Cooling System General Information

Introduction M56 2.5L SULEV Engine

The 6-Cylinder M56 SULEV (Super Ultra Low Emission Vehicle) is available on a limited (by state) basis in the E46/2, E46/3 and E46/4.

SULEV models (E46 sedan, coupe and sportwagon all with automatic only) will be sold in
California, New York and Massachusetts as 2003 models and in Vermont starting in 2004
model year. In addition these vehicles are certified as PZEV (Partial Zero Emissions Vehicles).

PZEV regulations include:
- Vehicles must meet SULEV tailpipe emissions standard (approx. 1/5 of ULEV standards)
- Vehicles conform to Zero Evaporative Emissions
- Vehicles subject to extended OBD regulations.
- Emission relevant components warrantied for 15 years or 150,000 miles M56 Engine.

The following components are used to achieve SULEV and Zero Evaporative Emission
requirements:
- Pistons Revised to change spark travel path.
- Catalytic Converters Ceramic carriers with high cell density for better Warm Up Control.
- Oxygen Sensors Planar wide band O2 sensors in front of the cats
- Vanos Positioning changed during start up for improved start up and emissions
- Fuel Pump Control Revised with raised pressure and more accurate flow control
- Fuel Injectors New design for improved fuel flow and higher working pressure
- Fuel System All metal fuel system components made of stainless steel
- Air Intake System Revised to block HC escape
- Crankcase Ventilation Revised
- Secondary Air System Mass air flow sensor to monitor secondary air flow
- Cooling System Revised to reduce Ozone levels.


Cooling System
The radiator of the E46 SULEV looks similiar to the standard E46 radiator. The surface of the cooling fins are coated with a special "PremAir" coating. The coating consists of multiple porous layers of a catalytic surface. The task of the catalyst coating is to convert Ozone into Oxygen.