What does it mean, the engine is tripping. Why the engine stalls: causes of problems. Why does the engine stall, what does it mean and how to find the cause? When accelerating, the engine starts to stall.

06.11.2021

In the past, most cars had a four-cylinder engine. There were cases when one of the cylinders failed, and then only three cylinders worked. This is how the expression “troit” appeared. What does it mean to troit an engine? This malfunction implies incorrect operation or complete inoperability of one or more cylinders in the engine.

Symptoms of a problem

How can you tell if the engine is leaking? Each driver can determine this problem independently. To do this, just pay attention to the behavior of the car. There are a number of signs that indicate a problem:

When the engine is running, constant sounds appear, as well as strong vibration at idle.
The spark plugs in one of the cylinders are heavily smoked and covered with a large layer of soot.
When accelerating, slight jolts and jerks are felt.

All of the above signs can indicate not only tripling, but also other problems. If you encounter them, it's time to diagnose your car.

Key causes of failure

One of the most popular questions is, why does the engine stall? There can be a huge number of reasons, and diagnosing each individual part will require time and effort. However, four main directions can be identified that lead to tripling:

ignition system problems;
malfunction of the fuel supply system;
power system problems;
reduction in compression due to wear of the cylinder-piston group.

How to determine a bad cylinder

When carrying out repairs, it is very important to identify the problematic cylinder. There is a proven method for this, which is used by many automotive specialists. It involves removing the armor wires from the spark plugs one by one. The procedure for determining an inoperative cylinder consists of the following steps:

Find a dielectric base to stand on during the procedure. This can be a thick rubber mat or a wooden board.
Start the engine, and then keep the speed around 1500.
Take the wire itself (not the cap) and disconnect it from the spark plug. If the sound of the engine has changed, then the cylinder is working.
Reinstall the wire and then follow the previous step for the rest. If the engine sound does not change when disconnected, then you have found a faulty cylinder.

Problems with spark plugs and wires

Can the engine stall due to spark plugs? It's over, yes! This is the thought that first comes to mind for motorists. Late or early ignition, as well as a too weak spark, can lead to the problem described above. Drivers need to dismantle the spark plugs and check the integrity of the entire structure. Damage to the insulating material is immediately visible to the eye.

Soot on the spark plugs also indicates a problem. A mixture containing too high a concentration of gasoline is supplied to the cylinder. A layer of soot leads to interruptions in the operation of the candle. It can form for several reasons:

The motor is constantly subjected to prolonged warm-up.
Cylinder compression ratio too low.
The timing belt has moved one or more teeth.
Problems with the injector or carburetor.

If the engine stalls when cold, but the spark plugs are fine, inspect the wires. A sign may be the appearance of tripling during high humidity or after rain. It is the violation of the integrity of the armored wire that causes the engine to stall after washing, but all the symptoms completely disappear after some time. If the engine is running hot, it is necessary to inspect the cylinders and piston rings.

Air System Inspection

Excessive or insufficient amount of air in the intake is one of the most common causes of engine tripping. The system may lose seal, causing the engine to draw in more air. It is quite possible to check the air system in garage conditions. To do this you need to do the following:

Close the intake pipe near the air filter.
Start pumping air to create a pressure within half an atmosphere.
If the pressure drops, then the system is not completely sealed. This is where you need to look for a leak.

A lack of air can be caused by a clogged air filter. It must be changed in a timely manner.

Is it possible to drive if the engine is not working?

In addition to noticeable discomfort, tripping can lead to serious damage, the elimination of which will require you to spend either your personal time or money from your wallet on car service services. The fuel-air mixture will continue to flow into the non-working cylinder. Gasoline will gradually settle and enter the crankcase. The oil will lose its characteristics, become liquid and will not be able to perform its functions.

The consequence will be a decrease in engine compression, various scuff marks on the metal due to insufficient lubrication, and accelerated wear of components. The engine will not only run dry, but also at higher temperatures, since the oil also removes heat. Guaranteed increased consumption fuel and unstable operation of the internal combustion engine.

If you do not want to carry out expensive repairs, then you should definitely look for the cause of the tripping and then eliminate it. Some problems can be fixed on your own in the garage, while others require professional intervention.

