The EGR module is usually composed of EGR valve + EGR cooler. The common EGR control valve is controlled by the engine computer and receives DC power from the engine computer, because the control valve is a normally closed valve.
The common EGR valve uses an internal motor to open against the spring force, and there is a position sensor inside the valve to indicate the position, do not apply external force to open and close the poppet valve. It should be noted that the EGR control valve assembly cannot be disassembled and cannot be repaired.
EGR cooler cleaning
The coolant inside the cooler will gradually form carbon deposits or quickly form carbon deposits due to the failure of other working cylinders. You can use safe solvent or mineral oil to clean the interior of the cooler, completely fill up the EGR cooler module assembly, and clean the exposed module surface Put it upwards, soak the EGR cooler for a period of time, drain the liquid in the EGR cooler,
Flush with mineral oil or solvent and dry the inside of the EGR cooler with compressed air. Shake intermittently to remove loose debris from inside the EGR coolant, and flush the coolant side of the cooler with water to reduce the possibility of solvent or cleaner entering the coolant.
Inspection of EGR cooler
Disconnect one of the cooler coolant inlet or outlet connectors and the EGR valve coolant pipe connector, connect and secure a regulator air supply hose to the disconnected coolant pipe, put the EGR cooler into the hot water tank , the EGR cooler must be completely submerged in water, apply a certain amount of air pressure, check whether there are air bubbles coming out of the cooler, and verify that the air bubbles are not caused by loose pipe joints or residual air. If the EGR cooler leaks, it must be replaced.
In addition, the content related to the EGR valve is about the more important and "expensive" catalytic converter DOC and particle trap DPF.
The oxygen catalytic converter is a cylindrical ceramic carrier with many slender channels in the middle, which can greatly increase the surface area inside the ceramic carrier. The active catalytic material is added to the ceramic surface by vacuum metallization. Harmful substances and catalytic The material will be converted when it comes into contact, and the catalyst on the surface of the ceramic body will be heated to a sufficient temperature by using the heat of the engine exhaust.
After the engine is stopped, the DOC device will still maintain high temperature for a long time, if from the turbocharger
Exported to DOC equipment, where traces of engine oil or fuel can be seen, the aftertreatment diesel oxidation catalyst must be replaced
If the unit is less than 50% clogged, the aftertreatment diesel oxidation catalyst can continue to be used. If more than 50% of the unit is still clogged, replace the aftertreatment diesel oxidation catalyst
NOTE: Use of high sulfur fuel can generate sulfate particles that can clog the unit
Incomplete combustion of diesel will produce a substance: soot. The honeycomb ceramic wall captures soot and other ash from the exhaust gas, and the process of oxidizing the collected soot in the DPF is called regeneration Regeneration
Excessive soot is filtered on the surface of the DPF, resulting in excessive exhaust back pressure. Since the DOC is an integral device, no problem can be seen from the appearance, and it can only be broken up. Under certain engine operating conditions, It will cause the catalytic converter element inside the DOC to melt at high temperature.
