post #1 of Old 11-11-2013, 04:00 PM Thread Starter
davidmatlack
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1996 ZJ 
 
Join Date: Aug 2012
Location: rocky mount
Posts: 183
Catylic Coverter

How do you know if one has gone bad? No code has popped up and no rattle in it like my last one that I replaced 100k ago. Muffler is original but no holes/breaks. 264k on vehicle. Had since day one.

Best- David

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post #2 of Old 11-11-2013, 04:10 PM
WJ4x4LIFE
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There are two ways a converter can fail:

1.) It can become clogged.
2.) It can become poisoned.

There really is no "inspection port" for someone to view, unless opened by torch. Some may say there usually is a noticeable drop in gas mileage associated with a clogged catalytic converter. A totally clogged converter may cause a lot of known issues with one being, the smell of rotten eggs (theory). I can't say I have smelled this before, but maybe I can smell ****! who knows? A consistently high idle, or erratic idle issue, no hard acceleration issue, and many others. (Symptoms) Physically, you can hear them fall apart from the inside (rattle), or hear them coming apart from the welds over time is a known issue.
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post #3 of Old 11-11-2013, 04:15 PM
coralman
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Search you tube " how to detect bad cat converter". There is a video where a guy uses an infrared thermometer to trobleshoot cats.

Info on projects and repairs categorized by system
http://www.jeepforum.com/forum/f13/c...-faqs-2863665/

Originally Posted by HighLonesome
lol...if life is as a simple as a 5.9 making you happy, I'd say go ahead and buy it on impulse. ZJs are the way of Zen. Wax on, wax off
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post #4 of Old 11-12-2013, 04:36 PM Thread Starter
davidmatlack
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Thanks for the reply. Gas mileage has gotten bad 12mpg city and 18 hwy. Hwy fine. Sorry I don't use or ever will, U-Tube.
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post #5 of Old 11-12-2013, 05:24 PM
JasonStebbins
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Quote:
Originally Posted by davidmatlack View Post
Thanks for the reply. Gas mileage has gotten bad 12mpg city and 18 hwy. Hwy fine. Sorry I don't use or ever will, U-Tube.
It may become clogged which can cause overheating and power issues and the honeycomb inside can collapse.

There's a 100 things that could affect your gas mileage, why do you think the converter is bad?

Poop
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post #6 of Old 11-12-2013, 06:21 PM
ZeeJay1997
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Quote:
Originally Posted by rlcii77 View Post
my Orvis' never did notify me, by a CEL, that the cat. was even missing, when indeed it is/was... lol
to give a possible explanation of this phenomenon, I suspect that you have not driven the drive cycle required to make the monitor valid.

if you want to try to turn your light on, do this.

Catalyst Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off.
- No DTCs present.
- Fuel level is between 15% and 85% full.
- ECT above 70 F.
- Engine must have run at least 90 seconds
- Engine between 1,350 & 1,900 rpm.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 30 and 45 mph for 2 minutes.
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post #7 of Old 11-12-2013, 07:56 PM
rlcii77
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Quote:
Originally Posted by ZeeJay1997 View Post

to give a possible explanation of this phenomenon, I suspect that you have not driven the drive cycle required to make the monitor valid.

if you want to try to turn your light on, do this.

Catalyst Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off.
- No DTCs present.
- Fuel level is between 15% and 85% full.
- ECT above 70 F.
- Engine must have run at least 90 seconds
- Engine between 1,350 & 1,900 rpm.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 30 and 45 mph for 2 minutes.
Wow, had no idea there were so many prerequisite conditions to meet for that to call to function... Thanks for sharing that ZeeJay1997 ! !

Sent from Lee's Samsung Galaxy Note II using JeepForum

'94 Limited ZJ (CRUSHED, kept the 5.2L, 46RH & 249 TC)
'96 Orvis ZJ
'98 Slate 5.9 ZJ (DD)
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post #8 of Old 11-15-2013, 07:08 AM Thread Starter
davidmatlack
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Join Date: Aug 2012
Location: rocky mount
Posts: 183
Suggestions for replacement Cat and Muf

Rock Auto has a wide variety of these. Any suggestions on the best OEM replacement? Same loudness?

Best- David
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post #9 of Old 11-15-2013, 07:24 AM
zjosh93
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Location: Austin
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A lot of people, myself included, have had luck finding Magnaflow cats on Amazon for less than even the RockAuto prices. I just went to Magnaflow's website and looked up the recommended universal cat for a 4.0 and made sure not to go smaller than that. I ended up with a 2.5" version. No idea what part number and it would be different with yours having a rear O2 anyway. No change in loudness really and it has passed the state emissions every year since with no issues.
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