If you, in the company of your friends, say that your engine is missing, they may misunderstand you or simply look at you with “square” eyes... It’s another matter if you complain that the engine is missing or one of the cylinders is not working, in which case a large number of different versions and assumptions allegedly taken from personal experience, as well as advice on what to do in this case. You can, in principle, listen to the advice of friends, there is nothing wrong with that, but I would also recommend listening to the opinions of experts on this matter. In my article today, I will talk about what engine tripping is and where it comes from, you will learn about the causes of this unpleasant phenomenon, as well as ways to eliminate this malfunction. Armed with the information I needed, I decided to visit the mechanics at one popular bus station in our city, in order to find out whether the various “experts” wrote on the forms were true and whether they should be trusted. Simply put, I decided to ask why the engine troubles those who are directly related to this.

Let's start with why the engine triples, and not “double” or “quadruple”, for example:-)

The fact is that quite recently most engines had four cylinders, probably no one would have believed that there could be six, eight or twelve 30 years ago, but oh well... In general, when one of the four cylinders stopped working, then there were only three working cylinders left, and the sound of the engine changed seriously. This phenomenon is called engine throttling, that is, the engine runs on three cylinders with a characteristic sound. Years passed, the number of cylinders changed, but the term troit remained unchanged.

How can you tell if the engine is leaking?

Personally, it seems to me that tripling cannot be confused with anything else. This sound will be immediately audible, it’s as if your car is being replaced and it starts working like an old Cossack with some kind of vibration and “rattling”. Instead of uniform synchronous operation of four cylinders, some kind of intermittent bubbling is heard. In short, it's difficult to describe. In this case, instead of a smooth hiss, a “bang” will be heard from the muffler.

What are the consequences of tripling?

First of all, you will lose power no matter how you look at it, and the engine will not run on three cylinders as well as on four. Everything seems clear here. The second sign that the engine is malfunctioning is vibration and a characteristic “trembling” that comes from engine compartment. Third characteristic feature The only problem with the engine is excessive fuel consumption and the smell of gasoline in the exhaust gases. Do you think that's it? No, as they say, this is just the beginning; if the fault is not detected and corrected in time, big trouble awaits you.

I'll explain why. When one cylinder does not work, combustion of the fuel-air mixture does not occur in it, which means it all accumulates in the cylinder, then, diluted and mixed with oil, goes into the crankcase. The more fuel goes into the crankcase, the more the oil will be diluted, its viscous and lubricating properties will completely disappear over time. As a result, you will get a significant reduction in compression, critical wear of the piston and rings, which will rub in the combustion chamber without a drop of lubrication, creating scuffing and abrading the cylinder walls. In the end, engine overhaul is simply inevitable.

Reasons why the engine may trip

You already know how tripling occurs, but the problem still lies in some kind of malfunction, which causes the cylinder to stop working. Unfortunately, there can be several reasons why an engine is misfiring, which seriously complicates the search.

So, to your attention the most common causes of engine tripping

First of all, let's start with the non-working cylinder:

Start the engine and open the hood.
Listen to the engine and try to remember it.
Next, we take out the high-voltage wires one by one. When the wire is pulled out, the engine operation should change, because the spark plug stops receiving current, therefore the cylinder stops working. If the engine operation has not changed, then this is a bad cylinder. You need to search until you find which cylinder is not working.
Now, you need to find out whether a spark is entering the cylinder or not, this will allow you to understand the reason, and also indicate the direction in which you need to move.

Now you need to check the spark plugs, for this

Take a spark plug and unscrew the spark plug in the non-working cylinder.
Assess the condition of the electrode using the following criteria:

Soot or soot on the spark plug prevents its normal operation, the spark is weak or completely absent. Whether cleaning the spark plug will only temporarily solve the problem, you need to look at the root of the problem and continue to look for the reason why the spark plug is in this condition.

Checking the spark plug for a spark

To find out the real reason why you need to check the spark. To do this, unscrew the spark plug, then put on the high-voltage wire and place the spark plug with its metal body facing the engine, but the spark plug electrode should not touch the engine. Next, you will need an assistant, he should turn the starter, and in the meantime you watch the spark plug. If a spark does not appear when the starter rotates, move it away from the ground by 1 cm and try again.

