Categories: News

[百問]Why is the engine not smooth and black smoke? (Part 1)Discussion on the Causes of Turbine Vehicle Failures

The effect of turbo modification is irresistible for many car fans. Even if the original factory is not a turbo car, many car enthusiasts are willing to spend money to install a turbo system for their car to enjoy the thrill of back acceleration, but A turbo car with a more complex power system needs special care to take care of it, and the chance of failure is higher than that of the NA model. Therefore, any car owner who drives a turbo car should have a basic concept of self-diagnosis of the car. True turbo owner.

Question 1: What are the common failures of turbo engines?

First learn from the Turbo system

The sequence of action of the turbocharged engine is that the exhaust gas first flows into the Housing of the exhaust Turbine, and then bypasses the compressor wheel while colliding with the vanes and is discharged from the central outlet, flowing to the Front Pipe to the exhaust pipe in the middle and rear sections. When the drive wheel starts to move, the intake compressor wheel on the opposite side will also rotate, sucking air from the air inlet in the middle into the scroll chamber, and the compressed air will pass through the intercooler to dissipate heat. Finally, it will be escorted into the cylinder to explode. In the process of inhaling air from the filter to the engine, the relevant control part is mainly the flowmeter located behind the filter element, which will inform the ECU of the measured air flow, and order the fuel injector to spray appropriate fuel, and then increase the amount of fuel when accelerating. The pressure solenoid valve will sense the pressure of the manifold, and in the overpressure state, the Actuator will discharge excess exhaust gas to maintain the maximum upper limit of Boost; while the Blow-off valve will be sucked open by the negative pressure when the oil is returned, and the positive pressure air will be led back to the Flow Meter Afterwards, the exhaust gas is directly vented to ensure that the supercharged gas does not reverse back to the turbine. The above is the action flow of the Turbo engine.

Judging from the composition of the entire Turbo system above, there will be poor engine operation, which is nothing more than "intake leakage", "electronic error", and even "turbo damage". The situation reflected by these problems is : "Idle speed instability", "speed limit" and "supercharging abnormality", etc., the occurrence of each situation is not necessarily caused by a single problem, but caused by complex and diverse abnormalities. These faults must be completely avoided. The easiest way to do this is to become familiar with the various failure conditions we have categorized below.

Compared with the naturally aspirated engine, the turbocharged engine has many more peripheral auxiliary parts, and the usage habits are also different from those of the general engine, so it must be taken care of with special care.
To know the positive and negative pressure of the engine at any time, it is indispensable to install a supercharger. It is recommended that you choose a model with a peak memory function, which will be more conducive to observation and the level of supercharging. Of course, if you have a budget If it is enough, it is best to install the exhaust temperature gauge, which can better grasp the combustion status of the engine at high speed.

Question 2: The first cause of unstable idle speed

Checked by vacuum line

Although the current efficiency of new turbo cars has been much more stable than in the past, especially European turbo engines, because of the large number of production, and most of them are strengthened from the original naturally aspirated engine, it is less prone to hardware failures The problem, but I believe that as long as the readers of this magazine, it should be difficult not to upgrade the power of the car, but even if you just write a Stag 1 program, as long as the engine output conditions are different, the chance of abnormality will increase a lot, not to mention The engine is heavily modified, so it is necessary to have a basic understanding of these possible anomalies in order to immediately reduce the strain and continue the problem.

First of all, because of the many vacuum pipes, turbo cars have more chances of idling instability than NA cars, just like when adding a booster gauge, a pressure relief valve, and a booster controller, it will use a connection to the intake manifold. The tee or four-way pipe of the pipe, if the joint of the three-way pipe leaks due to cracks, the vacuum will leak and the negative pressure will become lower, or the engine will suck excess air from here, then the idling instability is inevitable. . In the same way, when there is a slight air leakage in the intake line, the idle speed and negative pressure will also be low, and in the state of full throttle, the situation that the normal pressure cannot be reached and black smoke can be emitted, it is easy to do it. I noticed the abnormality, so why many people will change to the temperature and pressure resistant silicone vacuum tube. It is worth noting here that to understand the condition of the Turbo engine, the prerequisite is to install the Turbo meter, otherwise it will be difficult to check. This meter is a necessary preliminary diagnostic tool for turbo car owners.

In order to prevent air leakage, the Turbo engine should use Silicon vacuum tubes and intake joint tubes, and it is also necessary to use better beams.

