Vibration at idle: causes and remedies

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Idling is the operation of the internal combustion engine with the clutch disengaged and the transmission in neutral. In this scenario, there is no transfer of engine torque to the cardan shaft, that is, the engine is idling (hence the name). In this period of operation, a serviceable engine should not show any characteristic signs in the form of vibrations, pops and extraneous sounds. But if there is vibration at idle, it means that there have been changes in the engine that can significantly affect its operation from the wrong side. In order not to reach an expensive repair, you should not hesitate to eliminate this malfunction. And why there is a strong vibration at idle and how to fix this problem, our today's article will tell.

What is the normal number of revolutions?

Depending on the type of engine, during normal idling, the number of revolutions of the crankshaft is from 800 to 1000 per minute. If the value is below this mark, the motor simply stalls. Well, in the case of increased idle speed, the engine will absorb more fuel. At the same time, all parts and components of the internal combustion engine endure heavy loads, and, accordingly, their service life decreases.

Reasons

Why does vibration occur at idle? Most often this happens due to the following reasons:

• Tripling of the engine. In this case, one of the engine cylinders may not work.
• Incorrectly fixed engine.
• Other factors. We will talk about them a little later.

Tripling

So, the first reason that provokes the vibration of the motor. Engine tripping is the most likely cause of the unstable operation of the internal combustion engine, since when the cylinder is not working, there is a significant imbalance and improper distribution of the load on the crankshaft. As a result, you can observe how the motor twitches from side to side. Also, when tripping, the vibration of the steering wheel is noticeably felt. At idle, all these signs are noticeable to a greater extent. The more the shaft rotates, the less strange vibration will be felt. But at the same time, you will notice how the car began to absorb more fuel and noticeably lose power, especially when driving "downhill".

There is only one solution in this situation - to urgently repair the non-working cylinder. If this is not done on time, coking of the KShM parts will soon occur. At the same time, their service life will noticeably decrease, since the fuel does not burn out in the chamber, but only washes away the grease.

Wrongfixed engine

This is also one of the common reasons why there is a vibration on the body at idle. Most often, this problem is associated with the wear of one of the pillows on which the engine is mounted.

Also, vibration on the body at idle occurs due to the use of too rigid fasteners. But wherever this problem is hidden, it definitely needs to be addressed. Of course, an improperly fixed engine is not as bad as a broken cylinder in it. But still, in order to avoid constant shaking and sounds, you should change the supports, or adjust their position in the right direction.

How to find out the shortcomings in the engine mount? It is very easy to do this. To do this, you need to open the hood and call an assistant to alternately turn on the “neutral”, reverse and forward gears. At this time, you should pay attention to the position of the engine on the supports. Thus, you alternately unload the pillows that hold the motor. With each new gear change, the engine will deviate in different directions at the same angles. If it deviated more than usual to one of the sides, then the pillow needs to be replaced in this place.

Other factors

Besides a broken cylinder and an improperly fixed engine, vibration at idle can be caused by a number of other factors. Of course, they are much rarer, but still they should be considered as an option.

BFirst of all, it is necessary to note the elements of the fuel system. If they are heavily contaminated, the air/fuel mixture will not burn properly. Because of this, there is increased consumption, strange sounds (perhaps even pops) and vibration. It's even worse if water gets into the gasoline. In this case, in addition to a large waste of fuel, there is a risk of coking of the cylinders. As a result, the engine does not work properly. Sometimes engine oil and soot can enter the fuel system, which also negatively affects the engine cycle.

The second reason is the different weight of the parts of the cylinder-piston group. The operation of a car, especially if its mileage is more than 200 thousand kilometers, requires increased attention to the engine, and sometimes the replacement of parts in it. Even a small difference in weight can significantly affect the performance of the engine in the future. And this applies to all engine parts, be it a piston, connecting rod or skirt.

On some small cars with an electronic damper control system, cabin vibration at idle may occur due to increased load on the generator. This happens especially often in the winter, when headlights, a stove, heated windows, seats and mirrors work simultaneously in the car. Often on such cars, vibration occurs at the moment of stopping. When the driver releases the accelerator pedal, the on-board computer sends a signal to close the damper to idle, and the engine receives a load from the generator - it is at this moment that a strong shaking of the engine occurs. It usually disappears after3-5 seconds. This vibration at idle for small cars, especially with automatic transmission, is considered normal, and in most cases it is solved by using better fuel and replacing the air filter.