A weak spark or its complete absence indicates the following:

Problems with high-voltage wires - high resistance or breakage. using a multimeter, in case of high resistance, replace them.
The ignition coil is faulty - check if this is the case and replace it if necessary.
The ECU is faulty. Carry out diagnostics and replace if necessary.
The DPKV (crankshaft position sensor) has failed. As a rule, when such a breakdown occurs, an error appears, which is displayed on-board computer, you can also find out about it on computer diagnostics. If needed .
Shifted several teeth. Check how the belt is positioned; if its position is broken, remove the belt and adjust the position of the shafts and gears according to the marks.

If there is a spark and the spark plugs are in perfect order, look further for the reasons why the engine is misfiring; possible problems may include: compression problems, faulty rings, clogged injectors, poor valve fit or the need to adjust the valves.

Sometimes there are cases when the engine only starts “cold” or “hot”

In this case, the valves are most often the cause; they may have become misadjusted. should be carried out every 20 thousand km. The essence of this problem is that most likely the valves have large gaps, but after the engine warms up they become smaller and the engine does not leak. The same applies to “hot” conditions - when the engine is cold, the valves are normal and the engine is running smoothly, but after warming up, the unregulated valve is clamped, as a result, the cylinder stops working and the engine begins to stall.

I will end here, I hope my article was useful to you and you found the reason for the engine tripping. If not, seek help from specialists. If you know other reasons for engine tripping, I’ll be happy to hear them, use the comment form.

When various malfunctions begin to appear in the engine, accompanied by uncharacteristic sounds, it does not immediately become clear where the strange noise came from and what it means. The engine is malfunctioning - this is exactly the diagnosis that specialists from a car repair shop can make. To successfully get rid of the tripping sounds, you need to follow the instructions.

general information

Engine internal combustion is a highly complex system that requires regular maintenance and repairs. In the absence of such procedures the risk of failures and malfunctions in the operation of the unit increases:

There are many reasons for such malfunctions, but one of the most common is tripling. The defect occurs on almost all types of power plants (diesel, gasoline), with any mileage, condition and other operating properties of the internal combustion engine.

And if the engine fails, but the driver does not take appropriate measures, this leads to irreversible consequences in the form of failure of the unit. To avoid this, it is important to eliminate the source of the problem in a timely manner.

To ensure that the engine operates normally and the combustion of the fuel-air mixture occurs correctly, it is important to maintain its tightness. If leaks and damage to the CPG and timing belt appear, the gas distribution mechanism will begin to fail, which will increase the risk of complete depressurization. Loss of tightness occurs when piston rings, piston, cylinders and other important components of the system become stuck or deformed. It is also caused by the appearance of cracks or burnt out timing valves.

To determine the malfunction, it is important to measure the compression in the cylinders. If the level has dropped in only one cylinder, then it is enough to pour a little motor oil using a syringe. After performing such a manipulation, you need to take a second measurement.

Main reasons

To troubleshoot the problem, you need to figure out why the engine is shaking. The reasons are often related to disruption of the combustion process of the fuel-air mixture in the cylinders, which causes severe vibration. But the occurrence of vibrations is not always associated with tripping, because there may be other factors that contribute to such symptoms. The reasons why the engine starts to stall include:

Shortage or excess fuel mixture, which is fed into the cylinder.
Lack or excess of air.
Failures causing early or late ignition.
Damage, wear and other engine breakdowns accompanied by loss of compression.

In most cases, tripling occurs when the wrong fuel composition is used, untimely ignition, or the inability to ignite. This is also facilitated by incorrect combustion conditions due to mechanical damage or other failures in the operation of the internal combustion engine.

Considering these data, you can significantly narrow the search range and the number of diagnostic devices. It is imperative to check the fuel system and injector, after which the intake air supply is assessed. In some cases, engine stalling occurs when one of the ECM sensors is damaged.

One of the common problems that cause tripping is late or early ignition. Also, the engine may stall if the spark plug is weak, which is easy to fix on your own. First of all, you need to unscrew the spark plugs and inspect them in detail. If there is damage to the insulator or other visual defects, the spark plug will have to be replaced.

