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Old 09-19-2017, 12:09 PM
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3.8l Catalytic Converters replacement

Seems like a pretty straight forward procedure to DIY. Anyone have any pointers, tips or 'gotcha's I should be aware of?


Backstory:
My 2007 Wrangler now has 110k miles.

Two years ago I got in a rear end accident...hit the vehicle in front of me at about 15mph which was hard enough to bend up my front bumper and to cause the exhaust system to move enough that the upper cat (driver's side) hit a protruding bolt and got a puncture. I had patched that hole with hi temp metallic epoxy and a stainless sleeve but regularly get CEL codes for the cat efficiency (P0430); I am guessing the patch did not seal well and this would probably accelerate the degradation of the cat(s) on that side.

I lived with that for a while, but after a 1300 mile trip to Atlanta and back (Irma Bug-out) the engine is starting to have a miss or skip when in overdrive at a steady, slower speed. Almost like it wants to momentarily stall. Turning OD off or increasing RPM makes it go away. Just recently got a 'cylinder misfire' CEL code.


I am pretty confident that the cats are shot...at the very least, due to the age and puncture. I ordered a direct fit replacement from a seller in Canada, just over $300 including shipping.
http://www.ebay.com/itm/202048321293

I plan to reuse the new O2 sensors I have on the Jeep now. (I have too many other toys and projects to be able to drop a grand on magnaflo or other top end plumbing)


Notes:
-All O2 sensors were replaced 9 months ago
-All ignition wires, coil pack and plugs changed out 6 months ago
-no noticeable exhaust leaks around heads
-Cats and exhaust piping on driver's side have a copperish dark tinge (running hot?)

Image of cat with sleeve patch; note the dark and rust/copper colors. Can also see the stainless sleeve clamped on:


-Mileage has been low for a year or two...avg 12-13 in town, 14-15 highway.
-been noticing that the Jeep is more sluggish, especially on slight inclines (overpasses on highways)...it will downshift from OD even on modest or minor inclines at highway speed.
-I haven't had the emissions tested...Although that would be definitive....not required in FL.

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Old 09-19-2017, 02:59 PM   #2
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On the 3.8L, there is a single set of piping that goes from exhaust header to catalyst to pipe and then to the exhaust connector.

So assuming you got a proper replacement, you'll be getting this U/Y shaped thing.

Replacing on the exhaust header side is simple. You -will- need new bolts there. It only takes a few heat cycles for bolts/nuts to pretty much lock on themselves.

On the other side of the Y where it connects to the rest of the exhaust, expect it has fused itself. You'll likely need to cut the Y pipe prior to the joint and then cut or otherwise separate the connector. Along with this you will need to replace the exhaust clamp at that location as well. (It likely will not be reusable after 100k miles.)
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Old 09-19-2017, 04:12 PM
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Quote:
Originally Posted by mhatle View Post
On the 3.8L, there is a single set of piping that goes from exhaust header to catalyst to pipe and then to the exhaust connector.

So assuming you got a proper replacement, you'll be getting this U/Y shaped thing.

Replacing on the exhaust header side is simple. You -will- need new bolts there. It only takes a few heat cycles for bolts/nuts to pretty much lock on themselves.

On the other side of the Y where it connects to the rest of the exhaust, expect it has fused itself. You'll likely need to cut the Y pipe prior to the joint and then cut or otherwise separate the connector. Along with this you will need to replace the exhaust clamp at that location as well. (It likely will not be reusable after 100k miles.)
Thanks for the tips!
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Old 09-21-2017, 02:01 AM   #4
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Let us know how the quality and fitment of that cat for that price its a great deal I would buy one just to keep around for when I need it.
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Old 09-21-2017, 07:07 AM   #5
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In case you are worried it's not the cat don't be. The symptoms you are describing is exactly what I went through on my truck when it had a bad cat.
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Old 09-21-2017, 10:27 AM
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@oak4627 : I will take pics of the product and install and post them here. should be here in a week. Also ordered new flange bolts and retainer nuts (exhaust manifold to cat bolts, per Mhatle's recommendation above).

