Low idle speed on a warm engine: causes and methods for solving the problem. Engine speed does not drop: why does this happen Using ether to start the engine

Hello, dear friends! When operating their car, almost every driver faces certain difficulties and problems. Someone , for others, antifreeze is boiling, and for others, the engine speed does not drop at idle. It is the latter situation that we will talk about today.

This is a widespread malfunction in which the engine constantly keeps revving. Leaving the engine at idle (idle), the tachometer needle still does not want to go down.

Similar situations occur in almost everyone who has an injector and carburetor, diesel and gasoline internal combustion engines under the hood. However, the reasons for injectors and carburetors are different. Let's take a closer look at them.

How to determine if there is a problem

First you need to understand how you can independently determine increased or simply abnormally high speeds in your own car. After all, even at idle there is a certain level of speed and it must be stably maintained.

In practice, identifying a problem that suddenly appears is quite simple. Even in situations where a novice is driving, and he does not have much experience in such matters. The first thing you can do is simply listen to the operation of the internal combustion engine. The lower the engine speed, the quieter it will ultimately operate. But it's even easier to diagnose the problem using , which is installed on the vast majority of passenger cars and trucks. Look at the position of the arrow and record exactly what revolutions you see when driving at a measured, calm pace, and what the device shows after warming up or when releasing the gas.

Depending on the engine, for each power unit There are different idle speed limits. Usually this is from 650 to 950 rotations per minute.

Now take a look at the instruction manual. The normal parameters for XX must be indicated there. If the current values ​​differ from the values ​​​​from the manual, this can be considered a deviation. That is, you need to start searching for the provoking factor.

Owners of injection engines are greatly helped by on-board electronics. If the speed at idle turns out to be higher than the norm set by the manufacturer, at dashboard The check engine light will probably come on. Here I advise you to take a look at our material, where we talked about and their meaning.

Possible consequences

Similar phenomena occur on a large number of machines. Almost any modern and fairly old motor can present its owner with such a surprise. It could be:

• VAZ 2109;
• Renault Logan 1.4;
• VAZ 2107;
• VAZ 2110;
• Chevrolet Sens;
• Mitsubishi Lancer 9;
• Niva Chevrolet;
• VAZ 2114;
• Kia Cherato;
• Chevrolet Lacetti;
• Chevrolet Lanos;
• Toyota Corolla, etc.

It would seem that the speed has increased, but nothing terrible is happening.

In fact, processes can occur in the engine that are initially invisible to the driver. But gradually the consequences will become obvious and often frightening in their cost of recovery.

Under no circumstances should you allow the revs to increase while idling.

This can be explained by several main possible consequences.

Here we are talking about the following potential problems:

• Fuel consumption will constantly increase, which will negatively affect your budget;
• A hot engine leads to problems with the cooling system and a general reduction in service life;
• Often fuel will simply fly away into the pipe, which also threatens its detonation in the exhaust system;
• The total resource of the power unit will begin to decrease;
• The node associated with the increase in speed will suffer.

There are quite a lot of reasons for promptly taking action and eliminating the provoking factor.

Drop in speed on carburetor internal combustion engines

Despite the new environmental standards, in our country the number of cars with carburetor engines is quite impressive.

If you notice that on such an engine the speed is kept at a fairly high level at idle, the reasons may lie in the following:

• The system is not adjusted correctly idle move. If it has been tampered with recently, be sure to check the current setting;
• Problems with . An increase in idle speed may be due to its improper closing. Check the valve for carbon deposits. A chip or crack is also possible. There is only a replacement;
• Needle valve. The reason is its location. It is possible when an incorrect dosage of fuel enters the chamber;
• Head gasket. She simply burned out. Will have to change;
• The choke is open. To check, you need to evaluate the operation of the damper in the primary chamber. If there is a problem, check the operation of the choke. Usually the problem is solved by lubricating the drive and cable.

It is these reasons that most often appear on cars with carburetor engines, when the idle speed remains at an abnormally high level. They are also potentially considered in situations where the engine almost immediately.

There is another option, relevant for carburetor and injection internal combustion engines. Here we are talking about sticking gas pedal.

Problems with the injector

Separately, we should consider situations due to which the speed at idle can increase on injection types of engines.

Unlike carburetor internal combustion engines, where all the problems lie in the mechanical part, the injector has a high probability of having electronic faults.

