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    Clogged cat, what are my options?

    I'm trying to figure out for a friend what his options are for a damn near completely clogged cat.

    The sad thing is the PO spent $1400 putting a decent new setup in the car 3 years ago, from the manifold all the way down.

    There is no emissions testing where we live, but my friend has a few ethical bones in his body... He also drives a 21 year old ix, so, it's not every bone in his body ;-)

    1. Straight pipe would be the cheapest option, yes? Does this change the exhaust sound much at all? He doesn't want it louder.

    2. A "used" cat from a local forum member.
    Would this be any better than a straight pipe in the environmental sense? Unless someone can say it JUST passed smog, a cat with 100,000 miles on it that's been sitting under an old worn car for years isn't worth much catalyst wise usually, right? (now accepting PMs for a used cat you want to sell in the NW).

    3. Take to a muffler shop, tell them to slap in a generic cat.
    Is this an option? Can a muffler shop get a good cat and weld it in? Is this child's play, or something to generally stay away from? We have little experience with the local shops. What's this likely to cost ballpark?

    4. Buy a new cat and pipes from a place like Turner ($430 + S&H), pay a shop to weld/attach one side, and bolt the other. The best/simplest option, but it also seems a shame when the car has a new pipe between the manifold and the cat already.

    Im accepting random thought here, pros and cons to each option, ect. We'll be calling shops on Tuesday, i just get a feeling when they list options, new from Turner and straight pipe aint going to be on the list. I don't know shit about exhaust systems! Help!
    -------------------------------------------------
    1989 - E30 - M20B25 - Manual. Approx 300,000+ miles - Track Rat & Weekend Fun
    2000 - E46 - M52TUB28 - Manual. Approx 130,000 miles - [not so] Daily Driver

    sigpic

    I'm looking for a Lachssilber Passenger Fender and Hood. PM if you have one or both to sell!

    #2
    Cheapest option would be to get a willing muffler shop to straight pipe it.
    It won't be too loud with a regular stock or aftermarket muffler. Just sounds a little better.
    I actually just did this this morning to a 90' iS that I have for sale. Sounds great and lack of cat is not noticeable.

    Best option may be to buy an aftermarket hi-flow 2-in & 2-out cat that are readily available for less than $100 online and have your local muffler shop integrate into your system.
    Better flowing and still doing what its supposed to do.

    E30 M3 / E30 325is / E34 525iT / E34 535i

    Comment


      #3
      How do you know it's clogged? If the motor clogged it in three years, it'll destroy an aftermarket cat in no time. By definition, the catalyst shouldn't be consumed. Sounds like he needs an O2 sensor and a tune up while you're at it.
      Originally posted by Gruelius
      and i do not know what bugg brakes are.

      Comment


        #4
        Oh, I know it's clogged. Really, I know.

        The O2 sensor shall be replaced, and there is at least one other little thing that'll be done. But my friend has only had the car for 10 months or so, and it ran like complete shit when he got it. I'm betting the cat was on its last leg when he bought it. If we think the car is running good, and he burns another cat in 3 years, we'll just deal with it :)
        -------------------------------------------------
        1989 - E30 - M20B25 - Manual. Approx 300,000+ miles - Track Rat & Weekend Fun
        2000 - E46 - M52TUB28 - Manual. Approx 130,000 miles - [not so] Daily Driver

        sigpic

        I'm looking for a Lachssilber Passenger Fender and Hood. PM if you have one or both to sell!

        Comment


          #5
          Originally posted by Teaguer View Post
          Best option may be to buy an aftermarket hi-flow 2-in & 2-out cat that are readily available for less than $100 online and have your local muffler shop integrate into your system.
          Better flowing and still doing what its supposed to do.
          After looking at what used E30 cats go for, it looks like some sort of aftermarket high flow cat is the cheapest option besides straight piping at section. A quick search for high flow reveals many different cats in the sub $100 range. If it's an unmodified M20, can we go wrong with any of them? Or do they make ones that should only be used on a little one liter car?

          Thanks for the help guys!
          -------------------------------------------------
          1989 - E30 - M20B25 - Manual. Approx 300,000+ miles - Track Rat & Weekend Fun
          2000 - E46 - M52TUB28 - Manual. Approx 130,000 miles - [not so] Daily Driver

          sigpic

          I'm looking for a Lachssilber Passenger Fender and Hood. PM if you have one or both to sell!

          Comment


            #6
            no really, wtf causes a clogged cat?
            Like what if someones car is weak on torque and shit. how would they know its a clogged cat
            m20 is plenty. im simply a drifter.
            build thread -- http://www.r3vlimited.com/board/showthread.php?t=206510

            Comment


              #7
              Originally posted by ROLLingKING View Post
              no really, wtf causes a clogged cat?
              Like what if someones car is weak on torque and shit. how would they know its a clogged cat
              An engine that runs shitty will kill a cat. In our case, it looks like something large and hard gave the cat a spanking, which probably destroyed it.
              -------------------------------------------------
              1989 - E30 - M20B25 - Manual. Approx 300,000+ miles - Track Rat & Weekend Fun
              2000 - E46 - M52TUB28 - Manual. Approx 130,000 miles - [not so] Daily Driver

              sigpic

              I'm looking for a Lachssilber Passenger Fender and Hood. PM if you have one or both to sell!

              Comment


                #8
                Originally posted by ROLLingKING View Post
                no really, wtf causes a clogged cat?
                Like what if someones car is weak on torque and shit. how would they know its a clogged cat
                Other than physical damage, the most common cause of premature catalytic converter failure is an engine that is running rich. The excess hydrocarbons in the exhaust cause overheating and partial melting of the matrix.
                The car makes it possible, but the driver makes it happen.
                Jim Levie, Huntsville, AL

                Comment


                  #9
                  Agree with jlevie, I mixed up the plug wires on a Ford 4.6L and it clogged the cats within 20 minutes. Cats dont like a missfire at all

                  sigpic1984 318i Total conversion to a DIRT race car.
                  Check out our build on facebook @ www.facebook.com/brewstermotorsports

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