that no muffler will give me any type of performance boost, is there a muffler any of you are running that you like (Please indicate if you have any type of drone or Loud pipes as it won't help as its not what I'm personally interested in on my TJ)?
  • Does those mini catalytic converters in the front need to be replaced as well? Or just the larger one (#1)?
I attached a picture below for reference as I believe this is exactly how my TJ is setup (I don't know for sure I didn't really poke around much). Thank you all so much for your help in advance!

I6 exhaust.jpg
 
JamesAndTheSahara said:
I recently incurred a problem on a cold start where I will loose all acceleration and will regain it after the engine bogs for 10 seconds & revs right back up. Super annoying driving around town because I can't hit the speed limit and hold everyone up (Also pretty unsafe at this point). I took it into my mechanic and really didn't expect it to be my catalytic converter (However it has been rattling like crap & the original). My peer had some work done at a local muffler shop in Auburn so I dropped her off there today to have them to a good look at her exhaust & more than likely replace the Catalytic converter. Here are my questions:

1998 Jeep Wrangler Sahara
4.0L Inline 6, 5 Manual Transmission, Stock exhaust components
  • I know for certain I need to replace the cat, should I have anything else done while they have it?
  • I understand that no muffler will give me any type of performance boost, is there a muffler any of you are running that you like (Please indicate if you have any type of drone or Loud pipes as it won't help as its not what I'm personally interested in on my TJ)?
  • Does those mini catalytic converters in the front need to be replaced as well? Or just the larger one (#1)?
I attached a picture below for reference as I believe this is exactly how my TJ is setup (I don't know for sure I didn't really poke around much). Thank you all so much for your help in advance!

View attachment 20503
Click to expand...

That photo you attached is incorrect. That's for the 2000+ model 4.0s when they started adding the pre-cats. Yours doesn't have pre-cats on it (be thankful), so you only have ONE catalytic convertor that needs to be replaced.

A replacement cat isn't that much. You can buy a Walker direct fit (bolts right on) replacement for $154:
https://www.amazon.com/dp/B000C946HW/?tag=wranglerorg-20

That is the exact part number you need for your year and make. In addition to that, I suggest replacing the O2 sensors at the same time if your wallet permits. They aren't that much money, but it will be great piece of mind.

There's a thread about it here:
The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

In summary though, if you replace the O2 sensors, you only need the following parts:
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

I use a Flowmaster muffler on mine and like it a lot. It groans louder than stock at wide open throttle, but it doesn't drone whatsoever, which is nice.

Sometime I wish my TJ was a pre-2000 model. It's nice not having all that extra emission bullshit on it!
 
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Chris said:
That photo you attached is incorrect. That's for the 2000+ model 4.0s when they started adding the pre-cats. Yours doesn't have pre-cats on it (be thankful), so you only have ONE catalytic convertor that needs to be replaced.

A replacement cat isn't that much. You can buy a Walker direct fit (bolts right on) replacement for $154:
https://www.amazon.com/dp/B000C946HW/?tag=wranglerorg-20

That is the exact part number you need for your year and make. In addition to that, I suggest replacing the O2 sensors at the same time if your wallet permits. They aren't that much money, but it will be great piece of mind.

There's a thread about it here:
The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

In summary though, if you replace the O2 sensors, you only need the following parts:
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

I use a Flowmaster muffler on mine and like it a lot. It groans louder than stock at wide open throttle, but it doesn't drone whatsoever, which is nice.

Sometime I wish my TJ was a pre-2000 model. It's nice not having all that extra emission bullshit on it!
Click to expand...
You are the bomb Chris. I'll make sure I take this knowledge with me tomorrow when I go to tell them what I want done. They keep Magnaflows & Flowmasters in stock so more than likely going to go with one of those (Preferably one that isn't packed).
 
Not to hi jack the thread but mine is rattling sometimes on idle right under my seat. It's '05 so maybe both as well,..

The above image would be correct?