• Malfunction or failure of the sensor that monitors the coolant temperature. This leads to constant operation in the internal combustion engine warm-up mode. You need a diagnostic scanner and probably a controller replacement;
• Malfunction or breakdown of the XX sensor. It's also a mass air flow sensor. Diagnostics with special equipment will help. Eliminate broken wiring using a multimeter, replace the unit as necessary;
• The same problems, but with the throttle position sensor. That is, the throttle valve. The controller is either jammed or broken;
• Damper return spring. It can stretch or jump off, causing the engine to behave correspondingly at idle. The unit is returned to its place or replaced with a new one;
• Hall throttle cable. Relevant for older cars. Replacing or lubricating will help solve the problem;
• Sealing gaskets on injectors. They don't get damaged that often. Diagnosing the problem is difficult. They usually check it last.

Be careful when launching and observing the behavior of the tachometer in your car. If you see that the speed is floating, rising to abnormal levels and behaving uncharacteristically, do not ignore such symptoms.

Many owners of injection cars could observe the effects when the speed suddenly drops at idle. This phenomenon occurs especially often when the engine is warmed up to operating temperatures. Sometimes the revs drop so low that the engine stalls. Let's figure out what can cause low idle speeds on a warm engine, and also find out why they drop. This information will be useful to everyone.

The origins of unstable engine operation at XX

How will the picture develop if the control unit does not receive data on the quantity and volume of air consumed? So, for example, the reaction of the throttle sensor will be as follows - the speed will initially increase, but then the fuel mixture will begin to become leaner, as a result of which low speeds will be established on a hot engine. There is only one reason for this - the amount of air consumed by the engine has decreased.

However, the opposite happens - the fuel mixture becomes richer, and the engine begins to gain speed again. Such cycles can alternate endlessly; these are floating revolutions. The problem of low idle speed on a warm engine in winter is especially pressing.

On some cars, events may develop differently - the speed increases, for example, to 2000 rpm, and remains there. The reason is that the injector injects increased amounts of fuel. The amount of air does not increase, otherwise the engine would be able to increase the speed to 3 thousand, however, then it would still start to stall.

Fuel quality

When the idle speed drops on a warm engine, you should not discount fuel. It is possible that the problem is not related to the electronics, sensors or actuators. Maybe the whole point is that the driver fills with lower octane gasoline, and the ECU is designed for high-octane brands. Hence the lean mixture, so the control unit has no choice but to work like this.

Possible reasons

So, what causes this problem? Some of the most vulnerable links in injection engines are sensors. One of the elements that directly affects engine performance and quality is the idle speed sensor. You can often find it near the throttle valve. This is a stepper motor with a tapered locking needle. When the throttle is closed, air bypasses the damper through the idle channel, which is blocked by the needle.

Another culprit for very low idle speed is Air - the second important component for cooking fuel mixture after gasoline. Therefore, if the mixture is lean enough, then high speeds will not come from anywhere.

When malfunctions occur in the system, the ECU cannot correctly select and calculate the proportions of the fuel mixture in idle mode. As a result, the engine operation will be unstable, the speed will begin to fall and rise.

A less common problem of low idle speed on a warm engine can be improper operation EGR systems, or rather its valve. The element is installed in the intake manifold and its function is to remove exhaust gases. This is nothing more than Periodically the sensor needs to be cleaned.

It would also be a good idea to make sure that there is no air leak in the system and check the condition of the throttle valve. Often the problem of low speeds can be associated with a dirty valve or its mechanical damage or deformation. It often happens that for one reason or another the valve jams - hence another reason for low speeds.

Why do sensors die?

Experts identify two reasons for low idle speed. One of them is related to low fuel quality. Often, a low octane number not only greatly contaminates the working surface of the sensor, but can also cause various malfunctions in the operation of electronic units.

In addition, sensors often fail due to banal defects or exceeding their service life. Inexpensive sensors may well turn out to be of low quality or defective. This is why low idle speeds appear on cars.

How to prevent air leaks?

In order to exclude or confirm the leakage of excess unaccounted air into the system, check the tightness of the air supply system.

To do this, you can remove the air pipe and blow into it from a compressor or pump. The hose can be placed in water. This will reveal cracks and other defects.

How to check the idle speed sensor?

