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Thread: Catalytic converter

  1. #1
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    Catalytic converter

    Ive got a bad engine vibration when I decelerate and sometimes when I accelerate. Just replaced driveshaft a couple of weeks ago so ive ruled that out. Got a mild egg smell. Anybody ever experience this?

  2. #2
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    as you changed the driveshaft a couple of weeks ago, check the wires of the O2 sensors, once one of my wrenching buddies bought O2 sensors with too long wires and these twisted around the driveshaft and were damaged.
    Rotten egg smell, there was a SI of BMW and Audi, to change the fuel brand, I posted that here years ago https://www.bimmerforums.com/forum/s...ke-rotten-eggs
    ROTTEN EGG SMELL FROM CATALYTIC CONVERTER
    The sulphur smell from the exhaust, is actually caused by running the engine/cat convertor slightly lean for long periods and then running under a rich condition (ie going up a hill under heavy load) This is when the sulphur smell (rotten egg) is produced.
    Under relatively lean conditions, the sulphur found in gasoline is converted to sulphur trioxide, then during the rich running condition the sulfur trioxide is converted into hydrogen sulphide (rotten egg smell) within the catalytic converter. Audi of America issued a service bulletin Group 24, #92-04 which detailed this problem. They list the cause as : the gasoline sulphur content and the characteristic of catalytic convertor to store sulphur compounds and release them during rich engine running conditions.
    Switching gasoline brands may help. The Oxygen sensor may also need to be replaced to correct a fuel injection mixture problem.
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
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    Im going to check tomorrow the O2s. If I did cross the wires could that cause the vibration? Vibration seems to diminish some after I put some miles on it, not as aggressive. Got my driveshaft from Bimmerworld.

  4. #4
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    in case you crossed the O2 wires, it should run always bad, that is from my experience when we had such a case on a friends car.
    For me it sound like the center bearing, maybe not pre-tensioned http://bmwe32.masscom.net/sean750/dr...terbearing.htm
    Last edited by shogun; 12-20-2019 at 08:38 PM.
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  5. #5
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    Just to be sure on O2 plugs. Bank 2 goes to the bottom connector and Bank 1 goes to the top?

    - - - Updated - - -

    Just to be sure on the O2 plugs, bank 1 goes to the top connector at the transmission and bank 2 at the bottom?

  6. #6
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    yes, here are pics. If they are connected wrong, the left cable is tight and the right one sags/lose http://infinitier.ddo.jp/e32/page/ma...inte_50707.htm
    One can also test each one on the DMEs, I Posted that years ago http://www.bimmerboard.com/forums/posts/622383/
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  7. #7
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    Quote Originally Posted by shogun View Post
    For me it sound like the center bearing, maybe not pre-tensioned
    Can I ask what you mean by pre-tensioned?

    I had mine replaced by a shop last year and I get a weird feeling under heavy acceleration (like up over 4k RPMs) almost like a slight wobbling of the rear end. I've chalked it up to 30+ year old rear subframe mounts and bushings, but you've got me wondering if they did anything wrong...

  8. #8
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    CSB pre-load/pre-tension explained here https://www.bimmerforums.com/forum/s...0-CSB-pre-load
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  9. #9
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    Pre tension is good. Driveshaft I purchased is defective. Put old drive shaft back in and the problem went away. Got another driveshaft coming.

  10. #10
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    Just found some interesting info about thesting the cats, just in case someone wants to test https://www.bimmerforums.com/forum/s...ytic-converter
    Shogun tricks and tips for the E32 series are HERE!

  11. #11
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    I had to send my driveshaft back to Bimmerworld because it was out of balance. They told me they would correct the problem. Bimmerworld uses a shop in Arizona called Beyers and they called me to tell me that indeed the driveshaft was out of balance and they would rebalance it and get it back to me quick. I received the corrected driveshaft and installed it only to have vibration at 50mph and its horrible over 90mph. My original driveshaft has a defective front U joint and shudders at 2000 rpm, then goes away. Anyone out there know of a good vendor for driveshafts?

  12. #12
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    I've never needed this service, but I'll throw this in here. I get the Roundel magazine from the BMW Car Club every month for more then 10 years. I don't remember an issue that didn't have a small advert for this company. Might want to check out their website and see what you think.

    https://driveshaftrepair-norcross.com/
    1990 735I (Auto) E32 Feb 1990 to Present
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  13. #13
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    I've used DriveLine Service of Portland probably 15 years ago for my e23. Worked perfect out of the box.

  14. #14
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    I appreciate all of the input Ive received. Ive also shopped extensively online for driveshafts. This has been a horrible experience. Ive had to remove and replace the driveshaft 4 times and Im back at square 1. My old driveshaft, with the stiff/lumpy u joints, is smoother than the reman I got from bimmerworld. Bimmerworld uses a vendor out of Arizona called Beyer Motor Werks to rebuild there driveshafts. At this moment im trying to get my money back. Beyers claiming "something must of happened during the shipping process". Really! 2 times! So im waiting on a return shipping lable, my refund and Im going to get one from BMW. I fell like Ive been pistol whipped.

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