BMW M56

Engine type
2.5 Liter Six Cylinder Engine (M56 SULEV)The M56 is a re-engineered M54 engine to meet stricter emission requirements. Exclusively in the US.

Models
From 2003 to 2005 - 325iA (E46) sedan, coupe and sport wagon with automatic transmission.

Market
Sales of this model started in 2003. The E46 SULEV has only been sold in 4 states in the US.California, New York, Massachusetts and later in 2004 in Vermont.

Specs of the M56 engine - (From BMW note to dealers)

- HC block in the air intake system:
Hydrocarbon escape via the intake system is preventeddue to the use of an additional carbon filter (1)incorporated in the air filter housing and a "closed"throttle valve actuator (2).

- Fuel system components:
All metal fuel system components (fuel rail (1),injectors (2), tank ventilation valve (3), etc.) are madeof stainless steel and are fastened together usingcoupling type connectors (4).

- Fuel tank and tank ventilation system:
The fuel tank (1), tank filler neck (2) and evaporativecanister (3) are made of stainless steel.

- Crankcase ventilation system:
The crankcase ventilation valve (1) is incorporated inthe aluminum cylinder head cover (2).

- System components used to achieve SULEV tailpipe emission requirements:
(1) Dual down stream catalytic converters
(2) "Warm up" catalytic converters – high cell densitytechnology
(3) Upstream oxygen sensors – wide band technology
(4) Pistons – only 3mm fire land
(5) VANOS – set to fixed position during start up forimproved engine start
(6) New style fuel injectors–4 hole design (5 bar fuelpressure)

Secondary air system with secondary air mass flowsensor (1) used for improved monitoring of secondaryair flow.

In addition SULEV models also incorporate a "Direct Ozone Reduction System". The external heatexchange surfaces of the radiator are coated with a catalyst which reduces the ozone in the ambient airdrawn through the radiator.