To check the functionality of the sensor, it is recommended to use a multimeter. The verification procedure is very simple. Replace the resistance between the contacts in the sensor block. It is important that the ignition is turned on. The resistance between different pairs of contacts should be between 39.5 and 81 ohms. If during measurements the multimeter gives different readings, then the sensor should be replaced.

Checking the mass air flow sensor

So, first, to check, turn on the ignition. You need to check the voltage with a multimeter. Measure it between the contacts with the green and yellow wires. On different cars, the voltage can vary from 0.9 to 1.2 V. You can determine if the mass air flow sensor has failed and by appearance spark plugs - black carbon deposits indicate that it is better to replace them.

How to clean the idle air control (IAC)?

When there is a problem with low idle speed on a warm engine, in some cases it can be eliminated by flushing the IAC. To do this, de-energize the car. The regulator is located on the throttle assembly, below the TPS (throttle position sensor). You should prepare a clean rag, a screwdriver, liquid in an aerosol can - this can be any product for cleaning carburetors or injectors.

Cleaning begins with dismantling - to remove it, just unscrew the mounting screws. Sometimes there are also bolts. Once the sensor has been removed from its mounting location, the cleaning process can begin. The work is carried out using rags treated with liquid from a spray can.

It is also necessary to spray the needle from the can. The latter on various car models can be either metal or plastic. The cleaner will not damage the plastic. But the liquid should not get under the spring. If this does happen, it is recommended to blow out the sensor with compressed air as quickly as possible. If this is not done, the liquid will wash out the internal lubricant, which will cause complete failure of the IAC.

Conclusion

As you can see, only a few sensors can provoke low engine speeds at idle. But even one small element can significantly ruin the life of the car owner, especially if the speed does not always drop. But this is not a problem, because this issue can be solved easily, without large investments.

Unstable idle speed or its absence is one of the most common engine problems, which can be solved in a variety of ways.

Engine

One of the most common car engine problems is unstable idle speed or no idle speed. Driving such a car becomes real problem when driving in dense city traffic. In addition to the fact that the driver will be able to learn a lot of “flattering” things about himself from other road users, he can create a real emergency situation.

The idle system is critical to the operation of the engine, from its start to power modes, which is why it is so important to pay attention to it

The idle system is critical to the operation of the engine as a whole, from its start to power modes, and therefore it is so important to pay attention to it. Experienced motorists know what can cause problems with speed on carburetor and injection engines, and most importantly, how to “treat” these unpleasant automobile “diseases”.

Idle system

Early releases had a dependent idle speed, and due to their design they practically did not cause any problems with idle speed to their owners.

However, the times when a liter of gasoline cost 9 kopecks, and a bottle of mineral water - 10, are over, fuel saving has become relevant. It, in fact, contributed to the emergence of autonomous idling, introduced mainly to reduce fuel consumption.

The appearance of autonomous idle in the carburetor design increased the requirements for fuel purity, and also complicated the maintenance of this device. Filters for fuel purification began to be introduced into the power system, since their absence began to directly affect the stable operation of the engine.

If on early carburetors, to set the idle speed it was enough to use a special screw at a certain angle, but now everything has become more complicated. The idle speed was separated into a separate system, with its own channels and jets responsible for the supply and dosing of fuel and air. In addition, an idle speed solenoid valve appeared, which works only when there is power on its winding.

The idle system has become more complicated, which has reduced its reliability, since now any speck or hair in the fuel can lead to interruptions in engine operation or even to its complete stop.

A carburetor equipped with an electric idle valve is more economical in fuel consumption, but less reliable in terms of stability of this same idle speed. This is due to the fact that at any moment the fuel nozzle located in the valve may become clogged, and the power supply to the solenoid valve may also be lost.

Unstable turnover and the reasons for their occurrence

Unstable engine speed can be caused by a sticking throttle valve, mainly due to it not returning to initial position. Most often, the reason lies in faulty damper drive mechanics, or in a large amount of deposits on the inner walls of the lower part of the carburetor.

In this case, it is necessary to check the throttle valve drive elements and clean the throttle assembly. It is better to check the operation of the drive with an assistant: the assistant needs to smoothly press the gas pedal all the way, and the driver needs to follow the throttle drive lever. The damper should take a vertical position and return to its original position without jamming. If the secondary chamber drive is mechanical, then at the end of the stroke of the first chamber damper the secondary chamber damper should also open and then also return to its original position.

