Worldwide Diagnostic System (WDS) (418-F224)
Principles of Operation
Exhaust Gas Recirculation (EGR) system
To maintain the standards of low exhaust emission levels required of today's engines, the EGR system on this engine is fully electronically controlled.
The EGR valve is a proportional electric motor controlled directly by a duty-cycle signal from the powertrain control module (PCM). Integrated into the EGR valve is a valve position sensor. The signal from the EGR valve position sensor allows for the precise control of the timing and the quantity of exhaust gas to be recirculated. If the EGR valve becomes inoperative or fails to close completely, the PCM will raise a diagnostic trouble code (DTC) and the instrument cluster malfunction indicator lamp (MIL) will be illuminated.
If a new EGR valve is installed. The base setting (closed position) value must be configured to the PCM. This is initiated using WDS. If the base setting is not configured to the PCM, the setting from the previous EGR valve will be used and the control function of the EGR system will be incorrect.
The EGR system is fitted with an EGR cooler. The EGR cooler reduces the temperature of the exhaust gasses being returned to the intake system. By reducing the EGR temperature, the intake air charge density is not adversely affected, so maintaining the optimum fueling characteristics.
Positive Crankcase Ventilation (PCV) system
The PCV system is made up of an oil separator chamber connected to the crankcase and valve cover by hoses.
The crankcase pressure is controlled by a diaphragm operated PCV valve built into the valve cover. As the pressure in the oil separator reduces, the diaphragm valve closes against the force of the PCV valve spring, so closing the PCV valve. As the crankcase pressure rises, the PCV valve is pushed open assisted by the PCV valve spring. This allows the positive crankcase gasses to be scavenged by the air intake system.
Inspection and Verification
- Verify the customer concern.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart