Egr Valve
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What Chain Reactions Will Be Caused By Water Channeling In Egr Valve?

What Chain Reactions Will Be Caused By Water Channeling In Egr Valve

It is a big topic for lack of power, involving oil circuit, circuit, gas circuit, post-treatment, etc. I believe that you masters have a headache when the maintenance power is insufficient. Next, through a case, let’s see how the light truck is handled when the power is insufficient of egr valve?

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Driver feedback: the vehicle has slow speed-up and insufficient power, and black smoke will appear during operation. The troubleshooting steps are as follows of egr valve:

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  • 1. Use the diagnostic expert to read the fault code and report the fault code.
  • P0406: the signal voltage of EGR valve position sensor is higher than the upper limit;
  • P1503: the voltage of remote accelerator pedal potentiometer 1 is lower than the minimum value;
  • P1504: the voltage of remote accelerator pedal potentiometer 2 is higher than the maximum value;
  • The EGR valve of this engine is of motor type. The high signal voltage of the position sensor is generally caused by the burning of the position sensor module caused by water inflow in the EGR valve, or the open circuit of the power supply, ground wire and signal wire of the position sensor.
  • Remote accelerator pedal related fault code because this vehicle does not have a remote accelerator, it also reports a remote accelerator fault code, which may be a calibration problem or data problem.
  • After the problem is solved, the remote accelerator pedal can be calibrated as not installed! (provided there is no short circuit in the harness of the remote accelerator pedal) the key troubleshooting direction remains at the EGR valve.
What Chain Reactions Will Be Caused By Water Channeling In Egr Valve (4)
What Chain Reactions Will Be Caused By Water Channeling In Egr Valve (5)

2. Remove the EGR valve circuit board to see if it is burned. After removal, it is found that the position sensor module inside the EGR valve is indeed burned and there are water traces. There are two possibilities.

1: Condensate after EGR valve high temperature;

2: The EGR valve cooler is damaged, causing the water in the EGR valve cooler to flow into the EGR valve;

Replace the EGR valve and investigate where the water comes from.

3. Since there is water trace, remove the EGR cooler for water test to judge whether the water outlet is condensate or cooler leakage!

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  • After removing the cooler, plug one end of the cooling water pipe. The other end inflates the air inside with an air pump to see if the air in the cooler blows bubbles.
  • If yes, it indicates that the cooler does have water leakage. If not, it indicates that it is normal. After the pressure test, it is found that there is no obvious air leakage, indicating that the cooler is normal.
  • A small amount of condensed water is normal in the EGR valve. If there is too much water, it will certainly burn the EGR valve.
  • 4. Install new EGR valve and EGR cooler for commissioning.
  • When a new EGR valve is installed, the key on / off test can be repeated. Normally, after each key is powered off, the EGR valve will learn by itself once, and an obvious “click” sound can be heard inside the EGR valve.
  • After installation, it is found that the relevant fault code of EGR valve becomes a historical fault code, the relevant fault code of remote accelerator pedal is still a current fault, and the fault lamp is still on!
  • There is a problem with the data because there is no doubt that the car has a remote throttle! Apply for the original factory data brushing. After brushing, it is found that the fault code disappears and the fault is eliminated. After flameout, the “click” sound of EGR valve self-learning can also be heard. Is that fixed?
  • Then go out for test run to judge whether the vehicle is completely repaired. The most important thing is to test run. Only when the test run confirms that there is no problem can it be really repaired!
  • 5. After running about 20 kilometers, I found that the fault light was on again.
  • The car is still weak. Isn’t it repaired? Continue to read the fault code with questions for the next step, and the diagnostic expert reads the fault code.
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After reading the fault code, it is found that the relevant fault code of EGR valve does not appear, but there is a new particle catcher removal fault. Continue to deal with it next

6. The particulate matter trap is the POC on the exhaust and reports the POC removal fault code.

The fault code is monitored by the differential pressure sensor. Within a period of time, the differential pressure before and after POC is basically the same, and the fault code will be activated. Did the POC burn down? Continue to the exhaust pipe with questions.

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The front-end pipeline of the differential pressure sensor falls off, and the front-end pipeline falls off. If the pipeline is the same as the atmosphere, the pressure must be lower than the normal exhaust pressure. POC removal will be reported.


Replace the clamp again and go out for test run again. Look, has it been completely repaired this time?


7. Confirm the fault after running for a period of time.


The final cause is that the internal position sensor of EGR valve is burnt out and the pipeline of differential pressure sensor falls off. Correct the EGR valve, replace the differential pressure sensor hose and clamp, and eliminate the fault.


What chain reactions will be caused by water channeling in EGR valve?


After seeing the fault, many masters raised questions, so the small rail will answer them one by one


1. Where does the water inside the EGR valve come from?


A: water is condensed. For example, put a piece of iron in front and blow with your mouth. Then you can see that there will be water condensing on the iron!


2. Why remove EGR valve cooler for water test?


Answer: most of the water inflow in EGR valve is caused by water leakage in EGR valve cooler. If the driver injects the non-conforming fuel, the sulfur content in the fuel is high.


After the tail gas flows into the cooler, sulfuric acid will be formed when encountering condensate. It will erode the inner surface wall of the cooler. Over time, the cooler will leak!


3. How to deal with the carbon deposit on EGR valve and EGR valve cooler?


Answer: the carbon deposit on EGR valve or cooler can be cleaned with carburetor cleaning agent, generally once every 50000 km.


It can well dispose of the carbon deposit on it. Prevent some power shortage faults caused by stuck EGR valve or water leakage of EGR valve cooler.


4. What is the function of EGR valve cooler?


A: the function of EGR system is to send part of the exhaust gas produced by diesel engine back to the cylinder. Because the recycled exhaust gas is inert and does not participate in chemical reaction, the mixture entering the cylinder is diluted and the oxygen concentration is reduced, so as to reduce the calorific value of combustible mixture.


In addition, due to the large heat capacity of CO2 and steam in the exhaust gas, the specific heat capacity of the mixture is increased and the peak temperature in the cylinder is reduced.


Both of them increase the ignition delay period, slow down the combustion rate and reduce the maximum combustion temperature in the cylinder, thus destroying the conditions of high temperature oxygen enrichment required for NOx generation and reducing the NOx emission of the diesel engine.


5. Why does the falling off of the pipeline at the front end of the differential pressure sensor report the removal of the particle trap?


A: the differential pressure sensor is used to detect the differential pressure at both ends of the post-processing. The sensor sends the differential pressure signal to the ECU. The ECU judges the accumulation degree of particles in the trap according to the differential pressure. When the differential pressure is too large, it indicates that the post processor has been blocked. When the pressure difference is too small, it indicates that the post-treatment can not operate normally.


After the front end falls off, the differential pressure sensor detects that the pressure difference at both ends will deviate to 0, so it will report POC removal fault.

Egr Control Strategy

1. Self learning strategy

In order to eliminate the sensor deviation of valve closing position caused by carbon deposition and other problems, the strategy set in the software is generally implemented when the vehicle closes the key or when the key is started.

2. Current protection strategy

The current limiting strategy is implemented to protect the motor from overheating and burnout of the coil due to long-term operation under excessive voltage.

3. Seating buffer protection strategy

In order to protect the plastic transmission gear train from excessive impact when the valve is closed, the strategy of controlling the closing speed of the valve is implemented.

Egr System Maintenance

Maintenance contents: regularly clean the carbon deposition part of the valve seat.

Recommended maintenance cycle: once / 50000 km or the same as the major maintenance cycle of the engine. The valve body can be cleaned with carburetor cleaner.

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