The car stalls when you let off the gas: causes and solutions

Surely every car owner has experienced such an unpleasant situation when the car stalls when releasing the gas.
This problem is one of several most common. To begin with, I would like to clarify why the engine may be plugged during a reset. The very first and most common problem is the banal clogging of the gap in the throttle valve. Another equally popular problem is the dying of the regulator, and they can break quite often.

It’s not uncommon to hear from people that it got to the point where they had to completely change it. Or some people benefit from a very serious and deep flush.

Candles

Let's start with the basics - candles. If the engine stalls when you release the gas and loses dynamics, the first reason is the spark plugs. Checking them is quite simple: unscrew them and look at the contacts. If they are sooted, then most likely there is no spark and, as a result, the cylinder is switched off from engine operation. If possible, it is better to change the kit; if not, clean the contacts and go to the nearest auto shop. When cleaning, you should try not to change the distance between the contacts. This operation is performed with simple sandpaper; if you don’t have it, then a pocket knife will do.

When releasing the gas, the speed is increased or “freezes”: common malfunctions

Let's start with the fact that on many cars with an injector, the ECU raises the speed while the internal combustion engine is warming up. This is necessary to ensure that the power unit operates stably after a cold start.

However, after the temperature rises, the control unit reduces the idle speed, bringing it to normal. On many cars with a carburetor, the driver independently increases the speed during warm-up, using the so-called “choke”.

Moreover, after the engine is warmed up, the normal idle speed is, on average, 650-950 rpm. If you press the gas and release the accelerator, the speed should increase, and then decrease again to the specified values.

• So, let's start with common carburetor problems. Often the engine speed does not drop due to problems with the throttle valve. For example, when the driver steps on the gas, the throttle must be opened wider to allow more air to enter the cylinders to burn fuel. After the gas pedal is released, the throttle closes and the speed decreases.

Checking the idle speed sensor (IAC)

Finding the sensor is not difficult; it is located under the throttle assembly and is secured with two bolts. If the throttle assembly (DU) has not been cleaned for a long time, then the conical needle of the sensor and its seat could become clogged and produce incorrect data. The main reason indicating a sensor malfunction is that the car stalls when releasing the gas and changing gears. The problem is solved by removing the throttle assembly and washing it with carburetor cleaner. It is difficult to remove the sensor itself without a remote control. All you need is a small screwdriver and a lot of flexibility. There is also a high chance of missing a screw or two. Usually no one has a replacement for them.

Sensors

The first of them is the idle speed sensor.
This device is located in the engine control system. It is used in cars to stabilize idle speed. Its abrupt performance often precedes the engine turning off when the gas pedal is released. If this is exactly the sequence, then with a 90% probability this particular sensor is involved and you need to start digging in its direction. As you can understand, this sensor is designed to supply air to the engine to maintain normal idle speed. This sensor is a very important component of the entire fuel supply system to the engine, and it works closely with the injection system.

Second

– this is an air flow sensor, it is located in the same system as the previous one, only it works more globally and is responsible for a greater number of operations.
If this is not the problem, then you can look towards low-quality gasoline (this happens, and not rarely). So, you should pay great attention to the selection of gasoline. Additional article “Which cars require 98 gasoline.”

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Injectors

Fuel is injected into the cylinders through electromagnetic injectors. Due to poor quality fuel, they can become clogged and not allow enough fuel into the cylinder. Hence we have the fact that the car stalls when the gas is released. The injectors are installed on the fuel rail. Everything can be easily removed, and you can carry out the injector cleaning procedure yourself in your garage. You just need to first buy new rubber gaskets for the injectors and carburetor flushing fluid. We put the wires from the battery on the nozzle and supply liquid from a can of cleaner into it under pressure through a standard tube. It is necessary to achieve good atomization of the liquid coming out through the nozzle; when voltage is applied from the battery, the nozzle should click. If this does not happen, then it must be replaced. But it’s better to contact a service center that has the necessary equipment and will do the washing procedure much better.

"Women's" reasons

This conditional category includes reasons that sometimes arise for people who are inattentive or do not service their car in a timely manner.

These include:

1. Buying fuel at “left-handed” gas stations – this category also includes the purchase of cheap “grades” with various additives disguised under the names “E”, “ER” and others. It is not profitable for large chain gas stations to deceive customers, because selling normal fuel is cheaper than giving bribes to everyone, especially when it comes to the scale of the country, but the legislator does not prohibit selling some 95Er, with the alcohol content honestly indicated in the specifications. All drivers know about this, but greed takes over and such fuel kills the engine over time. The same situation has developed around “cheap underground” gas stations selling fuel siphoned off from truckers or military personnel.
2. Dirty fuel and air filters - a symptom of this problem is when the VAZ 2114 stalls while driving or when you press the fuel pedal. Both filters are involved in the process of forming the fuel mixture, therefore, when the fuel one breaks, the gasoline supply is unstable, and if the air filter is used, the mixture becomes over-enriched, which in both cases leads to flooding of the spark plugs.
3. Spark plugs - this car part can fail not only due to the reasons described above, but also due to age and improper care. Experienced car enthusiasts check spark plugs in VAZ cars at least once a month. To do this, you need to unscrew it with a spark plug wrench and evaluate the carbon deposits - the working spark plug has a light gray electrode and a light brownish carbon deposit. If the color is different, it's time to purchase a new set.
4. Lack of fuel - everyone knows that it is better to drive on a full tank, but domestic motorists, due to the constant lack of money, the eternal crisis in the country and other similar reasons, prefer to drive on an almost empty tank and refuel only when absolutely necessary. At the same time, the accuracy of FLS on domestic cars is far from ideal and VAZ is no exception. Therefore, stopping at an angle, driving until the car stalls, topping up the tank on the road from a canister have a very negative effect on the fuel system, debris gets into it, and fuel is constantly supplied along with air.
5. “Left” service stations - the saying “the miser pays twice” is most relevant when it comes to cars. Garage services, repairs from friends and other attempts to save money often turn into the fact that your VAZ 2114 injector does not idle, there are engine problems, and repairs need to be carried out at an official service center.

Tachometer with high speed

Fuel pressure regulator (FPR)

The RTD is quite easy to find; it is installed on the fuel rail and has the shape of a cylinder. It is a regular valve that reacts to excess pressure and supplies more fuel to the engine. Again, due to low-quality fuel, it can become clogged and jam. This malfunction is not critical, but because of it, when you release the gas, the car stalls, the engine is difficult to start, dynamics are lost, and the idle speed “floats.” RTDs are inexpensive in stores and available almost everywhere. Changes in a few minutes.

Air filter

Replacing filters in a car is an important maintenance procedure that many people forget about. As a result, the filter becomes clogged and the operation of the power unit and systems is disrupted. If there is severe contamination or damage, the engine will run unevenly and jerkily—it will stall when you press or release the gas pedal.

Attention! The engine stalls in the same way if the XX regulator fails.

To verify the malfunction, you need to dismantle the filter and inspect for damage. If dirty or worn, replacement is necessary.

Clogged air filter

Mass air flow sensor (MAF)

The most expensive sensor, therefore, it is changed as a last resort when all else fails. It is located on the pipe, after the air filter. It's easy to check: remove the connector from it and start moving. If the engine does not stall when you release the gas, then the reason is in the sensor. It's difficult and tedious to understand. It can be treated by specialists with equipment, but it will cost about the same as the sensor itself. Therefore, it is better to buy a new one. The main thing when purchasing is to indicate the number and manufacturer that is indicated on your sensor. Your ECU firmware may not work correctly with other sensors. Installed with simple clamps. We also recommend changing the air filter along with it. It costs a penny, but it will protect you from failure of the new mass air flow sensor.

