Catalytic converter rattling.....going bad.....

Discussion in 'KJ General Discussion' started by megatone, Nov 17, 2015.

  1. megatone

    megatone Full Access Member

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    Ok, so the cat on the drivers side of my 2003 Libby V6 is rattling, the computer is giving the code related to that cat being below threshold efficiency.....I removed the cat and found that it was grossly plugged up. A new Mopar cat costs $1,300 at a local dealership...so I hollow out the cat (I will buy a new one when funds allow, but in the mean time: 1-3 months ( will it be safe to run the Liberty with an empty cat?
     
  2. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    At least it wont hopefully be running rich anymore. It will effect back pressure a bit.
    Still, I think you should be ok as long as other side is ok.
    I will let others elaborate on above & the next statement, I believe you can put Walker cats in the KJ.
    May even want to do both.

    Bob seems to have had good luck with the walker cats.
    Post # 4 Link: http://www.jeepkj.com/forum/f196/catalytic-converter-help-53466/
     
    Last edited: Nov 17, 2015
  3. M38 Bob

    M38 Bob Full Access Member

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    expect the check engine light to remain on. I'd not want to run it any longer than necessary. I've had excellent results with both IMCO(now a division of AP) and MagnaFlo aftermarket converters. Are they as "loaded" with catalyst as OE? NO, but they are fully capable of turning the light off and meeting emission checks for the remaining life of most vehicles.

    At my shop I would install an aftermarket universal fit for approx $160 each. Direct fits usually double that, but any weekend grease monkey can install em.

    Bob
     
  4. tommudd

    tommudd Moderator Staff Member Moderator

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    Personally I would not drive it a week even, get new cats as soon as possible. You're going to have issues if you continue to run it that way
     
  5. M38 Bob

    M38 Bob Full Access Member

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    Tom IS right.

    Bob

    As a side note; I have scrap converter buyers come by who will really get competitive with each other to by my pull offs. Prices vary from over $150 for some imports to $2.50 for any aftermarket. these prices are for USED,JUNK converters. seems odd that those aftermarkets, with so little precious metals can perform as well as the more expensive ones.
     
    Last edited: Nov 18, 2015
  6. TheBlueKJ

    TheBlueKJ Full Access Member

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    Without the catalyst honeycomb you are going to have a SERIOUS decrease in exhaust back pressure which is VERY bad for the engine so get that new cat in there ASAP

    EDIT: to elaborate further, without that back pressure there is a high chance of sucking a valve. ex. my buddy ran his 4.7l (which is a 3.7 +2 cylinders, straight piped AFTER the cat and he still sucked a valve after awhile. Without the cat the back pressure will be even less than a straight pipe after the cat
     
    Last edited: Nov 18, 2015
  7. M38 Bob

    M38 Bob Full Access Member

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    Blue, no disrespect meant, but that's total bullschit. The industry method to actually check backpressure is to drill a hole in front of CC and hold a calibrated low pressure gauge against hole. Most run from 0 to 3/4lb, anything over 2lb is partially restricted and needs replaced.

    They need a converter in place at all times so computer can compare readings from upstream O2 and downstream O2 sensors and adjust fuel/air ratio.

    Bob
     
  8. Hockeygoon

    Hockeygoon Full Access Member

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    Agreed on both. Back pressure is not needed for the engine to run properly but flow velocity is needed - and a gutted cat isn't going to effect that.
     
  9. Hockeygoon

    Hockeygoon Full Access Member

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    Sounds more like the typical engine being run hard (I am assuming that was the point of running straight pipes) and a valve spring failed (or the keeper) - hardly an uncommon occurrence in the 3.7 or the 4.7.
     
  10. tjkj2002

    tjkj2002 Full Access Member

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    Today's OE cats flow the best out of any cat's on the market,even those so called "high flow" aftermarket cat's.Gutted or not it will not change the back pressure at all.
     
  11. Birdman330

    Birdman330 Full Access Member

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    Bingo, and I'll add its used to burn off the excess fuel and exhaust before hitting the muffler for final clean up and out the tail pipe.
     
  12. tjkj2002

    tjkj2002 Full Access Member

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    Mufflers are not part of the emission system as they do nothing for emissions.
     
  13. Birdman330

    Birdman330 Full Access Member

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    Noise emissions.
     
  14. TheBlueKJ

    TheBlueKJ Full Access Member

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    Well i take what i said back then whoops

    EDIT: after further research into the subject I get what you guys mean now. Just goes to show don't always take what the older guys in the shop say as gospel


    Sent from my iPhone using the power of children's laughter
     
    Last edited: Nov 19, 2015
  15. tjkj2002

    tjkj2002 Full Access Member

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    Yeah the cats from the last 10-15 years are not those from the late '70's and '80's which totally robbed power.
     
  16. TheBlueKJ

    TheBlueKJ Full Access Member

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    Oh and I just saw what you posted about the o2 sensor. The sensor after the cat is there to make sure the cat is working and that's it. The pcm looks at the secondary to make sure that the cat is working according to spec.


    Sent from my iPhone using the power of children's laughter
     
  17. M38 Bob

    M38 Bob Full Access Member

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    And even back then it was more on an issue in the owners mind than any real issue. UNTIL they poisoned them with leaded fuel when it was still available.

    Bob
     
  18. megatone

    megatone Full Access Member

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    Well, online......today I ordered both cats.....non Mopar units......put the expense on the credit card. Holidays are upon us, and I'm pretty much tapped out as far as hard cash is concerned.

    The Mopar units would have been $1,300 each thru the dealership. And definately the best option as far as longevity and reliabilty, however, I ended up ordering MagnaFlow aftermarket brand "direct fit" for a total cost of $550. Funny thing though:

    I can't have them sent to my house out here in California. I had them shipped to my brothers house in Nevada.......he and his family will be here for Thanksgiving celebrations next week and he will be bringing both cats with him.

    All the vendors that I contacted in my attempt to purchase the lowest priced aftermarket cats told me they are not permitted to ship cats to California. I asked why and the basic response was that thier cats are not C.A.R.B. approved. I asked what is the difference between the CARB approved units and the non CARB units.......Basically I was told that they all perform the same. The CARB and non CARB units are identical in fit and performance.....the differences have to do with a CARB environmental tax and a CARB stamp which is placed upon each taxed unit which drives the cost upwards.


    Still kinda confused about this. Oh well......I seriously doubt next time the smog tech is going to stuff his face down past the hot exhaust manifold looking for a CARB stamp on the new cats.
     
  19. CzarKJ

    CzarKJ Full Access Member

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    God I hate the republic of California.
     
  20. tjkj2002

    tjkj2002 Full Access Member

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    Actually that is false,those aftermarket cats do not perform the same as OE.


    OEM cat's are up to 95% efficient,high end "direct fit" cat's are only about 60% efficient,and those cheap $100 universal cat's are about 30% efficient.


    Those higher end aftermarket cat's will barely get a vehicle to pass emissions. Remember the check engine light does not turn for emission reasons till the vehicle passes the 1.5 times the allowable particulates.