If the insulator is damaged, it will be visible to the naked eye, because the damage site will be covered with a black coating. In addition, it is necessary to assess the condition of the central electrode and carefully examine the gap of the side element.

At the next stage, it is recommended to check the spark plug wires. If occasional tripping is noticed when driving in rain or high humidity, this unit may stop working normally. The power plant will need to be warmed up and returned to normal operation.

You need to start work with a visual inspection of the spark plug cap and the wire with maximum voltage. Such components are covered with an insulating layer, which dries out over time and begins to crack. This results in current leakage.

High-voltage wires are subject to malfunctions during frequent repair or service activities under the hood. It is almost impossible to determine the defect visually, so you will have to contact a specialist for help.

If the spark plugs and wires are completely intact, the cause of the tripping may be the ignition coil. And if the engine contains separately placed components, the phenomenon will spread to each spark plug. To check the coil, just unscrew the spark plug, apply it to ground and start the engine. It is important to make sure that the thread of the candle fits tightly to the mass and that the cap is securely fixed to the candle. If you do not follow the rules, the coil may burn out and the switch may fail.

If a good spark appears with a bang, you will have to look for another reason for the tripping. If there is no spark, the coil needs to be replaced. The electronic ignition distributor or switch rarely breaks down, so there is practically no need to replace it.

Improper air supply at the intake also leads to intense engine vibration. In this case, the risk of depressurization increases, due to which the power plant will suck in excess air, reducing overall power and stability.

To check the air system, you need to close the inlet pipe near air filter and start pumping air to ensure the required pressure (usually it is 0.5 atmospheres). Then you should start looking for the leak. If there is no pressure drop, it means the system is fully operational. If there are hissing sounds in any place, the unit will most likely need to be repaired.

As for the lack of supply air, then it is often caused by filter contamination, due to which it lost its capacity. Fixing the problem is very simple: first of all, you need to remove the filter, and then check how the engine works without it. In addition, the problem also appears when the throttle valve becomes clogged. Such an element requires careful diagnostics and testing, so they must be performed at every scheduled technical inspection, along with changing the oil, filters and other operating elements.

Often, engine stalling is caused by a damaged TPS, mass air flow sensor or other sensor that sends an incorrect signal to the electronic control unit. As a result, the last unit cannot determine how open the damper is and how much air mass has entered the motor. As a result, the remaining components power plant are not able to correctly calculate the composition of the fuel-air mixture, which entails additional problems.

To verify that the sensors are faulty, you need to check the operating mode with a scanner installed in the diagnostic connector, and then compare the received data with the nominal ones. Any deviations from the norm lead to the beginning of the engine tripping.

Damage to the power system

If the engine starts to stall, it may be due to damage to the power system. Checking it for faults, It is important to familiarize yourself with the operating properties:

fuel pressure;
suction intensity.

The first indicator is related to the functionality of the electric fuel pump, which is installed in fuel tank majority modern cars. If the filter mesh becomes clogged with all kinds of debris, this causes malfunctions in the electric motor of the fuel pump or impairs the power supply to the device.

At the inspection stage, you also need to assess the condition of the regulator valve in the fuel rail. If the pressure is too low, tripping is inevitable.

After checking the previous components, you need to evaluate the condition of the injection nozzles. As you use it vehicle they become clogged, which reduces throughput and leads to other failures. In addition, the injectors can completely fail. To clean and check them, it is necessary to use a washing stand that pumps a special cleaning compound and also supplies power. The system simulates the operation of a working injector and evaluates performance.

If the nozzle is not damaged, then when closed it should not leak. In addition, the injection system must open in time when an electric pulse is applied.

If there are no problems with fuel pressure and injector operation, all that remains is to assess the condition of the ECU. And although such an element fails in very rare cases, it is possible. The cause of the trouble is replacing the factory firmware or software chip tuning.

If you flash the fuel map incorrectly, this will lead to such trouble that the electronic control unit will begin to overflow fuel. Problems in the form of flooded spark plugs are also inevitable.

If engine compression readings have dropped significantly, this may be due to engine wear. Often one or a pair of cylinders fail, resulting in incorrect compression of the fuel-air mixture. Because of this, normal fuel combustion does not occur, and compression drops due to burnout of pistons and valves, wear of piston rings and other problems.

