Engine Peripheral Components/Systems
ELECTRIC THROTTLE VALVE ACTUATOR
The throttle valve assembly of the M62 TU is an electric throttle valve (EDK) controlled by an integral EML function of the ME 7.2 The throttle plate is positioned by a gear reduction DC motor drive.
Similar to the original Bosch EML 1.2 and 1.7 systems, the motor is controlled by pulse width modulated control signals providing precise plate positioning. The PWM signal is at a basic frequency of 2000 Hz.
The throttle plate position is monitored by two integrated potentiometers which provide DC voltage feedback signals to the ME 7.2.
Engine idle speed control is a function of the EDK. Therefore, the M62 TU does not require a separate idle control valve. This ME 7.2 controlled sub-system is described in the Electric Throttle System Functional Description and in the ME 7.2 Input/output signal sections further on.
HIGH PERFORMANCE PLATINUM SPARK PLUGS (NGK BKR6EQUP)
The high performance, quad electrode spark plugs introduced with the M52 TU are also used on the M62 TU and M73 TU engines. Their replacement interval is 100,000 miles.
The platinum plated center electrode with quad ground electrode design provides consistent operation throughout the entire service life of the plug. The plugs also improve cold start performance and improve idle quality.
Additionally, the High performance platinum spark plugs are approved for use in M42, M44, M50, M52, M60, M62 and M70 engines. Check TSB's for updated spark plug application chart for all BMW vehicles.
FUEL INJECTORS
The M62 TU utilizes new fuel injectors manufactured by Bosch. The injector pintle consists of a two ball seat.
The ball seat design provides a tight seal when the injector is closed preventing HC formation in the intake.
The injectors have an ohmic value of 15.5 ohms.
NON RETURN FUEL RAIL SYSTEM
The M62 TU introduces a new method of meeting Running Loss Compliance without the use of the familiar 3/2 way running loss valve.
The regulated fuel supply is controlled by the fuel pressure regulator integrated in the fuel filter. A fuel return line is located on the fuel filter.
The system provides even fuel distribution to all fuel injectors due to a balance tube connecting the feed with the end of the fuel rail. The new fuel rail does not have a fuel return line.
M62 TU EXHAUST SYSTEM
The M62 TU is equipped with two additional catalytic converters known as "warm-up converters". This configuration positions the forward mounted warm-up catalytic converters closer to the hot exhaust gasses immediately exiting the combustion chambers. The closer location heats the catalytic converters to the point of light-off faster than previous systems. Earlier light-off reduces cold start emissions by allowing the gas conversion (HC to H2O, CO to CO2 and NOx by reduction to N2 and O2) to occur more rapidly just after cold start.
The system also contains two main catalytic converters. The main exhaust gas conversion process occurs further downstream in the main catalytic converters.
OVERVIEW OF COMPONENTS:
The forward mounted warm-up catalytic converters are made of thin-wall ceramics. They are mounted in a pliable material called silicatex which isolates them from vibrations ensuring a long service life,
For their relatively small size, the catalyst volume of 878 cc provides a large conversion surface area. Use of the thin-wall ceramic design also minimizes exhaust back pressure.
Both pre-catalytic converter oxygen sensors are positioned forward of each warm-up catalyst.
The Bosch LSH 25 oxygen sensors are carried over from the M62 engine and provide the familiar "swinging" voltage signal (0.2 - max lean to 0.8 - max rich) representing oxygen content in the exhaust gas.
The main catalytic converters are also made of thin-wall ceramics. The post catalytic converter oxygen sensors are positioned just behind the main catalytic converters to monitor the catalytic converter function.
The pipes of the exhaust system up to the rear main catalytic converters are made from dual wall stainless steel. This design insulates exhaust noise as well as insulating the thermal energy in the hot exhaust gasses to light-off the converters as quickly as possible.