GAS FAILURE AT THE DISCHARGE

When you let off the gas, either approaching an intersection, or simply accelerating in place, in neutral, the tachometer needle should drop to idle speed (idle). At the same time, it (this is how it is intended; why is a separate topic) under no circumstances should it fall below XX. For example, if the engine is adjusted to a speed of XX 800 rpm, then the needle should not fall below these 800 rpm when the gas is released. Naturally, provided that all loads are turned off. And, of course, all engine systems are in good working order. This part will describe the reasons known to us for gas failure at the discharge. By the way, this failure is sometimes so strong that the engine even stalls. So, with a working engine, when you release the gas, the tachometer needle should smoothly return to XX speed and remain there. Until it occurs to you to press the gas pedal again. If the gearbox is in the “neutral” (or “parking”) position, then it will be 650 - 800 rpm. If any gear is engaged (“D”, “R”, etc.), it will be slightly less (it is considered normal to reduce the speed to 150 rpm, but this depends on the ECU software of each specific model). It should be noted here that the idle speeds recommended by the manufacturer (those indicated on the engine compartment plate) are not a dogma and can be slightly changed by adjustment. This adjustment should be based on the following considerations. The higher the idle speed, the greater the fuel consumption, the hotter the engine will be, the more dirt will fly out through the exhaust pipe (nature will suffer), the greater the load on the automatic transmission will be (the gears will engage with a shock if there is at least a little wear there in rubber seals), etc. In short, everyone will feel bad. Except for the engine. At 1000 rpm it will be just fine! The oil pressure will be high. This means that there will be less wear and tear on all its glands that are lubricated with this oil. On the other hand, the lower the idle speed, the worse the life of the engine will be. But everyone else will be fine. For these reasons, craftsmen set the speed to XX when adjusting the engine. Old, worn-out engine - give it more revs XX. A good engine is smaller. Naturally, within reason. But in any case, when releasing the gas, as already mentioned, the tachometer needle should not fall below the set XX speed. In general, the reason for the failure of gas at engine speed reduction in all types of engines is caused by the mismatch of the composition of the fuel mixture with the technical requirements at the moment. This may be an excessively lean mixture (more common in diesel engines) or an excessively rich fuel mixture (more common in gasoline engines). This is due to the fact that when the gas is released, the engine operating modes change very quickly and the engine control systems do not have time to react correctly to this. Provided they are in good working order. Diesel engines. If a diesel engine experiences a loss of gas at the outlet, then, as a rule, the fuel injection pump is faulty. And the “treatment” of this injection pump will most likely involve replacing parts. Right down to the body. This is if you do it according to import instructions, but there may be options, more on that below. Before passing such a harsh sentence (injection pump faulty), we recommend doing the following. Sometimes it helps. Check whether there is a TPS (TPS - throttle positioner sensor) and if so, whether the idle speed is turned on. In other words, does the engine control unit (ECU) “know” that the gas pedal has already been released and the engine is idling? Older (not by production, but by year of development) diesel engines do not have a throttle valve. There, information about the degree of pressure on the gas pedal is provided by the fuel control lever position sensor. This sensor is located on the top of the fuel injection pump (less often in the cabin, on the floor near the gas pedal), looks exactly the same as the TPS and performs the same function - it gives the ECU information about the degree to which the gas pedal is pressed. Based on the signals of this sensor, not only the engine is controlled and its various systems are turned on, but on many models, for example, in almost all cars, the automatic transmission is switched. (FIG. 32, FIGURE 33) Fig. 32 Fig. 33

Rice. 32. Throttle valve block. 1– a rubber plug, under which in the recess there is an idle speed adjustment screw for a flat screwdriver; by unscrewing the screw, you can increase the idle speed, by tightening it, you can decrease it; many modern engines do not have this adjustment; 2 – throttle damper, this element is also absent on the most modern engines; 3 – the idle speed stabilization electric motor raises (stabilizes) the idle speed when the engine warms up, when the side lights, air conditioning, heated rear window, etc. are turned on, it also plays the role of a controlled damper. Often this motor gets jammed due to dirt and it does not work. To repair, you need to remove the housing and, using aerosol cleaners, remove the rotor of this motor. 4 – screws securing the idle speed stabilization motor housing; by loosening them and turning the motor housing, you can change the idle speed. This is exactly how idle speed is adjusted on a significant part of modern gasoline engines. 5 – “tracks” of the throttle position sensor, wear of these “tracks” leads to voltage surges in the signal wire and the ECU turns on the “check” light with the TPS fault code, as well as a bypass program.

Rice. 33. Not only engine operation, but also the shifting moments of the automatic transmission depend on the adjustment of the fuel lever position sensor (all mechanics habitually also call it TPS). Adjustment is carried out by loosening the TPS mounting screws and turning the sensor body to the selected angle. Craftsmen often set TPS according to the resistance specified in the technical requirements. But they can make fine adjustments by eye, literally turning the TPS body by fractions of a degree.

Next you need to check whether there is a vacuum damper on the fuel lever or on the throttle valve, and whether it works. Most Japanese diesel engines do not have this damper; everything is done for it by an all-mode regulator inside the fuel injection pump, but you should still check, maybe your engine is an exception. Check the correct operation of various environmental devices. Maybe turn them off altogether. To paraphrase one famous leader: there is a system - there may be a problem, there is no system... We are talking about the EGR system, the system for forced shut-off of intake air, etc. If all the checks have been carried out and everything seems to be in order, but the engine still tries to stall when you let off the gas, you can try this. Rough adjustment of the fuel supply volume will increase the injection volume. On a mechanically controlled injection pump, to do this, tighten the adjusting screw so that the idle speed increases by approximately 200 rpm. Then, if everything goes well, they can be lowered with a special adjusting screw for adjusting the XX. On an electronically controlled injection pump (Nissan, Mitsubishi, Isuzu), to increase the flow volume, you need to loosen the screws securing the spacer (they are usually flat slotted, hexagon screws secure the cover) and move it a little back. Literally fractions of a millimeter. After this, you should check whether the gas gap remains and, perhaps, reduce the idle speed. To do this, try changing the TPS adjustment. Often such actions help. But they do not eliminate the cause, wear of fuel injection pump parts. This is like “healing” the pump for a while. Gasoline carburetor engines. Gas failure at the discharge is usually caused by improper operation of the damper, malfunction of the lean system, or EGR system. There may, of course, be other reasons, but they, as a rule, also cause other defects. For example, if the compression is too low, the carburetor is incorrectly adjusted, the ignition system is faulty, etc., the engine will also tend to stall when the gas is released. But there will also be other negative phenomena. The damper prevents the throttle valve from closing abruptly.(FIG.34,FIG.35)

rice. 34 pics 35

Rice. 34. Uncontrolled throttle damper. In the body of this damper, on the side shown (1), there is a small hole for air to escape. The adjusting screw (2) provides clearance (A) of the throttle valve (3). If the gap (A) is removed, the throttle valve will jam in the closed position, which is very unpleasant for the driver.

Rice. 35 Stages of operation of the throttle damper. A – full or medium throttle. The throttle lever does not reach the damper rod, and this allows the throttle valve to move in any direction very sharply. The damper rod is fully extended. B – gas pedal is released. The throttle lever rested against the extended damper rod and the rod began to slowly press in. The damper rod touches at 1100 - 1300 rpm, and this value is adjusted, as shown in step B. B - adjustment of the damper response value.

When the gas is released somewhere in the range of 1200 - 1500 rpm, the damper rod rests against the throttle lever and then the damper is forced to close smoothly. There are uncontrolled and controlled dampers. The amount of damping depends on the following. First, the damping rate depends on the area of ​​the diaphragm, the magnitude of the spring force, and the size of the “hole” through which air is displaced. Secondly, vacuum is also supplied to the diaphragm through a rubber tube, and they are triggered by a signal from the ECU. Controlled dampers can also be used to increase idle speed. This is sometimes required when turning on the headlights, air conditioning, etc. The lean system is designed to allow additional air (or an additional amount of a very lean fuel mixture) to enter the intake manifold when the gas is released. This is necessary in order to prevent enrichment of the fuel mixture during gas discharge. After all, when the gas pedal is released and the engine is still spinning at high speeds, a very large vacuum occurs in the intake manifold. This vacuum breaks off all the drops of gasoline that have condensed on the inner walls of the intake manifold, and literally sucks all the gasoline out of the carburetor. The fuel mixture naturally becomes richer and the engine, “dissatisfied” with this, drops the speed below idle. Fuel consumption in this situation is naturally increased. The lean system can be implemented in the form of a separate solenoid valve on the intake manifold, which (according to ECU commands) opens every time the speed increases above 1500 rpm, and closes when the gas is released below about 1200 rpm. At idle, no additional air is supplied to the intake manifold. This method, supplying additional air at the gas outlet, is most often used in its cars. in its cars it uses slightly different methods to lean the fuel mixture. Firstly, this is a special device on the carburetor (BCDD - boost controlled deceleration device - a device for controlling pressure in the intake manifold in deceleration mode, located on the carburetor on the side of the secondary chamber), which is activated every time the vacuum in the intake manifold rises above the vacuum at XX. Secondly, a controlled power valve, which controls not only the additional fuel in full power modes, but also the air for braking the fuel of the main metering system. This valve, located in the float chamber, is controlled by the ECU. Other manufacturers use combinations of the above techniques. The EGR system (EGR - exhaust gas recirculation - exhaust gas return) is usually turned on at the gas discharge. But when it reaches about 1500 rpm it should turn off. If it does not do this in time (due to dirt in the control valve or because the TPS is set incorrectly and the ECU unit receives incorrect information), then a failure of gas will be observed at the reset. In gasoline engines with fuel injection, the cause of gas failure may be improper operation of the damper, improper operation of the XX motor, and an incorrect fuel mixture. With the damper everything is the same as with carburetor engines. The throttle valve, especially at the end of its stroke, should always close smoothly. For this smoothness, a damper is installed. (FIG.36)

Fig.36

Rice. 36. Design of some types of uncontrolled dampers. Inside the housing there is a small air filter (a piece of felt) and a check valve. The filter is needed to prevent small holes from becoming clogged with dust. And the reed valve is so that the damper rod has the ability to quickly extend when opening and slowly press when closing the throttle.

But most modern engines do not have this mechanical damper. Its role is played by the motor for forced increase in idle speed (Idle speed motor servo). For brevity, it is usually referred to simply as the idle speed motor (or idle speed control) (FIG37).

rice. 37

Rice. 37. The idle speed motor (2) bypasses the throttle valve and directly into the intake manifold, causing the engine speed to increase. This air enters through the hole (1) made in the throttle valve block. Therefore, it is easy to flush the entire idle system. It is enough to remove the air duct, start the engine and, with the engine idling, apply a stream of cleaner from an aerosol can into this hole. Since the engine tends to stall due to the over-richness of the fuel mixture, you need to maintain its speed with the throttle lever.

The most common types of idle motors are: The first type (used by Toyota in the series “G”, “J”, etc., “MMC”, etc.) has 6 terminals and contains four identical windings. The second type (“Toyota” series “A”, “S”, etc.) has 3 terminals and contains a magnet and two windings. Both types are pulsed electric motors, only the 6-output motor inside rotates the armature and it opens and closes a hole in the intake manifold through a worm gear, while the 3-output motor can only slightly turn its armature back and forth. But in this swinging armature (or rather in its continuation) there is a cutout through which air is sucked into the intake manifold. The third type of idle motor (used by Nissan, Mazda, etc.) is simply a solenoid, to which pulses are continuously sent immediately after the ignition is turned on. Depending on the duty cycle of these pulses, the solenoid core, overpowering its return spring, “hangs” in one position or another. Accordingly, it opens the hole in the intake manifold to one degree or another and thus changes the engine speed. An incorrect fuel mixture can be caused by leaking injectors (everyone has heard the phrase “injectors are leaking” in relation to diesel engines; the same can be true with gasoline engine injectors), a faulty ECU (every time it releases gas, it should completely shut off the fuel supply, literally narrowing to zero control pulses to the injector(s), faulty sensors (in this case, the ECU receives incorrect information about the state of the engine and, naturally, is not able to prepare the correct fuel mixture).So, when your fuel injected engine has a failure in the gas discharge , you need to do the following: Check the presence of the damper and its functionality. At approximately 1500-1200 rpm it should touch the throttle lever. In neutral gear (“parking”), spin the engine to 3000-4000 rpm and hold these revolutions for 15 seconds , then sharply release the gas pedal. The tachometer needle should immediately begin to fall quickly. But in the region of 1000-1100 rpm it should sharply slow down its fall, it may even stop, and then smoothly and smoothly drop to XX speed. This phenomenon exists - it means that the XX motor is in good working order and is working out its program correctly. No - you need to check whether the XX motor is working at all? To do this, with the engine running, turn on all the loads in turn: dimensions, headlights, heater motor, rear window heater. You can also turn on the air conditioning, but for many engines this triggers a separate device (a conventional solenoid valve) to increase the idle speed and release additional air into the intake manifold. So, if, when the loads are turned on, the speed does not increase, the device for increasing (stabilizing) the idle speed is faulty. Maybe dirt has accumulated in its channels, or because of a long stay, the XX motor (XX solenoid) has jammed, a defect has appeared in the connector, or one winding has broken. The latter is more likely for engines. If, when the load is turned on, the speed increases, and the gas release mode is processed incorrectly (without delay, with failure), you should check the serviceability and adjustment of the TPS. If everything is fine with it, the engine ECU is faulty. There have also been such cases (Nissan). The idle speed adjusting screw is fully tightened and the engine seems to have to stall, but it does not stall and runs quite confidently at XX speed. But this XX is ensured only due to the fact that the hole closed by the XX motor (solenoid) is completely open. After receiving a command from the ECU to increase engine speed, he would be glad to do this, but there is nowhere to go. The “hole” in the collector is already completely open. The fix is ​​simple. Unscrew the XX speed adjustment screw a couple of turns, and then start and stop the engine several times. If the ECU receives a signal to turn on XX, it will set the required speed using the XX motor (XX solenoid). Some factory instructions say that the XX speed adjustment should be done with the XX motor connector removed. Check the serviceability of the oxygen sensor (O2S), the tightness and serviceability of the injectors, and the fuel pressure. There may be too much condensed fuel accumulating on the inner walls of the intake manifold. This can happen because the intake manifold, for example, is too cold due to lack of coolant circulating through it. In general, the operation of the lean system very much depends on the state of the oxygen sensor, including in carburetor engines. In cars with an air flow sensor, for example engines of the 4A-GE type, it was possible to eliminate the failure of the gas at the discharge, as a result of which it even stalled, by adjusting the air flow sensor. These machines allow such adjustment. Even if there is no special adjusting screw, you can always open the MAF cover and loosen the spring.

Sergey Kornienko
Diagnostician , Vladivostok

The calibration hole in the throttle assembly is clogged

Pay attention to your throttle body. A small tube goes from it to the valve cover. This is a low ventilation hose. The calibration hole in the throttle assembly is often clogged with dirt and dust by drivers who neglect to replace the air filter. The problem can be resolved by cleaning the hole with a piece of wire. To do this, you need to remove the throttle assembly to prevent dirt from getting into the engine. It can be removed simply by unscrewing two 10mm bolts and disconnecting the throttle cable.

Fuel quality

One of the reasons is low quality gasoline, which does not meet the octane requirements for the car. The driver needs to remember where and what kind of gasoline the vehicle was last filled with. If it is indicated that the motor should run on AI-95 or AI-98, pouring AI-92 into the tank is dangerous.

The problem is caused by fuel - when you press the gas pedal fully, the speed does not pick up, and when the clutch is depressed, the power unit stalls. The situation is explained by the weak spark produced by poor fuel.

To fix the problem you need to:

1. Drain fuel.
2. Wash the motor.
3. Clean all fuel system pipes.
4. Change the fuel filter.

Car engines are sensitive to fuel quality.

Fuel pump is faulty

A fuel pump malfunction may be caused by oxidation of the wires in the connector. The power supply to the fuel pump is unstable, and, as a result, fuel is simply not supplied to the engine. This can be fixed by simply cleaning the contacts. There may also be a problem with the pump itself. Nothing lasts forever, and it can fail. But the most common fuel pump malfunction is contamination of the primary strainer. There is no point in washing it; it is better to buy a new one and replace it.

