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7 Series / 8 Series
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  #1  
Old 05-28-2009, 05:34 AM
shmoo235 shmoo235 is offline
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Location: NYC Suburb
 
Join Date: May 2009
Posts: 2
Mein Auto: '96 741i
Catalytic converter 740

Hey all....first post nice to be here....I just picked up a '96 741i that is in need of a new cat......any ideas for sources and or things to look out for in purchasing. I was told by a friend that there are appropriate sizes for specific models and sometimes smaller units are installed to save money which seems to be the case here.......thanks in advance
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  #2  
Old 05-29-2009, 09:30 AM
balance balance is offline
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Location: NC
 
Join Date: Feb 2009
Posts: 766
Mein Auto: 97 740iL
I read on another forum where people put magnaflow model #94105 and it worked for them, so when I got a cat code I went ahead and ordered 2 of them. Two days after I put them on I got a code for bank 1, and the next day I got a code for bank 2. About a week ago I went to a shop that specializes in bmw and the guy told me to try GMP performance cats. I havent checked them out yet but the website is www.gmpperformance.com and the phone number is 888-488-2028. By the way, these cars seem to be pretty picky about the parts you put on them, so before you start picking up $70 cats like I did, do your research.
  #3  
Old 09-13-2009, 05:55 PM
Sam Neubia Sam Neubia is offline
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Location: South Carolina
 
Join Date: Sep 2009
Posts: 1
Mein Auto: 1997 740il BMW
shmoo235/balance, I had same problem with cats and replace them twice with short ones and after markets, which became very expensive. Reason was told that cats were going bad along with check engine light giving me codes like bank 1 to bank 2, oxygen sensors. Nothing worked for my check eng. light but car runs great. Mechanic told me they could not find anthing wrong according to a computer diagnosis, just drive the car unless a problem present itself. Just recently went to dealership for the car with light on to find out a faulted cam sensor needed replacing and was told this would solve the issue, it did not. Now light is back on after a half of grand spent. Be careful about car
  #4  
Old 09-13-2009, 09:07 PM
balance balance is offline
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Location: NC
 
Join Date: Feb 2009
Posts: 766
Mein Auto: 97 740iL
Well, I was just trying to get the car ready for inspection so I checked on a couple BMW forums and thats where I saw some stories about how magnaflow cats work on these cars. I guess other people have had more luck with them than I have, but I managed to get the car inspected anyway.

Honestly I could care less about the CEL as long as the car is running perfectly, you South Carolina guys have state inspections yet?
  #5  
Old 10-06-2009, 08:15 AM
zaleonardz zaleonardz is offline
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Location: South Africa
 
Join Date: Sep 2009
Posts: 243
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Mein Auto: E65,E34, Firebird
I sometimes get jelous with the amount of parts you guys have at your fingertips, and that takes me weeks to import into South Africa, I waited 3 months for a workshop manual for my pontiac once, but then we do not have these regulations, nor CC tax, nor conjestion tax, nor luxury tax... so I guess its not all that bad
  #6  
Old 10-13-2009, 02:46 PM
97E38Bimmer 97E38Bimmer is offline
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Location: florida
 
Join Date: Aug 2009
Posts: 5
Mein Auto: 1997 bmw 740i
Catalytic Converter

The first thing to remember is that when the MIL is on (check engine, service engine, service engine soon, etc), the computer is in fact DOING it's job. Very seldom on one of these vehicles will you have a faulty computer (PCM, ECM, etc.) If the MIL is illuminated, DON'T TAKE IT LIGHTLY!! This can't be over-stressed enough. I have a 1997 740i with bad cat's. The first to note is the importance of a diagnostic check with a capable scanner. Once this is done the next step is interpreting the information revealed. This is not always simple. However in this case, if you are getting codes from bank 1 sensor 2, bank 2 sensor 2 (respectively) chances are that you have bad cat's. There are many reputable COMPANIES out there willing to sell you a converter that will fit and perhaps enhance the performance of the vehicle (respectively). However, understanding the way a converter is designed (internally) is the key to picking the right one. ******************.com can point you in the right direction. They have several listed as universal fits and a few listed as OEM replacements. Part# EAST82565 (Eastern Catalytic) should work fine and turn the MIL off. That is the least expensive route as far as purchase goes. The next step is finding a reputable shop to do the work CORRECTLY.

Don't forget that O2 sensors may also need to be replaced. Remember, the computer is doing it's job when the MIL is illuminated. When the MIL is on, the computer has basically substituted values to enable the vehicle to make it the repair shop in "limp home" mode to be repaired. Many people think that as long as the car is not running dramatically different, it's o.k. to drive. IT'S NOT!!!! That is, without causing further damage!

Last but not least, the thing to remember is that something upstream of the cat's caused the failure. Most converter failure can be narrowed down to poor of failed ignition components (spark plugs, ignition wires, etc.) In other cases, you may have a fuel delivery problem (fuel pressure regulator, fuel pump, etc). And surprisingly enough a severly clogged air filter can cause this as well.

One more thing to consider is the fact that since converters are so expensive, make sure that it is in fact the converter and not the O2 sensors themselves (which in this case it is mostly likely the converters). Here in Florida, catalytic converter replacement goes up significantly after heavy downpours and ignorant drivers make it a point take their car undercarriages for a swim in standing "lakes" on city streets. There is a lot of technical info to understand about this all but rare phenomenon but not enough time. Simply put, converters and O2 sensors don't like, and frankly are not designed to be exposed to this type of PROLONGED abuse.

I hope you find these tips helpful. Remember, be good to your bimmer and it will be good to you!

Last edited by 97E38Bimmer; 10-13-2009 at 03:00 PM.
 

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