When the assistant presses the gas pedal all the way, you need to check the full travel of the throttle valve drive lever, trying to press the lever to its extreme position by hand. If the lever has travel, then it is necessary to achieve its full travel from the gas pedal.

When the valves move unevenly (they close jerkily or do not fully return to their original position), the carburetor must be removed, disassembled and the throttle body cleaned.

If the car is operated primarily within the city, then the secondary chamber damper may generally be jammed, since most traffic in the city is carried out on the first chamber. You should not try to use force to develop it. For these purposes, there is a “Carburetor Cleaning” aerosol that does an excellent job.

Using this product, the throttle assembly on injection engines is also cleaned. In addition, it can be used without disassembling the carburetor: with the air filter removed, it is necessary to inject a small dose of flushing into the primary chamber while adding gas. The engine will seem to “choke”, dropping speed, and will immediately respond with an increase. By repeating this procedure 2-3 times, you can be sure that the throttle assembly is flushed. However, in order to thoroughly “put things in order” in the valve body, it is still better to disassemble the carburetor and wash it in detail.

Floating speed of an injection engine

Unstable idle speed in most cases is associated with contamination of the throttle assembly or foreign air leaks.

If the throttle assembly is dirty (when oil and dirt are visible during visual inspection), its channels become clogged and the idle speed regulator does not completely close the bypass channel. The throttle assembly is removed and cleaned.

If there is an extraneous air leak, the mass air flow sensor gives incorrect data, which either adds or reduces the amount of fuel in order to equalize the mixture ratio. The revolutions, accordingly, either fall or rise. Leakage is detected by carefully inspecting the air supply channel.

“Quick start” - a solution to a problem or an emergency measure?

Unstable engine starting is associated with a malfunction of either the engine itself or its life support systems: fuel and ignition systems (with a working battery and oil appropriate for the season).

Many people use the “Quick Start” engine starting tool, but this is only a temporary solution to the problem. It can be used only in an emergency, when “delay is like death,” but at the first opportunity it is necessary to find and eliminate the cause of the unstable launch.

The “Quick Start” product contains a large number of highly flammable fractions and promotes quick engine starting, which is especially effective at low temperatures.

The Quick Start tool should be used as follows: without starting the engine, inject the compound into the intake manifold or primary chamber of the carburetor, and then start the engine. If necessary, repeat the procedure.

“Quick start” can also be used to diagnose the power system. When unstable speeds and interruptions in engine operation are observed, it is necessary to inject the compound into the intake manifold. If engine operation stabilizes, there is a malfunction in the power system. When no changes are observed, either the ignition or gas distribution system is faulty.

Using ether to start the engine

To start engines, starting fluid – diethyl ether – is also used. The ether has high volatility and a low ignition temperature (when mixed with air in a ratio of 2 to 48%).

However, ether is very insidious; if used ineptly (or using counterfeit ether), catastrophic consequences for the engine are possible literally in the first seconds of startup. This is due to the fact that ether has high speed combustion, creating huge shock loads for all elements of the cylinder-piston group. Its combustion is sometimes accompanied by an explosive effect, which leads to instant failure of engine parts.

To prevent this, additional components are introduced into the starting ethereal liquid that have lubricating, stabilizing, and reducing the combustion rate and the temperature threshold for self-ignition of the mixture.

If this happens in winter, it must be taken into account that the engine must be prepared for winter operation. When starting the engine on summer oil in severe frost, engine parts may simply “stick” to each other and simply break after starting. Besides, summer oil After startup, it will not be able to provide supply to all rubbing pairs, which will greatly increase their wear.

Starting using an ether-containing starting aerosol is best done by two people: one turns on the ignition, and the second makes an injection into the intake manifold (by moving the corrugation from the throttle) by 1-3 presses of the sprayer, and only then the start is made. This will minimize shock loads when the engine starts.

Theoretically, the mixture can be injected into the cavity air filter, but since there have been cases of ignition, it is better to refrain from this method.

A serviceable and fully adjusted engine should start on its own without the use of any starting mixtures at temperatures down to – 35 C. Primary attention should be paid to its technical condition, and starting mixtures should be used only as a last resort.