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Old 01-31-2011, 09:22 PM   #1
Dado 540
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Join Date: Jan 2008
Location: GTA
Posts: 1,985
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, 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
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