installing catalytic convertor backwards - JeepForum.com
 
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post #1 of 10 Old 10-21-2016, 06:12 PM Thread Starter
brad88yj
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installing catalytic convertor backwards

My cat was rusted had holes and after removing found the honeycone inside is broken and chunks are rattling around inside it. I was able to find a person parting out same make etc jeep and they sold it to me. Problem is the cut it really short. The best way i can see to weld it in is to put it with the 02 facing the front of the car rather then where it originally was in rear. Will this cause any issues to put in this way?

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post #2 of 10 Old 10-21-2016, 08:52 PM
ZeeJay1997
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Dont put another cat on it until you figure out what's causing the misfires. Rich exhaust kills cats.


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post #3 of 10 Old 10-22-2016, 05:16 AM Thread Starter
brad88yj
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Quote:
Originally Posted by ZeeJay1997
Dont put another cat on it until you figure out what's causing the misfires. Rich exhaust kills cats.
without the cat on it doesn't want to idle.
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post #4 of 10 Old 10-22-2016, 06:29 AM
Timo_90xj
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Not having a cat installed should have absolutely zero effect on your Jeep idling, issue is somewhere else.

As for the cat being backwards you will most likely get a CEL, because the after-cat (downstream) O2 sensor is sniffing if the cat converter is working. With the sniffer O2 sensor before the cat, PCM thinks cat is broken and will light up the CEL for high emissions.

It won't affect how your engine runs, because only the upstream O2 sensor is coupled to the air/ fuel ratio tuning.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

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1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #5 of 10 Old 10-22-2016, 08:47 AM Thread Starter
brad88yj
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The reason why I'm asking is as shown in another of my threads I am having issues misfiring when it rains. I knew cat was bad so I cut it out put the new used one in started it up and it ran awful for a minute then back fired thru the top of motor and now won't run unless I pour gas directly into throttle body?
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post #6 of 10 Old 10-22-2016, 09:13 AM
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Do you have the upstream o2- sensor connected, is it in good condition, and are the o2- sensor wires good?
Your issue has nothing to do with the cat (unless is it's almost fully clogged), this is a sensor/ fuel/ spark/ timing issue.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #7 of 10 Old 10-22-2016, 03:00 PM Thread Starter
brad88yj
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All wires and sensors are good. I think it may be the intake manifold gasket. Maybe its sucking air at the rear and causing the misfires?
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post #8 of 10 Old 10-23-2016, 05:00 AM
ZeeJay1997
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Quote:
Originally Posted by brad88yj View Post
Maybe its sucking air at the rear and causing the misfires?
Not gonna happen. Can't get there from here.


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post #9 of 10 Old 10-23-2016, 05:10 AM
Timo_90xj
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If you had an intake manifold gasket eak, you'd be listening to plenty of whizzing sounds from the engine. No, I really don't think that is the reason. Intake manifold gasket leak on the Magnum V8s often also causes coolant to mix with engine oil, and/or engine to suck in coolant.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #10 of 10 Old 10-27-2016, 04:39 PM Thread Starter
brad88yj
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Quote:
Originally Posted by Timo_90xj View Post
If you had an intake manifold gasket eak, you'd be listening to plenty of whizzing sounds from the engine. No, I really don't think that is the reason. Intake manifold gasket leak on the Magnum V8s often also causes coolant to mix with engine oil, and/or engine to suck in coolant.
Well I've started pulling off intake just in case because whenever it would rain and started backfiring if I gave it a lot of gas to keep going my heat would switch to defrost as if I had a vacuum leak, I would also smell coolant whenever this backfire scenario would occur and gas mileage would drop bad! I'm doing all I can think. If any other ideas suggestions are appreciated!
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