Throttle Motor And Feedback Position
MDK: The MS42 ECM powers the MDK motor using pulse width modulation for opening and closing at a basic frequency of 600 Hz which positions the throttle plate. The throttle plate is also closed by an integrated return spring.
Dual potentiometers feedback the actual throttle plate position, allowing the ECM to verify correct throttle position. Dual potentiometers are used for feedback plausibility.
EDK: The MS43 ECM powers the EDK motor using pulse width modulation for opening and closing the throttle plate. The throttle plate is also closed by an integrated return spring.
Two integrated potentiometers provide voltage feedback signals to the ECM as the throttle plate is opened and closed.
- Feedback signal 1 provides a signal from 0.5v (closed) to 4.5 V (full throttle).
- Feedback signal 2 provides a signal from 4.5v (closed) to 0.5 V (Full Throttle).
Potentiometer 1 is the primary feedback signal of throttle plate position and signal 2 is the plausibility cross check through the complete throttle plate movement.
Idle Air Actuator: This valve regulates air by-passing the throttle valve to control the engine idle/low speed.
The valve is supplied with battery voltage from the ECM Relay. The Idle Air Actuator is a two-coil rotary actuator. The ECM is equipped with two final stage transistors which will alternate positioning of the actuator.
The final stages are "pulsed" simultaneously by the ECM which provides ground paths for the actuator. The duty cycle of each circuit is varied to achieve the required idle RPM.
If this component/circuits are defective, a fault code will be set and the "Malfunction Indicator Light" will be illuminated when the OBD II criteria is achieved.
Hot-Film Air Mass Meter (HFM): The air volume input signal is produced electronically by the HFM which uses a heated metal film (180°C above intake air temperature) in the air flow stream.
The ECM Relay provides the operating voltage. As air flows through the HFM, the film is cooled changing the resistance which affects current flow through the circuit. The sensor produces a 1-5 volt varying signal. Based on this change the ECM monitors and regulates the amount of injected fuel.
If this input is defective, a fault code will be set and the "Malfunction Indicator Light" will be illuminated when the OBD II criteria is achieved. The ECM will operate the engine using the Throttle Position and Engine RPM inputs.
Air Temperature Signal: This signal is needed by the ECM to correct the air volume input for changes in the intake air temperature affecting the amount of fuel injected, ignition timing and Secondary Air Injection activation. The sensor is located in the center of the intake manifold (1).
The ECM provides the operating voltage (5v) to this sensor. The sensor decreases in resistance as the intake air temperature rises and vice versa (NTC). The ECM monitors the voltage signal that varies (0-5v) as the resistance changes.
If this input is defective, a fault code will be set and the "Malfunction Indicator Light" will be illuminated when the OBD II criteria is achieved. The ECM will operate the engine using the Engine Coolant Sensor input as a back up.
Resonance/Turbulence Intake System: On the M52TU and M54, the intake manifold is split into two groups of three (runners) which increases low end torque. The intake manifold also has separate (internal) turbulence bores which channels air from the idle speed actuator directly to one intake valve of each cylinder (matching bore of 5.5mm in the cylinder head).
Routing the intake air to only one intake valve causes the intake to swirl in the cylinder. Together with the high flow rate of the intake air due to the small intake cross sections, this results in a reduction in fluctuations and more stable combustion.
Resonance System: The resonance system provides increased engine torque at low RPM, as well as additional power at high RPM. Both of these features are obtained by using an ECM controlled resonance flap (in the intake manifold).
During the low to mid range RPM, the resonance flap is closed. This produces a long/single intake tube which increases engine torque.
During mid range to high RPM, the resonance flap is open. This allows the intake air to draw through both resonance tubes, providing the air volume necessary for additional power at the upper RPM range.
The Resonance Flap is closed when vacuum is applied and sprung open. This is a unitized assembly that is bolted into the intake manifold.
The ECM controls a solenoid valve for resonance flap activation. At speeds below 3750 RPM, the solenoid valve is energized and vacuum supplied from an accumulator closes the resonance flap. This channels the intake air through one resonance tube, but increases the intake velocity.
When the engine speed is greater than 3750 RPM (which varies slightly - temperature influenced), the solenoid is de-energized. The resonance flap is sprung open, allowing flow through both resonance tubes, increasing volume.
When the flap is closed, this creates another "dynamic" effect.
- # 1 Cylinder Intake Valve open Low to Mid Range RPM (>3750 RPM)
As the intake air is flowing into cylinder #1, the intake valves will close.
This creates a "block" for the in rushing air. The air flow will stop and expand back (resonance wave back pulse) with the in rushing air to cylinder #5.
- #1 Cylinder Intake Valve closes #5 Intake Valve Open => Intake Air Bounce Effect Low to Mid Range RPM (>3750 RPM).
The resonance "wave", along with the intake velocity, enhances cylinder filling.
When the engine speed is greater than 3750 RPM the solenoid is de-energized. The resonance flap is sprung open, allowing flow through both resonance tubes, increasing volume.
- #1 Cylinder Intake Valve Open - Intake air drawn from both resonance tubes. Mid to High Range RPM (>3750 RPM)
- #5 Cylinder Intake Valve Open - Intake air drawn from both resonance tubes. Mid to High Range RPM (>3750 RPM).
The resonance "wave", along with the intake volume, enhances cylinder filling.
Suction Jet Pump: The ECM regulates the Suction Jet Pump (1) to provide sufficient vacuum for the brake booster under all operating conditions. The ECM controls the Suction Jet Pump Solenoid (2) to allow vacuum flow through.
Additional vacuum compensation is applied to the brake booster when the circuit is "deactivated" (solenoid sprung open).
Vacuum enhancement is limited to the brake booster when the control circuit is "activated" (solenoid powered closed).
Pressure Control Valve: The pressure control valve varies the vacuum applied to the crankcase ventilation depending on engine load. The valve is balanced between spring pressure and the amount of manifold vacuum.
The oil vapors exit the separator labyrinth (2) in the cylinder head cover (1). The oil vapors are drawn into the cyclone type liquid/vapor separator (3) regulated by the pressure control valve (5). The oil vapors exit the pressure control valve into the intake manifold. The collected oil will drain back into the oil pan (4).
The vapors exit the pressure control valve and are drawn into the intake manifold through an external distribution tube (2). The tube has a splice at the front to equally distribute vapors to the back.
As the vapors exit the pressure control valve, they are drawn into the intake manifold through this external tube for even distribution.
At idle when the intake manifold vacuum is high, the vacuum reduces the valve opening allowing a small amount of crankcase vapors to be drawn into the intake manifold. At part to full load conditions when intake manifold vacuum is lower, the spring opens the valve and additional crankcase vapors are drawn into the intake manifold.
- Engine Oil Vapors
- Collective Drain Back Oil
- Oil Vapors to the Intake Manifold (Distribution Tube)