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Thread: HELP ASAP- Need stock OEM catalytic converter for '95 525i to pass SMOG!

  1. #1

    Default HELP ASAP- Need stock OEM catalytic converter for '95 525i to pass SMOG!

    Hello Fellow E34 Members,

    I have 1995 BMW 525i with 206K miles and am looking for a stock OEM catalytic converter for my car to pass SMOG. If you have one or know of one that is in great condition, preferable low mileage, please let me know ASAP.

    According to my BMW dealer, the OEM catalytic converter is on back ordered due to vendor part issues.

    Long story short after 3 months dealing with my BMW Independent repair shop and now my BMW Dealer to try to pass SMOG, my dealer wants me to reinstall a stock OEM catalytic converter. My stock catalytic converter is no longer good.

    I only failed in the 25MPH test on HC. My HC is measured at 44 and the maximum is 40.

    I have replaced and performed the following service already:
    1. Motor oil
    2. Spark plugs
    3. Air filter
    4. Oxygen sensor
    5. aftermarket catalytic converter (magnaflow)
    6. fuel injection service by BMW dealer
    7. BMW dealer performed diganostic on engine and all numbers looks normal and within manufacturer specs
    8. Replaced thermostat and thermostat housing

    Please let me know ASAP. Thank you in advance!

    remuse
    Last edited by remuse; 10-28-2012 at 01:12 AM.

  2. #2
    Join Date
    Feb 2004
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    4,892

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    You are not that far off... I am suspecting you got some sort of vacuum leak. Tell your mechanic to do a smoke test on the intake/vacuum system and the evap system... fix any smoke leak. That should do the trick and alot cheaper than cat converter.

    While they are doing the smoke test... have them do the exhaust smoke test too.

    You would not have such a close reading to the maximum if your cat was dead. It would be so far off.

  3. #3

    Default

    Quote Originally Posted by Tiger View Post
    You are not that far off... I am suspecting you got some sort of vacuum leak. Tell your mechanic to do a smoke test on the intake/vacuum system and the evap system... fix any smoke leak. That should do the trick and alot cheaper than cat converter.

    While they are doing the smoke test... have them do the exhaust smoke test too.

    You would not have such a close reading to the maximum if your cat was dead. It would be so far off.
    Thanks Tiger!

  4. #4
    Join Date
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    Quote Originally Posted by Tiger View Post
    You are not that far off... I am suspecting you got some sort of vacuum leak. Tell your mechanic to do a smoke test on the intake/vacuum system and the evap system... fix any smoke leak. That should do the trick and alot cheaper than cat converter.

    While they are doing the smoke test... have them do the exhaust smoke test too.

    You would not have such a close reading to the maximum if your cat was dead. It would be so far off.
    great answer. This is why I like the e34 fourms. Logical answers.
    Thanks,

    1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment

  5. #5
    Join Date
    Dec 2004
    Location
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    Quote Originally Posted by Russell View Post
    great answer. This is why I like the e34 fourms. Logical answers.
    Hmmm... I think you mean bummernut.com / bimmer.info

    BTW: What is an intake, evap and exhaust smoke test?

    Join the Aussie
    540i LE yahoo forum

    08/88 535i e34 M30+miller MAF, 'stiens, tints & teeth!

  6. #6
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    Quote Originally Posted by genphreak View Post
    Hmmm... I think you mean bummernut.com / bimmer.info

    BTW: What is an intake, evap and exhaust smoke test?
    I understand your point. I like/appreciate all of them.
    Thanks,

    1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment

  7. #7
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    Feb 2004
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    There is a smoke machine that you connects to the system you want to check... for example, the intake/vacuum system... you would hook up the smoke machine to the vacuum port... seal up the air intake... the machine will then create smoke and under pressure... like 2 PSI... if you got leaky gasket at say fuel injectors... or intake manifold gasket.... or vacuum hoses... you will see where it is leaking. So you fix those trouble spots first and then you might see more secondary leaks until you fix them all... then you should not see any more smokes spewing out of your engine.

    Smoke Wizard is one machine you can google up and see the videos of how it works. Some but very common OBD II faults found on recents cars... can only be fixed with this machine to track down those tiny air leaks.

    Same can be done on evap/fuel system... using nitrogen or CO2 as pressure... if you got smoke leaks coming out of fuel tank or charcoal canister... any evap parts... You can only see where the leaks are with smokes.

    Exhaust system is same thing... you can hook it up to your exhaust system and see if you got leaks coming out of your muffler... joints... couplers... exhaust manifold... etc.

