Fu-Wa
Fuel Injection PumpNOTICE: Do not apply battery positive (B+) voltage directly to the fuel volume regulator solenoid electrical connector terminals. Internal damage to the solenoid may occur in a matter of seconds.
The engine driven fuel injection pump increases fuel rail pressure to the desired level to support fuel injection requirements. Unlike conventional port fuel injection systems, with direct injection the desired fuel rail pressure ranges widely over operating conditions. The pump receives fuel from the fuel pump (FP) assembly, increases the fuel pressure from approximately 448 kPa (65 psi) to a variable pressure up to 15 MPa (2175 psi), and delivers it to the fuel rails. The fuel injection pump is driven by a dedicated intake camshaft lobe and is located on top of the engine.
The fuel volume regulator is a solenoid valve permanently mounted to the pump assembly. The PCM commands the fuel volume regulator to meter in a specified fuel volume with each pump stroke. The PCM regulates the fuel volume entering the rail to achieve the desired fuel rail pressure.
The fuel volume regulator control is synchronous to the cam position on which the pump is mounted. The fuel volume regulator control takes into account that camshaft phasing varies during engine operation for purposes of valve control.
Fuel Injectors
NOTICE: Do not apply battery positive (B+) voltage directly to the fuel injector electrical connector terminals. Internal damage to the solenoid may occur in a matter of seconds.
The fuel injector is a solenoid-operated valve that meters fuel flow to the engine. The fuel injector opens and closes a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open.
The fuel injector is normally closed, and is operated by a 12-volt source from either the PCM power relay or fuel pump relay. The ground signal is controlled by the PCM.
The injector is a deposit resistant injector (DRI) type and does not have to be cleaned. Install a new fuel injector if the flow is checked and found to be out of specification.
Fuel Injectors - Direct Injection
The gasoline direct fuel injection fuel injector delivers fuel directly into the cylinder under high pressure. Each injector is controlled by 2 circuits from the PCM.
A boosted voltage supply, up to 65 volts, is generated in the PCM and used to initially open the injector. The injector driver controls three transistor switches that apply the boost voltage to open the injector and then modulates the current to hold the injector open. If boost voltage is unavailable, the correct injector opening current may not be generated in the time required.
The PCM contains a smart driver that monitors and compares high side and low side injector currents to diagnose numerous concerns. Each fuel injector high side circuit is paired inside the PCM with another fuel injector high side circuit. All injector concerns are reported with a single DTC per injector.
Fuel Pressure Sensor
The fuel pressure sensor (located in the fuel line near the fuel tank) provides a pressure feedback signal for the low pressure fuel system to the PCM. The PCM uses the FLP signal to determine correct operation of the low pressure fuel system.
Fuel Pump (FP) Assembly
The FP assembly contains the fuel pump and sender assembly. The fuel pump is located inside the FP assembly reservoir and supplies fuel through the FP assembly manifold to the engine and FP assembly jet pump. The jet pump continuously refills the reservoir with fuel, and a check valve located in the manifold outlet maintains system pressure when the fuel pump is not energized. A flapper valve located in the bottom of the reservoir allows fuel to enter the reservoir and prime the fuel pump during the initial fill.
Fuel Pump (FP) Assembly And Reservoir
The FP assembly is mounted inside the fuel tank in a reservoir. The pump has a discharge check valve that maintains the system pressure after the ignition has been turned OFF to minimize starting concerns. The reservoir prevents fuel flow interruptions during extreme vehicle maneuvers with low tank fill levels.
Fuel Rail Pressure (FRP) Sensor
The FRP sensor is a diaphragm strain gauge device. The FRP sensor measures the pressure difference between the fuel rail and atmospheric pressure. The FRP sensor nominal output varies between 0.5 and 4.5 volts, with 0.5 volts corresponding to 0 MPa (0 psi) gauge and 4.5 volts corresponding to 26 MPa (3771 psi) gauge. The sensor can read vacuum and may lower the output voltage to slightly below 0.5 volts. This condition is normal and is usually the case after several hours of cold soak before the vehicle dome light is turned ON. The FP assembly is energized at the same time the dome light is commanded ON. A disabled or malfunctioning dome light does not affect the FP assembly control.
The FRP sensor is located on the fuel rail, and provides a feedback signal to indicate the fuel rail pressure to the PCM. The PCM uses the FRP signal to command the correct injector timing and pulse width for correct fuel delivery at all speed and load conditions. The FRP sensor, along with the fuel volume regulator (part of the fuel injection pump), form a closed loop fuel pressure control system. An electrically faulted FRP sensor results in the deactivation of the fuel injection pump. Fuel pressure to injectors is then provided only by the FP assembly. When the fuel injection pump is de-energized and the injectors are active, the fuel rail pressure is approximately 70 kPa (10 psi) lower than FP assembly pressure due to the pressure drop across the fuel injection pump. Thus, if the FP assembly pressure is 448 kPa (65 psi), then the fuel rail pressure would be approximately 379 kPa (55 psi) if the injectors are active.
