Model: E65 - 745i / E66 - 745Li
Production Date: 11/2001 - E65, 01/2002 - E66
Manufacturer: Bosch
Pin Connector: 134 Pins - 5 Modular Connectors
Principle Of Operation
When KL15 is switched "on" the ECM is ready for engine management. The ECM will activate a ground path to energize the three Engine Control Module Relays in the IVM (see diagram on the previous page).
- The 1st ECM Relay supplies operating voltage through a fuse (in the IVM) to the ECM.
- The 2nd ECM Relay supplies operating voltage through a fuse (in the IVM) to the Fuel Injectors.
- The 3rd ECM Relay supplies operating voltage through a fuse (in the IVM) to the Oxygen Sensors.
The Ignition Coil Relay (4th relay) is energized by the CAS Module which supplies operating voltage through a fuse (in the IVM) to the Ignition Coils.
The IVM receives high amperage voltage supply from fuses F101 and F104 (100 Amp). The fuse junction is located on the right inner fender of the engine compartment (under the remote charging post). This supply is for the consumers that are controlled by the IVM internal relays.
Scheme 1
When KL15 is switched "off" the ECM operating voltage is removed. The CAS Module will maintain voltage to the Ignition Coil Relay for a few seconds to maintain ignition coil activation (Emission Optimized - introduced in 2000 MY).
Ground is required to complete the current path through the ECM. The ECM also
Scheme 2
- Internally links a constant ground (1) to the engine sensors.
- Switches ground (2) to activate components.
Scheme 3
Air flow into the engine is regulated by the Valvetronic system controlling valve lift adjustment. The intake air flow is set by adjusting the valve lift while the throttle valve is fully opened. This further improves cylinder filling and reduces fuel consumption. All of the ECM monitoring, processing and output functions are a result of regulated air flow.
The Accelerator Pedal Position is monitored by the ECM for pedal angle position and rate of movement. As the accelerator is moved, a rising voltage signal from the Hall sensors requests acceleration (and at what rate).
The ECM will request the Valvetronic control module to increase the intake valve "lift". As a result of the increased air flow, the ECM will increase the volume of fuel injected into the engine and advance the ignition timing. The "full throttle" position indicates maximum acceleration to the ECM, and in addition to the functions just mentioned, this will have an effect on the air conditioning compressor (covered in Performance Controls).
As the accelerator pedal is released (integral springs), the decrease in voltage signals the ECM to activate fuel shut off if the RPM is above idle speed (coasting). The Valvetronic control module will decrease the valve lift to maintain idle speed. The ECM monitors the engine idle speed in addition to the accelerator pedal position and Valvetronic position.
The pedal position sensor consists of two separate Hall sensors with different voltage characteristics and independent ground and voltage supply. Sensing of the accelerator pedal position is redundant. The pedal position sensor is monitored by checking each individual sensor channel and comparing the two pedal values. Monitoring is active as soon as the sensors receive their voltage supply (KL15).
The Electronic Throttle valve is operated by the ECM (supplying voltage and ground) for opening and closing based on the accelerator pedal position, engine load and intake manifold vacuum.
When the throttle valve is operated, the ECM monitors feedback potentiometers located on the actuator shaft for position/plausibility. These two sensors operate inversely (voltage values) with throttle plate actuation.
The tasks of the throttle valve are
Internal Tank Fuel Circuit Operation
The fuel pump supplies fuel from the surge chamber via the fuel filter (located next to the frame rail under the driver's floor) to the fuel injection valves. The fuel pump always pumps more fuel than the engine requires in all operating conditions. The fuel pressure regulator built into the fuel filter adjusts the pressure to 3.5 bar and feeds the excess fuel in the return flow back into the tank.
The pressure regulator valve in the return flow sets a return pressure of 1.0 - 1.5 bar. This pressure prevents fuel vapor locks in the return flow and also ensures operation of the two suction jet pumps.
The fuel flows from the pressure regulator valve on to an intersection point where the fuel return flow is split. Some of the fuel flows through the suction jet pump in the left half of the tank via the internal fuel line to the surge chamber. The suction jet pump acts like a venturi tube which draws the fuel from the left half of the tank into the right half.
The other amount of diverted fuel flows via the second internal fuel supply directly to the right half of the tank and to the second suction jet pump (21). This pumps the fuel from the right half of the tank into the surge chamber to ensure that the surge chamber is always filled with enough fuel in all driving conditions and takes full advantage of the reserve capacity .
Fuel Management delivers fuel from the tank to the intake ports of the engine. To accomplish this, fuel supply must be available to the fuel injectors. Then the fuel must be injected in the precise amount and at the correct time. The ECM does not directly monitor fuel supply, although it does control it. The ECM controls and monitors fuel injection .
Ignition Management provides ignition to the combustion chambers with the required voltage at the correct time. Based on the combination of inputs, the ECM calculates and controls the ignition timing and secondary output voltage by regulating the activation and dwell of the primary ignition circuit . The ECM controls and monitors the primary ignition circuit as well as the secondary ignition output (Misfire Detection).
