Exhaust System: Description and Operation

Drive





The (E83) X3 SAV is available with the following engine and transmission variants in the US market:
The vehicles are all fitted with the VAG 174 front axle drive.

Drive Modifications


The following modifications have been made to the engine for use in the (E83) X3 SAV:
^ Modified Belt Drive the position of the deflection pulley on the alternator (150 A Bosch/Valeo) has been modified slightly.
^ M54B25 manual and automatic transmission and M54B30 manual transmission equipped vehicles use Siemens MS45.0 engine management system. This system is LEV emission compliant.
^ M54B30 automatic transmission equipped vehicles use Siemens MS45.1 engine management system. This system is ULEV II emission compliant.

Exhaust System





The following exhaust system is used at the start of (E83) X3 SAV series production:
The (E83) X3 SAV exhaust system is made of stainless steel. The exhaust system connected to the M54 engine is one piece from the exhaust manifolds to the rear silencer (muffler). However, the system is available in sections for service replacement.
As on current BMW M54 engines, each exhaust manifold is equipped with metal base catalytic converters, 2 precatalyst and 2 post catalyst oxygen sensors.
The rear silencer is equipped with an exhaust flap (similar to the E46 (3 series). It reduces noise in the lower engine rpm range. The exhaust flap is operated by a Diaphragm (4). It is controlled by a solenoid valve, which is controlled in turn by the ECM (DME). The rear silencer has an 18.5 liter volume.

Cooling System
This section describes the cooling module installed in the (E83) X3 SAV in conjunction with the M54B25 and M54B30. The following components of the cooling module were adopted from the E46 (3 series) and (E85)Z4) Z4:
^ Module carrier
^ Fan
^ Transmission oil cooler (oil-water heat exchanger)
^ Expansion tank.


The following components were physically modified for use in the (E83) X3 SAV:
^ Radiator performance increased
^ Fan shroud
^ A/C condenser performance increased
^ PS cooler performance increased





Cooling Module Components