Fuel Rail Pressure Temperature (FRPT) Sensor
The FRPT sensor measures the pressure and temperature of the fuel in the fuel rail and sends these signals to the PCM. The sensor uses the intake manifold vacuum as a reference to determine the pressure difference between the fuel rail and the intake manifold. The relationship between fuel pressure and fuel temperature is used to determine the possible presence of fuel vapor in the fuel rail.
The temperature sensing portion of the FRPT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of the thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance changes the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
Both the pressure and temperature signals control the speed of the fuel pump. The speed of the fuel pump sustains fuel rail pressure which preserves fuel in its liquid state. The dynamic range of the fuel injectors increase because of the higher rail pressure, which allows the injector pulse width to decrease.
Fuel Tank Pressure (FTP) Sensor
The in tank FTP sensor or the inline FTP sensor measures the fuel tank pressure.
Heated Oxygen Sensor (HO2S)
The HO2S detects the presence of oxygen in the exhaust and produces a variable voltage according to the amount of oxygen detected. A high concentration of oxygen (lean air to fuel ratio) in the exhaust produces a voltage signal less than 0.4 volt. A low concentration of oxygen (rich air to fuel ratio) produces a voltage signal greater than 0.6 volt. The HO2S provides feedback to the PCM indicating air to fuel ratio in order to achieve a near stoichiometric air to fuel ratio of 14.7:1 during closed loop engine operation. The HO2S generates a voltage between 0.0 and 1.1 volts.
The HO2S heater is embedded with the sensing element. The heating element heats the sensor to a temperature of 800°C (1,472°F). At approximately 300°C (572°F) the engine enters closed loop operation. The VPWR circuit supplies voltage to the heater. The PCM turns the heater ON by providing the ground when the correct conditions occur. The heater allows the engine to enter closed loop operation sooner. The use of this heater requires the HO2S heater control to be duty cycled, to prevent damage to the heater.
Inertia Fuel Shutoff (IFS) Switch
The IFS switch is used in conjunction with the electric fuel pump. The IFS switch shuts OFF the fuel pump if a collision occurs. It consists of an inverted pendulum mass that is retained in a conical cone through a set of linear springs. When a sharp impact occurs, the pendulum shifts out of the conical cone, opens the circuit and shuts OFF the electric fuel pump. Once the switch is open, it must be manually reset before restarting the vehicle.
Intake Air Temperature (IAT) Sensor
IAT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The IAT sensor provides air temperature information to the PCM. The PCM uses the air temperature information as a correction factor in the calculation of fuel, spark, and airflow.
The IAT sensor provides a quicker temperature change response time than the ECT or CHT sensor.
Currently there are 2 types of IAT sensors used, a stand alone and an integrated type. Both types function the same, however the integrated type is incorporated into the mass airflow (MAF) sensor or the turbocharger intake pressure and temperature (TCIPT) sensor instead of being a stand alone sensor.
Supercharged vehicles use 2 IAT sensors. Both sensors are thermistor type devices and operate as described above. One is located before the supercharger at the air cleaner for standard OBD and cold weather input, while the second sensor, intake air temperature 2 (IAT2), is located after the supercharger in the intake manifold. The IAT2 sensor located after the supercharger provides air temperature information to the PCM to control spark and to help determine charge air cooler (CAC) efficiency.
The IAT2 sensor for speed density control systems is centrally located on the intake manifold. The IAT2 sensor measures the intake manifold temperature. The PCM uses the information from the IAT2 sensor to determine the speed density air charge and provide input for various spark control functions. The IAT2 sensor for a speed density system is integrated with the MAP sensor.
Intake Manifold Tuning Valve (IMTV)
WARNING: Substantial opening and closing torque is applied by this system. To prevent injury, be careful to keep fingers away from lever mechanisms when actuated. Failure to follow these instructions may result in personal injury.
The IMTV is a motorized actuated unit mounted directly to the intake manifold. The IMTV actuator controls a shutter device attached to the actuator shaft. There is no monitor input to the PCM with this system to indicate shutter position.
The motorized IMTV unit is not energized below a calibrated RPM. The shutter is in the closed position to prevent airflow blend from occurring in the intake manifold. The motorized unit is energized above a calibrated RPM. The motorized unit is commanded ON by the PCM initially at a 100 percent duty cycle to move the shutter to the open position, and then falling to approximately 50 percent to continue to hold the shutter open.