The ECM has a very "broad" range of ignition timing. This is possible by using a Direct Ignition System, or sometimes referred to as "Static Ignition System". Reliability is also increased by having separate individual ignition circuits.
The Ignition Control is determined by the ECM (load dependent). The ECM will calculate the engine "load" based on a combination of the following
The dwell time will be regulated based on battery voltage. When cranking, the voltage is low and the ECM will increase the dwell to compensate for saturation "lag time". When the engine is running and the battery voltage is higher, the ECM will decrease the dwell due to a faster saturation time.
The Crankshaft Position/RPM signals the ECM to start ignition in firing order (1-5-4-8-6-3-7-2) as well as providing information about the engine operation. This input is used in combination with other inputs to determine engine load which advances/retards the ignition timing. Without this input, the ECM will not activate the ignition.
Cold start is determined by the ECM based on the engine coolant temperature and RPM during start up. A cold engine will crank over slower than a warm engine, the ignition timing will range between top dead center to slightly retarded providing optimum starting.
When starting a warm engine, the RPM is higher which results in slightly advanced timing. If the engine coolant and intake air temperature is hot, the ignition timing will not be advanced reducing starter motor "load".
During cranking, the ECM recognizes the Camshaft Position (compression stroke) and activates the ignition per cylinder (firing order).
Multiple Ignition Pulses ensure good spark quality during engine start up. The ECM will activate the ignition coils multiple times (1) per 720° of crankshaft revolution.
Scheme 4
The ignition timing will be progressively advanced assisting the engine in coming up to speed. As the engine speed approaches idle RPM, the timing remains slightly advanced to boost torque. When the engine is at idle speed, minimum timing advance is required. This will allow faster engine and catalyst warm up. The multiple pulsing switches to single pulse when engine speed >1350 RPM (varied with engine temperature).
The timing will be advanced when the ECM observes low engine RPM and increasing accelerator/air volume inputs (acceleration torque). As the Valvetronic valve lift is increased, the ECM advances the timing based on the engine acceleration request (and at what rate). The ECM will fully advance timing for the "full throttle" position indicating maximum acceleration (torque).
The Air Flow Volume signal provides the measured amount of intake air volume. This input is used by the ECM to determine the amount of timing advance to properly combust the air/fuel mixture.
The Air Temperature Signal assists the ECM in reducing the risk of detonation (ping). If the intake air is hot the ECM retards the ignition timing. If the intake air is cooler, the ignition timing will be advanced.
As the Valvetronic valve lift is decreased, the ECM decreases the ignition timing if the RPM is above idle speed (coasting). This feature lowers the engine torque for deceleration. When the engine RPM approaches idle speed, the timing is slightly advanced to prevent the engine from stalling. The amount of advance is dependent upon the engine temperature and the rate of deceleration.
Emissions Management controls evaporative and exhaust emissions. The ECM monitors the fuel storage system for evaporative leakage and controls the purging of evaporative fuel. The ECM monitors and controls the exhaust emissions by regulating the combustible mixture and after treating by injecting fresh air into the exhaust system. The catalytic converters further break down remaining combustible exhaust gases and is monitored by the ECM for catalyst efficiency .
The Evaporative Leakage Detection is performed on the fuel storage system by the DM TL pump which contains an integral DC motor that is activated by the ECM. The ECM monitors the pump motor operating current as the measurement for detecting leaks.
The DM TL generates a pressure of 20-30 mbar in the fuel tank and evaporative system. The electrical current required for this is calculated by the ECM serves as the indirect value for the tank pressure.
The DM TL carries out a reference measurement before each measurement. This is performed by building up a pressure for 10-15 seconds using an internal orifice of 0.5 mm as a reference and the ECM monitors the current required by the pump motor (20-30 mA).
If a lower pressure is detected in the pressure build-up (low current draw) as compared to the reference measurement, this indicates a leak in the fuel tank/evaporative system. If a higher pressure is detected (higher current draw), the system does not have a leak.
The pump also contains an ECM controlled change over valve that is energized closed during a Leak Diagnosis test. The ECM only initiates a leak diagnosis test every second time the criteria is met. The criteria is as follows
- Engine OFF with ignition switched OFF .
- ECM still in active state or what is known as "follow up mode" (ECM Relay energized, ECM and components on-line for extended period after key off).
- Prior to Engine/Ignition switch OFF condition, vehicle must have been driven for a minimum of 20 minutes.
- Prior to minimum 20 minute drive, the vehicle must have been OFF for a minimum of 5 hours.
- No faults in the ECM for DM TL / tank venting system.
- Fuel Tank Capacity must be between 10 and 90% (safe approximation between 1/4 - 3/4 of a tank).
- Ambient Air Temperature between -7°C & 35°C
- Altitude < 2500m (8,202 feet).
- Battery Voltage between 11.5 and 14.5 Volts
When these criteria are satisfied every second time, the ECM will start the Fuel System Leak Diagnosis Test. The test will typically be carried out once a day ie:, once after driving to work in the morning, when driving home in the evening, the criteria are once again met but the test is not initiated. The following morning, the test will run again.