@Hansoon : Thanks, I appreciate the confirmation!
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Old 09-25-2017, 09:01 PM
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I am spending too much time thinking about this and it will take awhile before the cats come from Canada (en route now, est another 4-6 days)....so ordered a new cat-back exhaust. I figured, since I will probably have to beat up the mid pipe to get the cats off, may just as well just keep on replacing downstream.

https://www.quadratec.com/products/17613_3000_07.htm
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Old 09-30-2017, 08:45 PM
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Cats came Friday; 10 days from order to delivery. Spent around six hours under the Jeep today installing the cats and Pypes cat back exhaust.






I pulled the fenders off (definitely made this a lot easier) and also dropped the skid plates and transmission crossmember to install the cats. Tried to put it in with the crossmember in place, but just couldn't seem to be able to work it in.






Getting the old exhaust out was facilitated by cutting it up to manageable pieces (since I was replacing anyway).



The old cats spewed a bunch of crud out on the ground when I got them out and tipped them up although they didn't look too bad.







This is what the new ones look like:



The Pypes exhaust looks nice and loses a lot of weight in the back since it replaces the stock muffler:




Sounds nice...definitely louder (as expected) but has a nice growl

http://www.thefishtank.cc/fishbox/pi...st/running.mp4


My P0430 CEL is gone...but now getting a P0300 (random misfire). When I test drove it, it has some serious hesitations, almost felt like it was gonna stall, and stomping on the gas made the engine sputter. Going to try replacing the Crank Position Sensor...google searching this CEL seems to point to this more often than not. (I have already replaced the plugs, ignition wires, and coil pack just recently). Will also do the "spray carb cleaner" on the intake manifold while running to see if there may be a vac. leak around there...but it was running ok and did not have this issue before re plumbing the exhaust.
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Old 10-01-2017, 04:16 PM
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Ended up pulling the plugs. They looked ok, a little dry looking and gaps off to about .55 on a few. These were only a year old, but did have some hard miles on them. Put in new plugs and the P0300 went away and it's running great.

Also removed the throttle body and gave it a good cleaning. front was ok, the back of the butterfly was pretty coated.

Overall weekend project: New cats, new exhaust, new crank position sensor, new plugs all for around $650.
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Old 10-01-2017, 08:31 PM   #10
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Keeping an eye on this.
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Old 10-15-2017, 04:50 PM
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Quote:
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Ended up pulling the plugs. They looked ok, a little dry looking and gaps off to about .55 on a few. These were only a year old, but did have some hard miles on them. Put in new plugs and the P0300 went away and it's running great.

Also removed the throttle body and gave it a good cleaning. front was ok, the back of the butterfly was pretty coated.

Overall weekend project: New cats, new exhaust, new crank position sensor, new plugs all for around $650.
Even after changing the plugs, I started getting the misfires again. Replaced the coil pack and cleaned the leads to the battery* and this resolved.

*The positive battery wires have ring terminals which go on a wing nut lug that is clamped to the anode. In between the terminals there was quite a bit of oxidative corrosion. I used a file to clean these down to shiny copper.
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Old 10-15-2017, 05:10 PM
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A couple of post install notes:

1. Great write up on JK-Forum here: https://www.jk-forum.com/how-tos/a/j...nverter-407293

2. Soak the manifold bolts with PB Blaster, I had no problem removing them...in fact it was surprisingly easy.

3. the above write up describes removing the heat shields from the exhaust manifolds; It was not necessary for me..I left them on and had no problems.

4. I have never before removed the transmission cross member...didn't realize it was supporting the transmission (or is it the transfer case?). Luckily I had a floor jack under it when I pulled the last bolt out...could've been a bad day
I did not remove the fuel tank skid plate..was able to slide the crossmember out from under it after unbolting the xmember and tcase bracket bolts.

5. removing the fenders really helps give access to the bolts and O2 sensors. If you haven't removed fenders before, be prepared with replacement body panel clips...about half of mine broke when pulling the fender off.