Knock Sensor (KS)
The KS is a tuned accelerometer on the engine which converts engine vibration to an electrical signal. The PCM uses this signal to determine the presence of engine knock and to retard spark timing.
Manifold Absolute Pressure (MAP) Sensor
The MAP sensor measures intake manifold absolute pressure. The PCM uses information from the MAP sensor to measure how much exhaust gas is introduced into the intake manifold.
The MAP sensor for speed density control systems is centrally located on the intake manifold and measures the intake manifold pressure. The PCM uses this information to determine the speed density air charge and to provide input for various spark control functions. The MAP sensor for a speed density system is integrated with the IAT2 sensor.
Mass Airflow (MAF) Sensor
The MAF sensor uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes it to cool. This hot wire is maintained at 200°C (392°F) above the ambient temperature as measured by a constant cold wire. The current required to maintain the temperature of the hot wire is proportional to the mass airflow. The MAF sensor then outputs a signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air to fuel ratio. This input is also used in determining transmission electronic pressure control (EPC), shift, and torque converter clutch (TCC) scheduling.
The MAF sensor is located near the air cleaner assembly. Most MAF sensors have an integrated IAT sensor.
Output Shaft Speed (OSS) Sensor
The OSS sensor provides the PCM with information about the rotational speed of an output shaft. The PCM uses the information to control and diagnose powertrain behavior. In some applications, the sensor is also used as the source of vehicle speed. The sensor may be physically located in different places on the vehicle, depending upon the specific application. The design of each speed sensor is unique and depends on which powertrain control feature uses the information that is generated.
Power Steering Pressure (PSP) Sensor
The PSP sensor monitors the hydraulic pressure within the power steering system. The PSP sensor voltage input to the PCM changes as the hydraulic pressure changes. The PCM uses the input signal from the PSP sensor to compensate for additional loads on the engine by adjusting the idle RPM and preventing engine stall during parking maneuvers. Also, the PSP sensor signals the PCM to adjust the transmission EPC pressure during increased engine load, such as during parking maneuvers.
Power Steering Pressure (PSP) Switch
The PSP switch monitors the hydraulic pressure within the power steering system. The PSP switch is a normally closed switch that opens as the hydraulic pressure increases. The PCM provides a low current voltage on the PSP circuit. When the PSP switch is closed, this voltage is pulled low through the SIGRTN circuit. The PCM uses the input signal from the PSP switch to compensate for additional loads on the engine by adjusting the idle RPM and preventing engine stall during parking maneuvers. Also, the PSP switch signals the PCM to adjust the transmission EPC pressure during increased engine load, such as during parking maneuvers.
Power Take-Off (PTO) Switch And Circuits
The PTO circuit is used by the PCM to disable some of the OBD monitors during PTO operation. The PTO switch is normally open. When the PTO unit is activated, the PTO switch is closed and battery voltage is supplied to the PTO input circuit. This indicates to the PCM that an additional load is being applied to the engine. The PTO indicator lamp illuminates when the PTO system is functioning correctly and flashes when the PTO system is damaged.
When the PTO unit is activated, the PCM disables some OBD monitors which may not function reliably during PTO operation. Without the PTO circuit information to the PCM, false DTCs may be set during PTO operation. Prior to an inspection/maintenance (I/M) test, operate the vehicle with the PTO disengaged long enough to successfully complete the OBD monitors.
PTO Circuits Description
The 3 PTO input circuits are PTO mode, PTO engage, and PTO RPM.
The PTO engage circuit is used when the operator is requesting the PCM to check the needed inputs required to initiate the PTO engagement.
The PTO RPM circuit is used when the operator is requesting additional engine RPM for PTO operation.
Throttle Position (TP) Sensor
The TP sensor provides a signal to the PCM that is linearly proportional to the throttle plate position. The TP sensor is mounted on the throttle body. As the TP sensor is rotated by the throttle shaft, the following operating conditions are determined by the PCM:
- closed throttle (includes idle or deceleration)
- part throttle (includes cruise or moderate acceleration)
- wide open throttle (includes maximum acceleration or de-choke on crank)
- throttle angle rate
Turbocharger
The turbocharger assembly is an exhaust driven centrifugal compressor. Expanding exhaust gases drive the turbine shaft assembly to speeds over 100,000 RPM. The turbocharger increases the power output of an engine by increasing the mass of air entering the engine.
Two types of turbocharger are currently being used.
The first turbocharger has an integrated wastegate.
The second type of turbocharger has an integrated bypass valve in the turbocharger housing.
