Anyone use an aftermarket catalytic converter?

[Jon K]

Car failed PA emissions today. Safety-wise its perfect, but emitted too many NX and Hydrocarbons. He thinks my cat might be done. I've 160k miles on a 1992 M50 525i. So, now I am eveluating what to do. Has anyone used an aftermarket catalytic converter? Such as Magnaflow? I need help here guys.

[Tiger]

Get proper diagnosis first! Don't just assume bad cat... cat goes bad only if something goes wrong with engine.

[Kalevera]

Is the sucka rattling?!

[Karl]

You're getting conflicting signals here--High Nx generally means lean and high Hc or CO means rich. I think you need a better diagnosis, as Tiger said
The catalyst can wear out with time, especially with a lot of stop and go driving where the car never really warms up and stays rich, or if the O2 sensor has worn out, which will also generally cause it to run rich. Rich condition will cause the cat to run hot so the ceramic matrix breaks down. I saw one once where the guy's conversion had been running with no o2 sensor. The innards were completely blown out of the cat shell. My Chevy hauler went the other extreme, the cat got plugged up--but that's easy to diagnose with a pressure gage to the exhaust manifold.

Anyway, back to your original question, I've used aftermarket cats in two cars--but niether was BMW. If it fits, it should function OK.

[Alan_525i]

Sorry buddy, but I chuckled a bit when I read this.

Who are you having do your inspection? If you need to find someone else to do it ::wink, wink:: let me know.

If it is the cat, I seem to remember BMA having good prices on BMW cats. Much cheaper than anyone else I think.

How high were you?

[willobmw]

I'm definitely going the Magnaflow route when the time comes. Has your time come? Sounds like maybe not yet. LOL.
Willo

[Tiger]

Not quite that simple... generally what you said is right... but the relation of NOx to HC is still related... higher HC also means higher NOx... I have played around with this and the higher my HC, the higher NOx went... NOx is also controlled by the EGR system... so the diagnosis is not quite so simple.

[Jon K]

Sorry buddy, but I chuckled a bit when I read this.

Who are you having do your inspection? If you need to find someone else to do it ::wink, wink:: let me know.

If it is the cat, I seem to remember BMA having good prices on BMW cats. Much cheaper than anyone else I think.

How high were you?

Alan, I need someone to do it... wink wink at me.... seriously. BMA wants $700 for the cats... i think not.

[Elekta]

I got my 530iT cat replacement with TXDOT approved cats cut in for $500 total including tax. Find a reputable indy and have him put in his DOT spec cats, and get on down the road. This frees up money to get the 02's done at the same time.

In austin it was Muffin Muffler. No muff too tuff as they say around there. He said there is no difference except the price, and his shop's been around for 25 years...he's done all of my vehicles since 82.

Get your 02's from Patrick and do it all at once for less than it would cost to buy OEM cats and have them shipped to your house.

I sleep real well at night too.. :)

[Jon K]

I got my 530iT cat replacement with TXDOT approved cats cut in for $500 total including tax. Find a reputable indy and have him put in his DOT spec cats, and get on down the road. This frees up money to get the 02's done at the same time.

In austin it was Muffin Muffler. No muff too tuff as they say around there. He said there is no difference except the price, and his shop's been around for 25 years...he's done all of my vehicles since 82.

Get your 02's from Patrick and do it all at once for less than it would cost to buy OEM cats and have them shipped to your house.

I sleep real well at night too.. :)


I've done my O2 sensor. I am not looking to spend $500 for a catalytic. I am looking for an aftermarket, Magnaflows being about $100 ea.

[Elekta]

$500 was for two cats, installed, with tax and cat disposal charge. Mine very well could have been magna flows too. To cut them in and weld them professionally isn't cheap if you want a high level of confidence in the work.

YMMV

[Jon K]

$500 was for two cats, installed, with tax and cat disposal charge. Mine very well could have been magna flows too. To cut them in and weld them professionally isn't cheap if you want a high level of confidence in the work.

YMMV


A local shop advertises Magnaflow catalytics for $120 welded in. I am visiting them when I have spring break.