New Catalytic Converter

[m3f_I M Legend]

I'm barely passing smog in my 95 so I'm pretty sure I'm going to need a new cat soon (227k).



Seems like DEC and Magnaflow are my only options but how difficult is the install?



Can anyone share their experiences?

[m3f_bluptgm3]

I’d try a fresh O2 sensor and get existing catalyst HOT before going to inspection station.


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[m3f_I M Legend]

I’d try a fresh O2 sensor and get existing catalyst HOT before going to inspection station.





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Yeah, that's what I've been doing the few times and I'm barely passing. Failed a couple times already because the they waited too long to start the test.

[m3f_egebhardt]

I would bet your smog guy isn't letting the cats get hot before the test.

My guy puts a stick on the gas pedal to 2,500rpm for 2 minutes, then runs the test within 30 seconds.

That cat is so far back there that it doesn't get hot.

New plugs, oil, fresh gas (at least 1/3 tank), pressure in the tires, clean air filter. I'm guessing you've got those covered.

I've seen a lotta guys buy new cats when the original is not yet gone. By gone, I mean those Germans put a lot of platinum and paladium in there. It takes a while before all that metal is gone unless some nil-rod has been flooring it and forcing the cats to choke on an excessive amount of unspent fuel.

[m3f_j0rdan J]

Remove your air filter. And have them place a large fan in front of your car. I know it sounds goofy, but it worked for my M3. Along with checking rear tire pressure, and making sure the tech can run the car on the dyno for a little bit to warm up the cats again.

[m3f_I M Legend]

Hey thanks for all the responses on how to pass smog but that's not my question.



I'd like to replace my cat and would like to get someone with experience in department to chime in.

[m3f_avusblu_e36]

^^ unbolt that section of exhaust, cut off the old cats, weld in the new ones? If you can't do that yourself have any exhaust shop do it

[m3f_wgknestrick]

IMO, stay away from the ceramic core cats (what most cheap, universal cats are). They aren't even worth installing as they clog up so fast. Ceramic breaks apart, etc. They are total junk IMO and if you get 2 years out of them, you are lucky. Most last about a year, esp on turbo cars.


If in CA, I'd not mess around and just get a :

Vibrant GESi OBD2 despite your car being ODB1. They are an OEM quality, high flow cat with metallic core. You could probably use a refreshening

(200K+)in your exhaust pipes anyways. Custom exhausts are so cheap around here, it's hard not to recommend, but YMMV.


You might be able to get away with Magnaflow's ODB1 metallic core cats (like I have-I'm turbo though), but I don't actually have to pass a test like you do. It's better than nothing, but I wouldn't bet on it passing 100% of the time going from what my nose tells me.