Replacing Catalytic Converters On E39 540i

[mrogers]

Cylinder misfires at high RPMs, loss of power, rich-running smell, and rattling in the cats has convinced me I must replace them. Since I am barely out of the federally mandated 8yr/80,000-mile catalytic converter warranty (during which BMW would have replaced them for free), I must pay for it myself. I have read A LOT of material on this, especially at the roadfly boards. Bottom line: I can spend a bundle ($1000+ that I don't really have) on BMW cats, or I can spend about $130 on a pair of quality Magnaflow cats, have a local muffler shop install them for $100 or less. Sounds like a no-brainer, but as us BMW owners know, there's risks when you start putting non-OEM parts on your car. The only potential problem I've come across so far is that in colder weather, the CE light may come on because the sensors are expecting a certain temperature inside the cats, and the Magnaflows apparently don't get quite as hot as the OEM ones. But from what I've read it doesn't happen to everyone, and most people are pleased with the results.

What I'm wondering is if anyone here has had to replace their cats, and what their experience was. Even if you haven't, let me know what you think.

[tacroteau]

I'm in the same boat man. Mine is running perfect though, just sounds like my exhaust is full of marbles. If you find a good deal, post it here, I'll do the same.

Originally posted by mrogers@Apr 26 2005, 10:26 PM
Cylinder misfires at high RPMs, loss of power, rich-running smell, and rattling in the cats has convinced me I must replace them. Since I am barely out of the federally mandated 8yr/80,000-mile catalytic converter warranty (during which BMW would have replaced them for free), I must pay for it myself. I have read A LOT of material on this, especially at the roadfly boards. Bottom line: I can spend a bundle ($1000+ that I don't really have) on BMW cats, or I can spend about $130 on a pair of quality Magnaflow cats, have a local muffler shop install them for $100 or less. Sounds like a no-brainer, but as us BMW owners know, there's risks when you start putting non-OEM parts on your car. The only potential problem I've come across so far is that in colder weather, the CE light may come on because the sensors are expecting a certain temperature inside the cats, and the Magnaflows apparently don't get quite as hot as the OEM ones. But from what I've read it doesn't happen to everyone, and most people are pleased with the results.

What I'm wondering is if anyone here has had to replace their cats, and what their experience was. Even if you haven't, let me know what you think.

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[///Matt]

rogers.... If it is as you described, then you cat is defenitely fried. I'd have to reccomend OEM or you will get tons of CE lights. With that too, you could throw your DME's adaptation values out of wack which can rob you of performance and MPG's...go Boilermakers,

Regards,