Sent from my iPhone using Tapatalk
 
JamesAndTheSahara said:
You are the bomb Chris. I'll make sure I take this knowledge with me tomorrow when I go to tell them what I want done. They keep Magnaflows & Flowmasters in stock so more than likely going to go with one of those (Preferably one that isn't packed).
Click to expand...

Both of those muffler options are good ones, you won't be disappointed!

Shane Mckinley said:
Not to hi jack the thread but mine is rattling sometimes on idle right under my seat. It's '05 so maybe both as well,..

The above image would be correct?
Click to expand...

Yes, the above image would indeed be correct for your 2005.
 
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Just an update I had the Cat replaced with the best one the shop could buy & had a magnaflow welded on. Still didn't completely fix this ridiculous issue I am troubleshooting but the exhaust no longer rattles like hell.
 
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JamesAndTheSahara said:
Just an update I had the Cat replaced with the best one the shop could buy & had a magnaflow welded on. Still didn't completely fix this ridiculous issue I am troubleshooting but the exhaust no longer rattles like hell.
Click to expand...

Did you do the O2 sensors by chance?
 
Chris said:
Did you do the O2 sensors by chance?
Click to expand...
Yeah I had them replaced because they were seized & he needed to remove them to weld the new equipment on. The TJ has been doing this weird issue where on a cold start after 15 seconds of driving the engine will lug down to 1500 rpm even with the pedal to the floor in any gear. Even with the clutch depressed and trying to rev it up it still won't pass 1500 rpm. After 30 seconds of driving the jeep goes back to normal.

Here's what I have replaced troubleshooting this:
  • New Catalytic Converter
  • New O2 Sensors
Spark plugs should be fine I had those replaced a little while ago, so that should be unrelated. The Issue is not as significant with the new Cat installed, but it is definitely still there.
 
JamesAndTheSahara said:
Yeah I had them replaced because they were seized & he needed to remove them to weld the new equipment on. The TJ has been doing this weird issue where on a cold start after 15 seconds of driving the engine will lug down to 1500 rpm even with the pedal to the floor in any gear. Even with the clutch depressed and trying to rev it up it still won't pass 1500 rpm. After 30 seconds of driving the jeep goes back to normal.

Here's what I have replaced troubleshooting this:
  • New Catalytic Converter
  • New O2 Sensors
Spark plugs should be fine I had those replaced a little while ago, so that should be unrelated. The Issue is not as significant with the new Cat installed, but it is definitely still there.
Click to expand...
what's your fuel pressure doing during this?
 
crackedcornish said:
what's your fuel pressure doing during this?
Click to expand...
So I'm not the best with fuel injected cars so I don't really know how I would test the fuel pressure or know how it is during it. Temperature/Gas/Oil Pressure appears fine. Do I need a proper OB2 scanner that can read the port while I drive to test it or a compression kit for the fuel pressure. I'm guessing its the later, I'll see if I can find a peer with a kit & test it. I can only assume its the factory fuel pump & 160k on it currently.
 
What brand of O2 sensors did you use?

Have you tried resetting the CEL and it still comes back?
 
Hmmm, so no check engine light (I missed that part), but it still bogs and runs like crap? That's shocking, usually that will set off a check engine light. If you took it to your mechanic though, shouldn't they have been able to figure it out?
 
When I took it to a Firestone, they stated it was the Catalytic converter gone bad, 100% sure of it. Again there is no CEL and the bulb works trust me lol. I am not using a K&N Air filter, I am running an AC Delco that is clean of all debris.
 
I would look at this as an opportunity to buy a new tool(s), such as the fuel pressure gauge mentioned above. But then I really like tools and will buy them even if I only use them once. And that may not be the best thing for you to do. I know my wife is not a big fan of that mindset.
It sounds like the problem is fairly consistant, so a good tech should be able to sort it out. Steer clear of the franchise shops and find an independent shop with good reviews. Ask around, see who your friends trust their car too. Some chain dealerships are known for taking advantage of customers, for example they replace the entire harness when you only need one connector replaced. Without a code, without a good scanner, you could just end up replacing parts till you get lucky and find the problem. So I recommend you check around and find a good honest tech.

Best of Luck,

B
 
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