Exhaust Gas RECIRCULATION (EGR) High Pressure (Hp) Components - EU4 And NAS Only
| ITEM | DESCRIPTION |
|---|---|
| 1 | Charge air temperature sensor |
| 2 | EGR vacuum actuator |
| 3 | High Pressure (HP) EGR cooler bypass valve position sensor |
| 4 | HP EGR valve and motor |
| 5 | HP EGR cooler |
High Pressure (HP) EGR components fitted to EU4 and NAS vehicles comprises a HP EGR valve and an HP EGR cooler.
The HP EGR valve and cooler are located on the left side of the engine. Both components are attached to the intake manifold with bolts.
The HP EGR valve is a solenoid operated valve which is controlled by the PCM. The PCM uses the HP EGR valve to control the amount of exhaust gas being re-circulated in order to reduce exhaust emissions and combustion noise. The HP EGR is enabled when the engine is at normal operating temperature and under cruising conditions.
The EGR valve receives a 12V supply from the PCM and is controlled using a PWM signal. The PWM duty signal of the solenoid ground is varied to determine the precise amount of exhaust gas delivered to the cylinders.
The HP EGR valve is operated through its full range at each engine shut down, to clear any carbon deposits that may have built up whilst the engine was running.
In the event of a failure of the HP EGR valve, the EGR function will become inoperative. The PCM can monitor the HP EGR valve solenoid for short circuits and store fault codes in the event of failure. The EGR valve can also be activated for testing using an approved diagnostic system.
The HP EGR cooler has a vacuum operated valve to direct exhaust gases through the cooler. The vacuum is controlled by the PCM using an EGR cooler bypass valve solenoid located above the cooler.
The outlet from the HP EGR cooler is fitted with a Negative Temperature Coefficient (NTC) charge air temperature sensor. The sensor is located in a threaded port on the cooler outlet to the intake manifold.
The PCM supplies the sensor with a 5V reference voltage.
The ECT sensor circuit consists of a voltage divider which incorporates an NTC thermistor within the charge air temperature sensor. The input to the sensor is a 5V reference voltage supplied through a resistor within the PCM. The ground from the sensor is also connected to the PCM which measures the voltage across the sensor which is relative to the charge air temperature.