Catalytic Converter: Description and Operation

M50TU:

M52:

Active Silencer:

Two catalytic converters are used for exhaust gas conversion on the M52 engine. The trimetal coated converters ensure that the levels of emissions in the exhaust are brought to the lowest possible levels.

Each catalyst incorporates an oxygen sensor at the outlet, for monitoring the efficiency of the converter. The operation of the catalyst monitoring system is explained in the MS41.1 segment of the training program.

The 328i employs an "Active Silencer" system. The rear silencer is designed to reduce noise in the low and mid-range power bands without hindering performance at the high end.

The interior of the rear silencer contains two separate resonator pipes (short and long). An exhaust flap is incorporated into the short pipe side of the silencer.

The short pipe becomes the high RPM (power) resonator pipe and the long pipe becomes the low/mid range resonator.