the catalytic converter blues...

[1985bmw325e]

well, it's time for a new catalytic converter. Didn't pass smog test and when i looked at the nox reading, numbers are really close to the max. So instead of buying an oem catalytic converter worth more than my car, what other options do i have? i'm looking for reliability and a durable aftermarket catalytic converter that won't crap out on me in 3 years. People use magnaflow catalytic converters.....will i still pass smog with that type of cat?

feedback would be greatly appreciated since my registration date is coming up soon.

[bmwsmurf]

Re: the catalytic converter blues...

well, it's time for a new catalytic converter. Didn't pass smog test and when i looked at the nox reading, numbers are really close to the max. So instead of buying an oem catalytic converter worth more than my car, what other options do i have? i'm looking for reliability and a durable aftermarket catalytic converter that won't crap out on me in 3 years. People use magnaflow catalytic converters.....will i still pass smog with that type of cat?

feedback would be greatly appreciated since my registration date is coming up soon.

How do you know it's the cat and not something else (i.e. when was the O2 sensor replaced, is the fuel regulator, any vacuum leaks, are the plugs old, etc).

I did a quick search, most people say DEC or CATCO cats are the way to go. Not that expensive either!

[joecoolinatl]

Catalytic Converter NOx Emissions

Thousands of technicians have faced the challenge of bringing a particularly stubborn application into compliance for NOx emissions. High NOx readings are a clear sign of performance issues somewhere in the system. The question is, where?

Among the potential causes of non-compliant NOx readings are:

Misfire condition
Malfunctioning or improperly adjusted EGR valve
Failed oxygen sensor
Leak in exhaust tubing upstream of converter
Excessive carbon deposits in combustion chamber
Improper spark advance
Blocked coolant passage
Overly lean air-fuel mixture
Damaged cold air duct
Corroded or damaged engine sensor electrical connections

Please note that while a failed catalytic could contribute to high NOx readings, the failure in itself most likely would have been caused by some other upstream performance problem. In all cases, it is crucial to identify the root cause of the problem before blaming the poor converter. Just the process of changing the cat and not fixing the root problem will surely destroy the new converter quickly, and to make matters worse, that would not be covered under warranty.







now
as for where to buy direct fit ones (oem style, from headers back to end of cat where it meets the catback portion of the exhaust) for cheap-
some ideas for you as most of these are 300$ at most. compared to the 1100-1200+ from bmw
and personally this is what im doing to one of my e30s soon rather than cutting the pipes and putting a cheap one on)

http://www.autopartswarehouse.com/replacement_sm/bmw~catalytic_converter~replacement.html

http://www.catalyticonverters.com/bmw_325e_catalytic_converter.html

http://www.ecatalyticconverter.com/bmw-325_series-131-1987-converter.html

hope that helps :)

[reelizmpro]

You do not need to replace the entire cat with downpipes and flanges. You could simply have the muffler shop cut out the cat and weld in aftermarket Catco or Magnaflow Carsound cat. Both are high flow cats with 5 year warranty's I believe. You could find these universal cats for less than $100 too.

If you want to stay OEM, you could try to find cheaper OEM ones thru parts suppliers or gamble on a used one from another ETA.