Last Friday, an Audi A4L came to the factory for inspection and repair. The owner is a friend of a master. The problem with the car is: the engine shakes, the acceleration is weak, and the instrument is still lit with a fault light.
This Audi A4L was delivered in 2012. It is equipped with an EA888 engine and has a driving range of nearly 150,000 kilometers. Its engine has not undergone major repairs, so the master initially guessed that the problem may be related to carbon deposits, or it may be Problems with fuel injectors or high-pressure fuel pumps are common problems with this engine.
After knowing the basic situation of this Audi, the master connects to the computer to check, the fault code is shown in the figure below. Based on these faults, the master can basically determine that there is a problem with the 1 cylinder injector. This is very similar to the previously repaired Volkswagen CC failure, but the CC problem is more serious.
The disassembly of the fuel injector is slightly more difficult, because it is located at the lower part of the intake manifold, which requires careful disassembly, especially some plastic air pipes and water pipes. As shown in the picture below, the two masters are disassembling.
During the disassembly process, the master found a problem with the flap control plug harness of the intake manifold. As shown by the arrow in the figure below, the rubber on the outside of the harness has been damaged, which must be wrapped with tape.
About half an hour, the two masters removed the intake manifold, as shown in the figure below, the number indicates the number of cylinders.
As shown in the figure below, this is the intake manifold assembly. The arrow shows the 1-cylinder injector. The master decided to disassemble the 1-cylinder injector for inspection.
How to check the injector? The master used high-pressure air to blow the nozzle of cylinder 1 and then checked the nozzle outlet indicated by the green arrow. It was found that there was always gas blowing out of the outlet, indicating that there was a problem with the internal seal of the nozzle, and it was in a long-pass state. The nozzle was normal. It should be unreasonable. This will cause problems with more than one cylinder fuel injection and the engine will shake.
This is different from the CC that was repaired last time. The CC has 3 injectors that have problems, but it is only a problem with the 1 cylinder injector. This time the master suggested that the owner only replace this one.The owner also agreed.
Considering that the intake manifold of this engine is being disassembled for the first time, the master inspected the intake valve specially. As expected, there is a lot of carbon deposit on the intake valve, as shown by the arrow in the figure below. These dark ones are carbon deposits and very hard.
The above picture shows the carbon deposits on the intake valve of 1 cylinder, and the other 3 cylinders have a lot of carbon deposits on the intake valves, as shown by the arrows in the figure below. After seeing this situation, the car owner was very surprised, why so much carbon? At this time, the car owner is very worried about the engine, will this damage the engine?
The master told the owner that there are so many carbon deposits on the intake valve, which will definitely affect the engine. If it is not maintained for a long time, the engine is likely to have major problems.
This engine still has the problem of burning oil. It can be seen that the 2-cylinder intake valve rod will leak oil. These problems can be regarded as its common problems. Fortunately, its four cylinders are normal. Generally for this situation The maintenance is: clean up the carbon deposit on the intake valve, replace the valve oil seal and improved timing set, and soften the piston ring without disassembly. In this way, maintenance costs are relatively high.
However, the owner of the car has limited funds at this time and does not want to spend so much money on repairs. He just wants to solve the urgent problem now. In addition, the owner is a friend of the master, which is equivalent to his own car, so the master decided to replace it with a fuel injection And clean up the carbon deposits on the intake valve. As shown in the figure below, this is a tool used to clean up carbon deposits.
First, the master uses a steel wire to remove the large carbon deposits on the intake door, as shown by the arrow in the figure below. This is the cleaned carbon deposit, which is similar to clay. For cleaning up the carbon deposits in the intake valve, the master generally says that it is "coal mining".
As shown by the arrow in the figure below, this is the intake valve after cleaning up the large carbon deposits. These two valves are closed, so there is no tool scratching the valve stem, and there is no carbon deposit. Will enter the cylinder. This effect looks okay, and it will shine after cleaning with detergent and blowing it clean.
The other intake valves are also cleaned like this,The results looked good, but after a thorough inspection of the engine, the master found that its high-pressure oil pump leaked oil and the water pipe joint leaked coolant. The picture below shows the high-pressure oil pump leaking gasoline, from the upper part of the arrow position leakage.
Therefore, the master also recommends that the owner replace the high-pressure oil pump and the water pipe joints. If the high-pressure oil pump is not replaced, the leaking gasoline from the high-pressure oil pump will enter the engine and affect the lubrication; if the leaking coolant joint is not replaced, the leakage rate will increase. The faster it affects the heat dissipation of the engine.
After the car owner knows, he directly agrees to replace it. After all, a friend said. Finally, the master changed a fuel injector, a high-pressure fuel pump and a water pipe joint, and cleaned the carbon deposits on the intake valve. After all the installations, the engine started normally.
Although the repair is not perfect, the urgent problem has been solved, and the car owner can drive with peace of mind during the Chinese New Year. The riders have a brief understanding of the maintenance process of this Audi, hoping to help riders.
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