It is worth noting that motor shaking can also occur when replacing a toothed belt, especially when the balance shaft gear rotates with the removed part.

After the displacement, it is unlikely to fall into its original place. Therefore, when replacing the belt, do not rotate the shaft gear with your fingers, unless you want to assess the condition of the bearings. But even here you need to be very careful and careful. Any misalignment of a part can result in vibration that creates permanent discomfort for you and your passengers.

Crankshaft balancing

It also happens that vibration at idle appears after replacing the crankshaft. The fact is that this element, like a regular wheel, must undergo a calibration procedure before installation. It is balanced on a special stand with a flywheel and a clutch basket. At the same time, the master drills out excess from its surface. If this procedure was not performed, and the crankshaft was installed without prior calibration, expect strong shaking.

What are the consequences of low idle?

Driving and running the engine at excessively low RPMs, especially when attempting to accelerate, can cause rapid wear of the following items:

• Motor pistons (this destroys the blockcylinders).
• Crankshaft bearings.
• Clutch baskets.
• Flywheel.
• Transmission bearings.
• Timing chains. At low shaft speeds, it simply stretches.
• Cylinder liners. Due to soot, their walls are damaged.

Thus, with constant vibrations, rapid wear of engine parts occurs. At the same time, its promotion is carried out much more slowly, and the crankshaft packing is greatly destroyed. As a result, there is a risk of oil leakage.

Intentional under-revving

Some motorists deliberately make the idle speed below the norm. This is often done to save fuel. However, as practice has shown, this solution is not very correct. It should be remembered that the repair and replacement of worn engine parts can be more expensive, and dozens of times. Therefore, do not intentionally underestimate the engine speed, thinking that this will save your wallet.

How to adjust the engine?

So, we have a vibration at idle. What can be adjusted here? To do this, you need to pay attention to several components and assemblies included in the fuel system. Depending on the type of car power supply, this can be a carburetor, an injector, as well as a host of various electronic and mechanical sensors, the number of which on modern cars already changes by dozens. In addition to these elements, the fuel pump is also regulated.

When making adjustments, remember thatthe number of revolutions directly depends on the degree of compression of the throttle valve, which regulates the air supply to the cylinder, as well as on the operation of the idle valve, which supplies oxygen independently of the first part. This value is increased using the accelerator pedal. So you can equalize idle speed to values \u200b\u200bof 800-1000 rpm.

How to save the resource of engine parts in different operating modes?

In order to extend the life of the motor, you need not only to monitor the normal number of rotations of the crankshaft. He will also be able to properly operate the car, choosing the optimal range of work. Experts recommend upshifting in the rpm range between peak torque and maximum power. At the same time, while driving under a high load (for example, when driving on a hill), it is not necessary to allow the shaft torque to fall to values close to idling.

As soon as you feel the characteristic vibration of an overloaded engine, immediately shift to a lower gear. Otherwise, the motor parts will be subjected to high loads. This can cause failure of the entire cylinder-piston group. Remember that high revs for an engine (especially a gasoline one) are not as bad as low revs. If you have a gasoline car, change your driving style so that the engine speed does not drop to 2 thousand or less when driving. In this case, it is allowed to spin the crankshaft up to values6000-8000 rpm As soon as you feel that your car has stopped pulling and is about to run out, switch to a lower gear and in no case allow the speed to drop to the point of vibrations, especially if you are going downhill. Operating the car in this mode will save parts from premature wear. At the same time, this "high-speed" driving style is in no way reflected in increased fuel consumption.

Conclusion

So, we found out why vibration occurs at idle, how it can be caused and how to eliminate it. Thus, the fight against engine shaking plays a decisive role in ensuring the safe, reliable and durable operation of the car for hundreds of thousands of kilometers. Any vibration, including idling, is very harmful to the car. It not only brings discomfort to you and your passengers, but also significantly harms the engine. The situation can reach up to unauthorized unscrewing of bolts and nuts. Already these malfunctions can lead to the most unpredictable consequences.