In this article, we looked at the most common reasons for the engine stopping while driving. If the information presented in the article does not help solve the problem, we strongly recommend that you contact a car service center.

What are the causes of car malfunctions?

If your car starts to have such a problem that it stalls as soon as it starts, then it’s time to take the car in for a technical inspection. In fact, there may be several reasons, and before identifying the true one, you will have to go through almost half of your car

What you should pay attention to first of all, we will consider further

1. The car alarm system is not working properly. Modern alarm systems that are connected to the central control unit have many additional gadgets that can negatively affect engine starting. Sometimes even electronics can malfunction and not work correctly. The auto program does not identify the start and stops the supply of electricity to the injectors, which, accordingly, deprives the spark (no ignition).
2. The idle speed control is inoperative. There can be two reasons for its incapacity - either it is too clogged, or it is not working and will need to be replaced. Poor quality fuel causes blockage and valve failure. Blockages clog the channels through which car mixtures along with oxygen must flow to the parts, this disrupts the ignition process.

To fix this problem, you will need the help of experienced specialists who will carry out ultrasonic cleaning.

Poor quality lubricants may also be the cause. Oil can remain on the cylinder walls and interfere with the normal stroke of the piston. To eliminate this problem, you need to change the oil after thoroughly flushing the engine. The fuel pump is unstable. The device will not have the necessary pressure for the system to operate smoothly, so the fuel supply will be intermittent.

1. Low quality fuel. This problem leads to engine detonation. The integrity of the heat pipes is compromised, and this leads to air leaks and dilution of the combustible mixture.
2. The gas exhaust system is clogged. Failure to remove excess gases will block the engine. This problem can only be fixed at a service station.
3. The fuel or air filter is clogged. If the filters are not kept clean, the system may also fail. It is necessary to monitor the filter parts and periodically clean or change them.
4. The oxygen sensor may fail and become one of the reasons that the car stalls. Correct operation of the sensor depends on the composition of the combustible mixture. If the composition is incorrect, the device will block further operation of the machine.

Poor starting when cold - reasons

If the Priora doesn't start well in the morning, it's quite annoying. When the car has cooled down to too low a temperature, the reasons for the engine failure to start may be:

• Congealed engine oil or discharged battery. As a result, the crankshaft will rotate too slowly.
• The water in the ramp could freeze - then the fuel system would literally stop. Pay special attention to the gasoline you fill up with - if there is a lot of water left after it, you should change the gas station.
• The coolant temperature sensor is broken (the ECU will not be able to regulate its temperature). The oxygen sensor may also be damaged.
• Fuel injectors are depressurized.
• The cylinders have low pressure levels.
• The motor control system is faulty.

Diagnose the operation of the ignition module.

Service visit

All the procedures that have been discussed can be done by a person who is familiar with car repairs. But, as a rule, beginners will not be able to find even the XX sensor. If you don’t have enough knowledge, then it’s better not to get into the engine and its system yourself, but to turn to specialists. Intervention on your own can only cause more harm. The cost of repair work in the service may vary. It all depends on why the engine stalls. Maybe it will cost by washing the parts, or maybe even more expensive engine repairs.

Why Lada Priora won't start - reasons

There are two cases when the car does not start at all - if the starter works or if it does not work. Both cases are negative, but the difference is that the signs of trouble to listen for and look for are slightly different. If the Priora starter does not turn, it is recommended to check the following points:

