maXbimmer Forums - View Single Post - Anyone using aftermarket Catalytic Converters

Dado 540 · 01-31-2011, 08:22 PM

Is anyone here using any aftermarket catalytic converters on their E39 540i

I read up some guys running Magnaflow high flow cats on bimmerforums.com, but im not sure if its gonna pass emissions test for us here in canada. They are actually improving performance.

Im experiencing a missfire at cylinder 4 only when car is given a pedal to the floor (High rpms and higher speed). Check engine starts to flash a few times and then remains on. Once i turn the engine off and them back on everything runs smooth. I swapped out the ignition coil at RMP however the symptom is back, rulling out the faulty coil.

Reading up a bit on these symptoms leads towards a clogged cat or even a faulty O2 sensor. The only code that does come up is the missfire cylinder 4.

Comments and suggestions are always welcome.

01-31-2011, 08:22 PM	#1
Dado 540 6th Gear Member Join Date: Jan 2008 Location: GTA Posts: 1,972 Car: BMW 540i	Anyone using aftermarket Catalytic Converters Is anyone here using any aftermarket catalytic converters on their E39 540i I read up some guys running Magnaflow high flow cats on bimmerforums.com, but im not sure if its gonna pass emissions test for us here in canada. They are actually improving performance. Im experiencing a missfire at cylinder 4 only when car is given a pedal to the floor (High rpms and higher speed). Check engine starts to flash a few times and then remains on. Once i turn the engine off and them back on everything runs smooth. I swapped out the ignition coil at RMP however the symptom is back, rulling out the faulty coil. Reading up a bit on these symptoms leads towards a clogged cat or even a faulty O2 sensor. The only code that does come up is the missfire cylinder 4. Comments and suggestions are always welcome. __________________ E39 540i Sport