Turbocharger Boost Pressure (TCBP) Sensor
The TCBP sensor is located in the intake air tube between the CAC and the throttle body. The TCBP sensor measures the throttle inlet pressure. The PCM uses the information from the TCBP sensor to refine the estimate of the airflow rate through the throttle and to determine the desired boost pressure. The TCBP sensor for a speed density system is integrated with the CACT sensor.
Turbocharger Bypass (TCBY) Valve
The TCBY valve(s) prevent back flow through the turbochargers when the throttle is rapidly closed to avoid undesirable noise. The high pressure downstream of the turbocharger is vented back to the intake air stream when the valve is open reducing pressure in the system.
Two types of bypass valves are currently being used. The first is a solenoid controlled valve located in a crossover tube between the turbocharger intake side and the pressurized output to the charge air cooler (CAC). The second type of bypass valve is an electropneumatically controlled system consisting of a vacuum source, control solenoid, tubing and a vacuum controlled bypass valve that is integrated into the turbocharger housing.
Turbocharger Intake Pressure And Temperature (TCIPT) Sensor
The TCIPT sensor is located in the intake air tube between the air filter assembly and the turbocharger. The TCIPT sensor measures the turbocharger intake pressure and temperature. The PCM uses the information from the TCIPT sensor to determine if the airflow to the turbocharger is being restricted by a clogged air filter or other debris. The TCIPT sensor is integrated with an IAT sensor.
Turbocharger (TC) Wastegate Regulating Valve Solenoid
The TC wastegate regulating valve solenoid allows the PCM to indirectly control the turbocharger wastegates. The TC wastegate regulating valve solenoid controls the feedback pressure to a pneumatically powered wastegate diaphragm in order to control the boost pressure limit. When the compressor outlet pressure is allowed to increase, a pneumatically powered actuator opens each turbocharger wastegate and limits compressor outlet pressure.
The TC wastegate regulating valve solenoid supplies pressure to the pneumatically powered wastegate diaphragm, which regulates the maximum boost pressure to a constant value. A pressure greater than 35.5 kPa (5 psi) on the pneumatically powered wastegate diaphragm opens the wastegate. The TC wastegate regulating valve solenoid can partially vent (reduce) the control pressure, resulting in increased regulated maximum boost.
A duty cycle of 100% vents feedback pressure to the intake air supply, eliminating any boost limit control by the wastegate. A duty cycle of 0% results in the base boost limit.
Universal Heated Oxygen Sensor (HO2S)
The universal HO2S, sometimes referred to as a wideband oxygen sensor, uses the typical HO2S combined with a current controller in the PCM to infer an air to fuel ratio relative to the stoichiometric air to fuel ratio. This is accomplished by balancing the amount of oxygen ions pumped in or out of a measurement chamber within the sensor. The typical HO2S within the universal HO2S detects the oxygen content of the exhaust gas in the measurement chamber. The oxygen content inside the measurement chamber is maintained at the stoichiometric air to fuel ratio by pumping oxygen ions in and out of the measurement chamber. As the exhaust gasses get richer or leaner, the amount of oxygen that must be pumped in or out to maintain a stoichiometric air to fuel ratio in the measurement chamber varies in proportion to the air to fuel ratio. The amount of current required to pump the oxygen ions in or out of the measurement chamber is used to measure the air to fuel ratio. The measured air to fuel ratio is actually the output from the current controller in the PCM and not a signal that comes directly from the sensor.
The universal HO2S also uses a self contained reference chamber to make sure an oxygen differential is always present. The oxygen for the reference chamber is supplied by pumping small amounts of oxygen ions from the measurement chamber into the reference chamber.The universal HO2S does not need access to outside air.
Part to part variance is compensated for by placing a resistor in the connector. This resistor trims the current measured by the current controller in the PCM.
The universal HO2S heater is embedded with the sensing element allowing the engine to enter closed loop operation sooner. The heating element heats the sensor to a temperature of 780°C to 830°C (1,436°F to 1,526°F). The VPWR circuit supplies voltage to the heater. The PCM controls the heater ON and OFF by providing the ground to maintain the sensor at the correct temperature for maximum accuracy.
Vehicle Speed Sensor (VSS)
The VSS is a variable reluctance or Hall effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low speed, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission shift scheduling, and TCC scheduling.
Wastegate Vacuum Sensor
The wastegate vacuum sensor is an absolute pressure sensor that provides the PCM an analog voltage output that is proportional to the applied vacuum. The wastegate vacuum sensor is located near the turbocharger and the turbocharger wastegate regulating valve solenoid. The wastegate vacuum sensor measures the vacuum supplied by the turbocharger wastegate regulating valve solenoid to the wastegate actuator. The PCM uses the information from the wastegate vacuum sensor to determine the amount of vacuum being applied to the wastegate actuator.
