When the Fourth National Congress came out, most people have been thinking about various operation methods and how to shield urea. Up to now, the most troublesome problem for more people is “not burning urea”. Why is there such a change?
In fact, the advantage of not burning urea is to save urea money, and the disadvantage is to limit torque. Even if it is used for a long time after shielding, the urea system will be greatly damaged and expensive to replace.
Now there are mobile vehicles on the road to catch the exhaust. Check a car in 0.8 seconds and catch a fine, which is enough to buy Urea for one or two years. If you modify the system, the service station will not give you the warranty. Therefore, when the vehicle does not burn urea, we need to deal with it bit by bit.
There is a problem with post-treatment. Urea doesn’t burn = why don’t you burn urea.
To solve the problem of vehicles not burning urea, we often face not one fault code, but a row of fault codes. Aside from non current fault codes, there are also several problems to be solved. Faults and faults are sometimes interrelated, mutual interference or even wrong interference. At this time, it is very important to establish systematic maintenance ideas and methods.
① Most post-processing fault codes need a detection time and meet some code clearing conditions. The code clearing strategy depends on a deep understanding of the working principle of the post-processing system.
② Many vehicle problems are caused by small faults. The more complex the fault, the simpler the cause of the fault. When troubleshooting, we need to carefully check every suspicious fault point, especially the poor connection of the line connector, because the fault often occurs where we don’t think it necessary to check carefully.
③ The form and content of fault code reporting are different, but it may be caused by a fault phenomenon. Therefore, the idea should be clear during inspection, and the problem can be solved quickly and avoid wasting time by troubleshooting one by one according to the principle of easy before difficult.
④ The analysis is very important when the fault code is reported. The problem can be accurately found and solved according to the data flow and in combination with the fault code analysis. The customer’s fault description and understanding of the working principle of post-processing are very important for the comprehensive analysis of the problem.
⑤ Careful investigation and accurate selection are more important than efforts.
The components between the urea pump and the urea tank can be checked if the pressure building fails + the urea is not burned, and the components between the urea pump and the nozzle can be checked if the pressure building succeeds + the urea is not burned. Blockage of pipeline or filter element will indirectly lead to unburned urea of no urea burning.
Filter screen of urea tank: filter when urea tank solution is output to urea pump of no urea burning.
Filter screen of liquid inlet plug of urea pump: secondary filter the solution of urea tank, which is often blocked of no urea burning.
Filter screen of urea pump return connector: filter the return liquid generated during operation to prevent impurities from entering the urea tank.
Filter element of urea pump: the filter paper can filter the impurities in urea solution. The filter element can be replaced after 30000 km or three months.
Air inlet filter screen of air assisted urea pump: filter impurities in the air.
Air assisted air solenoid valve inlet filter screen: filter impurities in the air.
The pipeline is easy to crystallize in cold weather, which is closely related to the heating function of urea heating pipe of no urea burning.
The air of the air assisted urea pump plays many roles in the system. Empty the pipeline and the residual urea solution of the urea pump, and the air carries the urea solution into the exhaust pipe through the nozzle. At the same time, the air cools the nozzle of no urea burning.
The air comes from the vehicle air source, is filtered by the oil-gas separator and enters the pump for pressure regulation. There are two air mixing modes: one is sprayed from the air outlet of the urea pump to the nozzle for mixing, and the other is a mixing chamber inside the urea pump. After mixing in the mixing chamber, urea and air are sprayed from the injection port of the pump to the nozzle for injection of no urea burning.
The heating relay is responsible for heating in the pump and urea pipeline, and a few are responsible for heating urea tank. Failure of heating relay will lead to low urea level temperature, unburned urea and blocked crystallization.
The heating solenoid valve can use the engine cooling water to heat the urea solution externally. One of the preconditions for the operation of the post-treatment system is that the urea has a certain temperature.
Urea heating pipe is usually wrapped by heating resistance wire or electric heating layer for heating. Circuit failure of urea heating pipe will lead to crystallization blockage of corresponding pipeline.
The heating plate in the pump is responsible for heating the internal pipeline of the urea pump. The circuit failure of the heating plate will lead to the crystallization of two heads of the urea pump in three days. Most of the heating resistance of the filter element in the pump is water heating, which is the last heating link before urea injection.
Today, we will tell you a major reason for not burning urea. Later, we will explain other reasons in detail, such as harness and connector / air and liquid leakage / and the fault causes of various components. I hope you will continue to pay attention to our later articles.