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E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 01-21-2015, 12:42 PM
stuartgto stuartgto is offline
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Location: san carlos
 
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Mein Auto: 318ti, 335i
Another failed CA smog test

OK, I'm next. 1995 318ti/184K miles

1st smog test
/////////// 15mph // 25mph
RPM ////// 1896 // 2078
%CO2 (mea) 16.4 // 16.2
%O2 (mea) 0.0 // 0.0
HC (max) 85 // 35
HC (mea) 84 // 85 FAIL
CO (max) 0.34 // 0.33
CO (mea) 0.18 // 0.18
NO (max) 486 // 502
NO (mea) 409 // 244

So unfortunately, I have to go to a STAR station to get a smog. 2nd smog test after changing the oil, air filter and the spark plugs, with the car being run hard prior to the test. Incidentally, the tech told me that it is illegal to have the car run hard and HOT prior to the test. But I did anyway.

2nd smog test
/////////// 15mph // 25mph
RPM ////// 1900 // 2280
%CO2 (mea) 11.5 // 11.4
%O2 (mea) 5.8 // 5.8
HC (max) 85 // 35
HC (mea) 68 // 45 FAIL (Lower)
CO (max) 0.34 // 0.33
CO (mea) 0.09 // 0.10
NO (max) 486 // 502
NO (mea) 154 // 60

O2 sensor at 135K mi, 2010

How does one tell if the catalytic converter needs to be replaced?

Any and all help is appreciated. Thanks in advance
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  #2  
Old 01-21-2015, 03:22 PM
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drivinfaster drivinfaster is offline
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well your second readings are way worse than your first....

the efficiency numbers (co2) are down compared to the first, and the o2 jumped way up from the first test.

there are ways to check the cat, but will require you to go to a repair shop with a gas analyzer.



the car does not have an egr system, so the cat reduces nox. when hc and co are at their "best" readings, nox is usually at its highest point.

if you are not having any sort of drivability issue and the maintenances are where they need to be, then you could very well likely be looking at a cat. however, since cali is one of those states where they are ubber strict on this sort of thing, your options are limited and therefore, pricey.




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  #3  
Old 02-18-2015, 09:12 PM
stuartgto stuartgto is offline
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Mein Auto: 318ti, 335i
So after cleaning the MAF sensor and the throttle body with CRC products and adding AMSOIL PI Performance Improver Concentrate to the gas twice, the readings now are:

3rd smog test
/////////// 15mph // 25mph
RPM ////// 1944 // 2088
%CO2 (mea) 14.7 // 14.8
%O2 (mea) 0.1 // 0.0
HC (max) 85 // 35
HC (mea) 159 // 35 FAIL at 15 MPH
CO (max) 0.34 // 0.33
CO (mea) 0.36 // 0.10 FAIL at 15 MPH
NO (max) 486 // 502
NO (mea) 1068 // 116 FAIL at 15 MPH

I was all ready to get a cat and the muffler shop recommended the AMSOIL PI concentrate. At the test today, the technician wondered if the product should still be in the tank. I still had 1/2 tank full from my second tank of gas with it. Did it make the cat expire or do I need to run the additive out of the tank prior to testing?
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  #4  
Old 02-18-2015, 10:05 PM
u3b3rg33k u3b3rg33k is offline
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ditch the performance enhancers, and put a bunch of ISO-HEET into a fresh tank of gas and try again. or just mix it up to E20 and try again. same thing.
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Originally Posted by MeNoo View Post
Although I have nothing scientific to say, I can confidently say that it works.
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  #5  
Old 02-19-2015, 04:53 AM
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drivinfaster drivinfaster is offline
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with all that you have done, you could be looking at one of 2 possibilities, both of which are gonna be $$$


the first would be the vanos bleeding down. for whatever reason, higher nox readings are an indication that the vanos is on its way out. at least this is what i seem to have seen as a consistent cause across the board.

the second is the cat.

it could also be both. however, as i stated before, you could guess and hope to fix it, or, you could take it to a repair shop that can test the cat for you and confirm it is not functioning properly.




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  #6  
Old 03-07-2015, 04:24 PM
stuartgto stuartgto is offline
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Well, after all is said and done, a new catalytic converter was the answer. Thanks for all the help.
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  #7  
Old 03-07-2015, 05:07 PM
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drivinfaster drivinfaster is offline
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glad to hear it. did you just have it replaced, or did you get it checked first??

what were the new readings that you passed with??





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  #8  
Old 03-08-2015, 11:59 AM
stuartgto stuartgto is offline
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Mein Auto: 318ti, 335i
I did have it checked first. A mechanic used an IR temperature gun and the reading before and after the CC was barely less than 100 degrees. It is supposed to be at least 175, and mine was no where near that delta. The final readings were:

4th smog test
/////////// 15mph // 25mph
RPM ////// 1858 // 2108
%CO2 (mea) 14.9 // 14.9
%O2 (mea) 0.0 // 0.1
HC (max) 85 // 35
HC (mea) 79 // 19
CO (max) 0.34 // 0.33
CO (mea) 0.10 // 0.00
NO (max) 486 // 502
NO (mea) 78 // 9
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  #9  
Old 03-08-2015, 12:20 PM
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bliger7gz bliger7gz is offline
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Mein Auto: 1994 BMW 325is
Was the replacement cat a used one or a brand new one.
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  #10  
Old 03-08-2015, 12:42 PM
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drivinfaster drivinfaster is offline
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eeesh,...hc is *real* close...and while i understand the idea of using a temp reading of a cat, but it is not exactly something that was considered to be accurate. that is why using a gas analyzer is the only way to confirm the efficiency of the cat.

that being said, you passed, but i would still suggest performing some additional things like run some seafoam through the engine.

a new o2 sensor with a new cat is also something i strongly suggest.



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  #11  
Old 03-08-2015, 05:04 PM
stuartgto stuartgto is offline
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Location: san carlos
 
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Mein Auto: 318ti, 335i
The replacement cat was new. Magnaflow 332004. When I had the cat checked, the mechanic didn't have a gas analyzer. I will look into replacing the O2 sensor. It was new in 2010, 50K miles ago.
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  #12  
Old 03-09-2015, 11:39 PM
E36Ken E36Ken is offline
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Mein Auto: 1993 325i
One most overlooked cheap practice before the sniffer test is to do an oil change. Carbon deposit (amongst many things) in old oil can alter the readings of the tests. Or so I was told by a smog tech.
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  #13  
Old 03-29-2015, 02:35 PM
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Magna_Flow Magna_Flow is offline
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Quote:
Originally Posted by stuartgto View Post
The replacement cat was new. Magnaflow 332004. When I had the cat checked, the mechanic didn't have a gas analyzer. I will look into replacing the O2 sensor. It was new in 2010, 50K miles ago.
We're glad to hear the cat solved your problem. The smog tests here in California are brutal. That said, there are a lot of things you can do to prolong the life of your cat. One thing to be aware of is that running a high-zinc oil like a diesel oil (Rotella, Delo, etc) which many people do in their older performance cars, can kill a cat. Also, unburned fuel is a good way to kill the cat. If your car burns coolant or oil at all, they can dramatically shorten the life as well.

Definitely replace your O2 sensor, make sure everything is good and tuned up, and if you have any of the previously mentioned issues make sure and sort them out. Do that and your new cat should outlive the car.

Cheers!
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