    Alot of equipments makers sells them... Snap On... OTC, RTI, etc... Anyone who works on modern cars need this equipment to do the job right... otherwise you will get repeat comebacks for same DTC codes.

    With a smoke machine... there is zero guesswork on where the leaks are... if the smoke spews out, you got a leak.

  8. #8

    Default

    UPDATE: Just to recap, I have a BMW 525i automatic with 203K miles that has always been well maintained. I have a Remuse muffler and the OEM silencer has been removed.

    Prior to my first few smog tests, I performed the following:
    1. Motor oil
    2. Spark plugs
    3. Air filter
    4. Oxygen sensor
    5. Aftermarket catalytic converter (Magnaflow)
    6. Removed DINAN engine chip in the DME and reinstalled stock OEM engine chip in the DME. (Dealer indicated there were no issues and impact to smog if I left the DINAN transmission chip in the car. Therefore, I left the DINAN transmission chip in the car).
    My smog test reflected the HC measured 44 out of 40 in the 25 MPH test. I failed by a factor of 4 and passed everything else.

    After speaking with two independent BMW shops, they were not sure and suggested to try this and that. Therefore, I took my car to the BMW dealer.
    The BMW dealer recommended to perform the fuel injection service. After that was performed, a smog pre-test was performed and my smog pre-test reflected the HC measured 51 out of 40 in the 25 MPH test. I failed by a factor of 11 and passed everything else.

    They then suggested to diagnose failed smog. Below are what they did and the results:
    • Scoped vehicle, no faults found.
    • Ran lambda calculation using vehicle inspection report, spec is 1.000. Vehicle reached a value of .996 at 25 MPH test which is very good.
    • Checked statuses on scope for engine voltage integrator was at 1.0, showing very little correction needed by engine control unit for correct mixture.
    • Checked all spark plugs, normal shading of light gray indicating a normal mixture pattern.
    • Checked for vacuum leaks, none found at intake system.
    • Checked 02 sensor, voltages fluxuates normally between .2 and .8 volts, which is normal.
    • Checked closed loop status, vehicle was slow to warm up to operating temperature and maintain closed loop status indicating a worn thermostat. Replaced engine thermostat engine now warms up faster and closed loop was maintained at operating temperature. After the new thermostat was replaced, a smog pre-test was performed. HC measured at 54 out of 40 in the 25MPH test. I now failed by a factor of 14 and passed everything else.
    • Checked aftermarket catalytic converter (Magnflow) and performed temperature test on catalytic converter before temp was 176 F, after catalytic converter was 191F. Spec is a 200 F plus increase in temperature after the cat. This cat only gained 15 degrees F which indicates its inability to function normally, due to it’s marginal capacity.
    • The engine performs normally and shows no sign of mixture faults, so the dealer smog technician recommended that the aftermarket cat needs to be a twin cat system as originally designed or that a factory catalytic converter be obtained and installed.

    Currently, BMW has a backorder of OEM cat for my car due vendor issues. There are non in Germany. In fact, there are 16 people on the waiting list worldwide.

    Questions:
    1. Does anyone have any other suggestions or know where I can get a good condition OEM catalytic converter?
    2. Does anyone have a picture of the OEM catalytic converter for a ’95 525i installed in their car?


    Thanks in advance.
    Last edited by remuse; 10-28-2012 at 01:20 AM.

  9. #9
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    I see what the dealer is saying... there are some made with a single cat... smallish size.. and one with a much larger more oem sized cat. Then there are the twin cats design.

    Rockauto has the Magnaflow twin cats for $412.

    Autohaus has the A&B twin cats for $362.

    The Magnaflow version seems much more better workmanship.

    Cat converter is supposed to around 500 degree.

  10. #10
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    Jan 2004
    Location
    Apex, NC
    Posts
    471

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    I don't see where you live, but I assume it's probably California. I don't know what the laws are there, but here in NC there is some thing that says that if you cannot get the car into spec after taking reasonable measures, and if the parts to fix it are not available at reasonable cost, then you can get an exemption. I'm really not sure exactly what the wording is, or if it applies to just 'antique' autos (I heard about it on the MG forum) - but it would be worth looking into.

    If I was in your situation, I'd do a fresh oil change, then take the car out and do an Italian tune-up on it (high revs, almost redline, for 2-3 minutes), then try the inspection again as fast as possible before the car cools off. But then, my car doesn't even need to be checked for smog...
    Scott
    '93 525iT 245k miles (sold, but not forgotten)
    '11 TSX Sport Wagon
    '00 328i
    '78 MGB
    '08 Saab Aero


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