Question 3: The second reason for the unstable idle speed

Dirty air core or flow meter

Regardless of whether the Turbo car or the NA car, once the air filter is too dirty and blocked, the idle speed will definitely decrease due to the increase of the suction resistance. Although the idle speed motor will automatically increase the speed at this moment, due to One active and one passive cut into each other. Some of the more sensitive idle speed control systems will cause the phenomenon of shortness of idle speed. In addition, the air filter is too dirty, and the performance of high-speed horsepower is not good, so regular cleaning is very important. important.

In addition, many original turbo cars will be equipped with an air flow meter. Since it is connected to the rear of the filter element, it is difficult to avoid contamination. If the Flow Meter is too dirty, it will send a wrong message to the ECU. , and then affect the correct amount of fuel, such that the idling speed is unstable or even the engine is weak. However, it is best not to clean the flowmeter casually, because the hot wire core in it is very fragile, and it will be completely broken if it is not fixed.

Question 4: The third category of idling instability

Caused by modified pressure relief valve

In order to increase the competitive atmosphere of the car, almost every turbo car owner will definitely change the intake pressure relief valve to an external leakage type, but some original supercharged vehicles will experience low idle speed and oil return when the external pressure relief valve is changed. In the case of flameout, this is because the valve of some intake pressure relief valves is relatively large, and too much air is released when the oil is returned to relieve pressure, causing the flowmeter or manifold pressure gauge to transmit the intake air volume signal to the computer, which is related to the actual engine intake flow. If the difference is too large, the result is that the oil and gas is too concentrated, which leads to a low speed or even a flameout. There are two solutions: one is to change the position of the flowmeter to the position of the intake pressure relief valve, so that the air flow detected by the flowmeter can match the actual flow into the engine. It is possible to change the way of detecting the intake air volume to the manifold pressure type, but this requires the assistance of a modified computer, which is considered a practice for heavily modified players.

In addition, the valves of some original pressure relief valves are relatively soft. When the engine is fully supercharged, pressure leakage will occur, and the originally set pressure value target cannot be achieved. The solution is to replace the modified intake pressure relief valve. This problem can be solved by a relatively hard spring or by adjusting the load of the spring. Of course, this is also a problem that needs to be faced under the high pressure setting. Therefore, the leakage type pressure relief valve should not be bought and changed. It is also necessary to confirm whether the vehicle can be used, whether the computer program needs to be corrected after the replacement, whether the hardware pipeline needs to be adjusted, etc.

The disadvantage of modifying the external release pressure relief valve is that it is easy to affect the oil supply ratio of the computer due to too much released air, and the acceleration force of the oil return will be worse than that of the circulating type.

Question 5: The fourth category of idling instability

Booster Motor/Injector Inspection

If you have thoroughly cleaned the air core and flow meter, and the entire intake pipe is not cracked, but the idle speed is still unstable, then the speed-up motor or electronic throttle valve on the engine may have serious carbon deposits and need to be disassembled completely. Cleaned up, especially if your car's in-cylinder direct injection fuel supply system uses single injection instead of internal and external dual injection, a lot of sludge will often accumulate in the air intake and throttle valve. These sludges are used for engine intake and exhaust cooling. In addition to affecting the idle speed stability, the accumulated problems will also reduce the peak power output at full throttle. Therefore, it is necessary to regularly remove the intake manifold for sludge cleaning.

If you have even cleaned the sludge, but still can't find the problem of unstable idle speed, it is recommended to use a screwdriver to touch the fuel injectors of each cylinder to see if there is any action, because one injector If the fuel nozzle does not inject fuel, the idle speed will not be stable. To solve the problem of no fuel injection, you can first check whether the plug is detached or loose, fix it and then confirm. If it still does not work, you need to go to the factory to confirm the fuel injection of each cylinder. Whether the amount is consistent, sometimes the needle valve in the injector is worn or the coil is faulty, etc., which will cause the injector to operate abnormally, regardless of whether it is a direct injection engine in the cylinder or not.

If the fuel injection nozzle blocks the nozzle holes due to carbon deposits or gasoline impurities, resulting in uneven fuel supply per cylinder, idle jitter will also occur. In severe cases, the engine will have severe knocking or even internal injuries. It is also helpful to save fuel consumption by removing the fuel injector for cleaning.


Dreamer is what I am, but unlike many, I struggle to make my dreams come true. I own, seo, admin and site editor. I am a father, married, Christian, Northeastern/Brazil and Libran. I love cars <3

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