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Thread: Cat converter 320i e46 m54

  1. #1
    Join Date
    Dec 2017
    Location
    Southern Zambia
    Posts
    78
    My Cars
    320i M-Sport 2003 E46

    Cat converter 320i e46 m54

    Hi,
    Can i install a universal cat converter without compromising the engine and performance? I failed to remove one downstream O2 sensor.
    It is so tight! It's grip is gone and I just need to drop the line so it comes out. But now even my cat has been compromised.
    Recently, as i wanted to verify the issue, some metal-cracking sound came from under the car just after starting the engine. When i checked, i saw some bit of water dripping just under where the cat is. The pedal also felt lighter than usual when i reved. I'm convinced it's the bank 2 cat which gave up.
    Not yet gone to mechanic though, but will.

    So i want to gather some ideas.
    Is it fine to replace this one cat with a universal one?

    You can advise on what else you think could be done.

    I love my car. It's a 2002 320i MSport E46.

    Thank you!

  2. #2
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,933
    My Cars
    2018 BMW M240i
    Don’t rush into replacing the cat. Cats fail in 2 ways:
    - try become clogged
    - internal physical damage so that entire exhaust stream isn’t going through the catalyst.

    The first failure is identified by checking to see if there’s a pressure difference between the pre-cat sensor hole (it’s called a bung) and the post-cat bung with the engine running. Difference in pressure should be very low, perhaps 1psi. The second failure is identified by inserting an exhaust analyzing probe into the tail pipe.

    Start there.

  3. #3
    Join Date
    Dec 2017
    Location
    Southern Zambia
    Posts
    78
    My Cars
    320i M-Sport 2003 E46
    Thanks for your response.

    The methods of checking pressure seem to require the removal of sensors to measure the pressure through the holes.

    But let's say the cat is clogged. What should be done? Can it be cleaned?

    And if the cat is physically damaged, is it repairable or it requires replacing? i remember hearing a cracking sound of a metal sheet about twice. I might get under the vehicle today to see if there are any physical issues.

    If it comes to replacing, I get back to the question of whether a universal cat can do well for the engine
    In my country, we do not have emission tests. So I would not worry much about the emissions but the engine performance and longevity.

    How do you guide on these?

    Thanks again.

  4. #4
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,933
    My Cars
    2018 BMW M240i
    Yes, choking to see if the cat is clogged does require the removal of the sensors. However, replacing the cat won’t fix the sensor that won’t come out. You’ll need to heat the sensor and the header with an oxyacetylene torch.

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