6. I bought one of those plier-like tools for removing exhaust hangers. It helps, but half the hangers are situated such that you can't get the tool on to them (too close to the frame)...so in those cases I resorted to channel locks.
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Old 07-09-2018, 05:11 PM   #13
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How has this third-party, non-MOPAR catalytic converter held up since last year? Did replacing it and using catback exhaust improve your MPG at all? Thanks.
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Old 09-19-2018, 01:28 PM
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How has this third-party, non-MOPAR catalytic converter held up since last year? Did replacing it and using catback exhaust improve your MPG at all? Thanks.
Sorry, been a while since I looked at this thread or been on the forum. MPG went up about 2 mpg. Nothing to brag about, but moved the right direction

No Cat CEL since.
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Old 11-24-2018, 10:07 PM   #15
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Originally Posted by notdeankane View Post
Seems like a pretty straight forward procedure to DIY. Anyone have any pointers, tips or 'gotcha's I should be aware of?


Backstory:
My 2007 Wrangler now has 110k miles.

Two years ago I got in a rear end accident...hit the vehicle in front of me at about 15mph which was hard enough to bend up my front bumper and to cause the exhaust system to move enough that the upper cat (driver's side) hit a protruding bolt and got a puncture. I had patched that hole with hi temp metallic epoxy and a stainless sleeve but regularly get CEL codes for the cat efficiency (P0430); I am guessing the patch did not seal well and this would probably accelerate the degradation of the cat(s) on that side.

I lived with that for a while, but after a 1300 mile trip to Atlanta and back (Irma Bug-out) the engine is starting to have a miss or skip when in overdrive at a steady, slower speed. Almost like it wants to momentarily stall. Turning OD off or increasing RPM makes it go away. Just recently got a 'cylinder misfire' CEL code.


I am pretty confident that the cats are shot...at the very least, due to the age and puncture. I ordered a direct fit replacement from a seller in Canada, just over $300 including shipping.
http://www.ebay.com/itm/202048321293

I plan to reuse the new O2 sensors I have on the Jeep now. (I have too many other toys and projects to be able to drop a grand on magnaflo or other top end plumbing)


Notes:
-All O2 sensors were replaced 9 months ago
-All ignition wires, coil pack and plugs changed out 6 months ago
-no noticeable exhaust leaks around heads
-Cats and exhaust piping on driver's side have a copperish dark tinge (running hot?)

Image of cat with sleeve patch; note the dark and rust/copper colors. Can also see the stainless sleeve clamped on:


-Mileage has been low for a year or two...avg 12-13 in town, 14-15 highway.
-been noticing that the Jeep is more sluggish, especially on slight inclines (overpasses on highways)...it will downshift from OD even on modest or minor inclines at highway speed.
-I haven't had the emissions tested...Although that would be definitive....not required in FL.
What do you think about the brand catalyzer you used ?
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Old 02-11-2019, 10:10 AM
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What do you think about the brand catalyzer you used ?
no problems to date. definitely a good buy.
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Old 02-11-2019, 10:41 AM   #17
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no problems to date. definitely a good buy.
Did you transfer the crossver pipe heat shield or just leave it off? That heat shield causes a lot of noises, would be neat if it can be eliminated.
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Old 05-20-2019, 11:00 AM
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Did you transfer the crossver pipe heat shield or just leave it off? That heat shield causes a lot of noises, would be neat if it can be eliminated.
sorry, haven't been on this forum for a while. I did not reuse the heat shield, just installed the crossover pipe as it came out of the box.

I did notice the driver's side of the crossover was rubbing against the frame. Since it is a 2-piece pipe, make sure to spread the sections apart as much as possible before clamping them together to prevent this.

Have since traded in the 07 for a '15 so no more problems...
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Old 08-07-2019, 01:39 PM   #19
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how long after did you make the trade? just outta curiosity
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Old 08-07-2019, 04:56 PM
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how long after did you make the trade? just outta curiosity
Just over a year and 9 months or so
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Old 09-03-2019, 03:10 PM   #21
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Just over a year and 9 months or so
thank you for getting back!
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