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Thread: Failed IL Emission Test

  1. #1
    Join Date
    Apr 2005
    Location
    IL
    Posts
    160

    Default Failed IL Emission Test

    Very depressed here ... I thought I would be in an out for this.
    It's a `93 525i with 202k miles. It's not chipped. Just replaced the airfilter 2k ago. Will need to change the oil soon.

    Here are the numbers:
    Failed HC: Composite = 0.8 gpm
    Reading = 2.37 gpm
    Passed CO: Composite = 15.0 gpm
    Reading = 14.1 gpm
    CO2 = 386.8 gpm
    NOx = 4.00 gpm

    Could a cool cat be the cause? It's not suffering as far as fuel comsumption and idle is fine, except for once and a while, but that could be from the light weight flywheel ... when I clutch, it corrects the idle. I do not know when the O2 sensor has been changed, if ever.

    Ideas, please.
    Thanks,
    Ken

  2. #2
    Join Date
    Feb 2004
    Posts
    4,894

    Default

    I would start out with O2 sensor. It could be bad cat... but O2 sensor first.

  3. #3
    Join Date
    Dec 2003
    Posts
    1,640

    Default

    You have high HC and CO too. Car's not burning all the fuel.

    I'd give it a general tune up - plugs in particular - and strongly consider replacing your O2 sensor.

    Be sure the cat is hot (no extended low speed idle) before the next test.

    Jeff
    Bellevue WA
    90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
    86 Porsche 951 - Track Toy

  4. #4
    Join Date
    Apr 2005
    Location
    IL
    Posts
    160

    Default Oh no ...

    Quote Originally Posted by Jeff N.
    Be sure the cat is hot (no extended low speed idle) before the next test.
    Jeff
    It's what I thought and afraid of ... I had it checked out because the plugs are pretty new, and it runs strong with good fuel econ.

    The cat is dead

    Any suggestions for a cat and I might as well do the headers ... any other parts?

    Nuts!
    Ken

  5. #5
    Join Date
    Feb 2004
    Posts
    4,894

    Default

    Magnaflow cat...

  6. #6
    Join Date
    May 2005
    Location
    central coast nsw au
    Posts
    1,221

    Default

    man im glad we dont have to go thru this **** in oz. no emissions testing whats so ever.

  7. #7
    Join Date
    May 2004
    Location
    Japan
    Posts
    9,250

    Default

    Start with the oxy sensor. You can test it according to the Bentley book.
    But if it has more than 60K miles, I would replace it.
    http://www.autohausaz.com/catalog/lo...Token=49835494

  8. #8
    Join Date
    Apr 2005
    Location
    IL
    Posts
    160

    Default 202k miles and tested ... it's toast.

    Quote Originally Posted by shogun
    Start with the oxy sensor. You can test it according to the Bentley book.
    But if it has more than 60K miles, I would replace it.
    I have 202k miles on it and had it tested ... it's no longer effective.

    In my searching last night, I've seen people saying that OEM BMW cats are better than aftermarket.

    Any thoughts?
    Ken

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