• The battery may be discharged. Charge it or, if you're short on time, borrow a working battery from a friend to test your guess.
• The battery terminals are oxidized or the wire terminals are oxidized. Check, ring the contacts, and then lubricate them with technical Vaseline. Finally, check the tightness of the terminals and, if necessary, tighten them.
• The engine or other components of the machine are jammed. The culprit may be the crankshaft, generator pulley or pump. We'll have to check all this.
• The starter is broken, the inside of it is damaged or worn out: the drive gear, the teeth of the flywheel ring. In order to determine the malfunction, you will have to dismantle and then disassemble it - only inspection of the parts can confirm the hypothesis. You don't always need to change the starter - just install a new part inside.
• Problems with the starter circuit. You will have to carry out diagnostics first while driving, and then look at it manually. Most often, the culprits are oxidized or loose wires, relays, or ignition switch.
• Starter traction relay malfunction. The diagnostic mechanism is no different from the previous version: turn the key to the second position, there should be clicks. The relay clicks and this is normal starter operation.
• Poor contact with the “minus”, the wires or contacts of the traction relay are oxidized. A click will be heard, but the starter will not turn. You need to ring the entire system, and then clean it at the connections, tighten the terminals.
• Short circuit or break in the holding winding of the traction relay. If this is the case, you will have to replace the starter traction relay. Instead of a click, a cracking sound will be heard when you turn the key, and the relay itself needs to be checked with an ohmmeter or touched, assessing the degree of heating.
• The problem is inside: the armature winding, the commutator, the starter brushes are worn out. You need to dismantle the starter and carry out diagnostics from the battery, and then with a multimeter. The freewheel is running slowly. The armature will rotate, but the flywheel will remain in place.

Visiting a car service center

In a situation where you specifically do not have enough experience in car maintenance, there is a fairly high probability of aggravating the problem by unqualified intervention in the operation of various on-board systems.

It is important to objectively assess your own capabilities, and if you don’t have faith in yourself, then it is better to entrust the repairs to specialists. In a situation where it turns out that the problem is not particularly serious, they will not take much money from you. But in any case, you will be able to avoid many of the troubles associated with unqualified attempts to repair the vehicle.

Route map for eliminating unstable XX on a VAZ 2170

Unstable idle is caused by the fact that the computer incorrectly perceives or does not know at all the amount of air sucked into the intake manifold. A typical treatment recipe looks like this:

• Check the sensors (IAC, DFID, TPS) and replace the faulty ones.
• Make sure that the adsorber valve is in good condition.
• If, after cleaning the throttle valve on the VAZ 21126 engine, the speed fluctuates, you need to make sure that there is no air leakage through the connections to the pipes.
• Check whether the diaphragm in the vacuum brake booster is intact.

The following problem often occurs: your favorite VAZ stalls when you let off the gas. VAZ is a simple car, and it won’t be difficult to figure out any problem. Yes, this also applies to other brands. You just need to know how the engine and fuel supply system work. By gradually eliminating all possible malfunctions, you can solve the problem of the car stalling while driving when you let off the gas. Where to start?

High voltage wires

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Current flows to the glow plugs through wires. It often happens that the engine stalls when the gas is released because one or two spark plugs stop receiving voltage. This reason becomes especially relevant in cold weather. The braided wires become tanned in the cold and tend to break due to vibrations in the cold. It can be treated by simply replacing the wires with better ones.

Fuel filter

A dirty fuel filter is another reason why your car stalls when driving. The part is installed on all vehicles. The problem with the device occurs among owners of used cars. The filter is forgotten and rarely changed.

Over time, the dirt fills up, it is difficult for gasoline to pass into the ramp, and there is no combustion chamber. Fuel will arrive intermittently, and then may not arrive. If the filter is clogged, the car stalls when you press the gas pedal.

You need to dismantle the fuel pump, remove the filter and install a new one. There is no point in cleaning it - the cost of the part is small.

Throttle valve

A dirty throttle body could very well be the cause. The Priora has difficulty starting when cold due to the supply of not clean air through the damper, but with various deposits. All this can prevent the preparation of a normal mixture in the correct proportions.

Sometimes the throttle valve can even get stuck due to the huge amount of deposits on it. To solve the problem, experts recommend cleaning the throttle - you can do this yourself using an injector cleaning spray.

Fuel pump

Due to a faulty fuel pump, the car may operate normally for a while, then stall. Interruptions begin in the mechanism, fuel does not enter the chambers or arrives in small quantities. Initially, the engine will run at idle, as the speed increases, it will stall, and when the pump finally fails, it will not start.

The fuel pump is easy to repair, but the breakdown may recur, so it is better to replace it. This unit is located under the rear seat.

In summer, the fuel pump may operate intermittently due to fuel boiling. This happens on classic Soviet cars. To get rid of the problem, you have to turn off the engine and wait until the fuel cools down.