To fix the problem, you need to evaluate the compression in the engine, and then disassemble the unit for detailed diagnostics and repairs. In any case, the motorist must understand that starting the engine with a faulty cylinder is strictly prohibited. If you ignore this rule, additional failures and problems are simply inevitable. The final repair of the system will require large financial costs and effort.

The list of reasons for engine tripping is very extensive. But in order to understand why the car misfires and how to deal with it, it is important to separately consider the type of power plant (injection or carburetor), the specifics of the timing belt, the general condition of the engine, and others. If we are talking about problems with a carburetor engine, then perhaps the problem can be eliminated by simply cleaning and adjusting the carburetor.

For injection-type models, additional diagnostics, restoration of sensors, cleaning of injectors and other service measures will be required. If problems with the internal combustion engine itself have caused the engine to trip, you will have to prepare for mandatory disassembly of the engine for thorough diagnosis and repair.

In any case, if the engine starts to stall, this is a serious signal that diagnostics need to be performed. In this case, it is important to quickly determine whether there is a problem, and also select effective method its elimination.

Enough frequent malfunction is unstable operation of the engine in idle mode, during so-called throttle changes, and also when the speed while driving is low. In this case, the driver begins to feel increased vibrations on the steering wheel, gearshift lever and body.

In other words, the car shakes a little because . In fact, the concept of “troubling the engine” should be understood that one or more cylinders do not work, that is, the fuel-air mixture in them does not ignite, does not ignite in a timely manner, or the combustion of the charge does not occur in full.

Moreover, if the speed is increased to XX or when the engine is under load (while driving), the work power unit normalizes, twitching disappears, the motor runs smoothly and stably. Next, we will look at why the engine stalls at idle and what the driver should do in such a situation.

Read in this article

The engine stalls at idle: common causes and quick diagnosis

It is quite obvious that with such a malfunction it becomes difficult to operate the vehicle, since you have to constantly increase the speed to maintain normal operation of the internal combustion engine. As a result, fuel consumption increases noticeably, it can also become very difficult, etc.

At the very beginning, you need to determine which cylinder is not working. To do this, start the internal combustion engine, and then disconnect the high-voltage wires from the spark plugs one by one. If after disconnecting the power the engine operation changes, this means that the cylinder is working. Turning off the power from the non-working cylinder, on the contrary, will not lead to a change in the sound and nature of the operation of the power unit.

In some cases, replacing the spark plug or cleaning it allows you to normalize engine operation and get rid of “triple”. It should be remembered that although spark plugs can be designed for 30-80 or even 100 thousand km. mileage, when driving on domestic fuel it is often necessary.

It is also important to consider that when checking high-voltage equipment, you need to follow safety precautions. If you have no experience, then it is advisable to put a wooden block, rubber mat, etc. under your feet. Also, when disconnecting the wires from the spark plug, do not hold onto the cap. You need to grab a high-voltage wire. In this case, you should try not to touch the engine and car body.

At the same time, it should be understood that armored wires can also be damaged and penetrated. By the way, if the spark “goes somewhere”, in the dark it is enough to look under the hood to detect a breakdown.

Let us add that on engines with direct fuel injection there is no need to disconnect the wires, since it will be enough to disconnect the fuel supply control chips from the injector, identifying the problem cylinder by changes in the operation of the internal combustion engine.

Please note that when a diesel engine is running, to check it is necessary to alternately turn off the supply of diesel fuel to the injectors. To do this, unscrew the fittings on the high-pressure lines.

Now let’s imagine that the required cylinder has been found, the spark plug gives a spark, the armored wire is in perfect order, and the engine still runs rough. In this case, you need to unscrew the spark plug again and inspect the tip, determining whether it is wet or dry. As a rule, this will indicate problems with mixture formation.

If the spark plug is wet, then the air/fuel mixture may be too rich. A dry spark plug indicates that the mixture is too lean. In both the first and second cases, the cylinder will not work on such a mixture, even if the ignition system is working. The cause may be contamination or damage to the injectors, as well as the leakage of excess air.

As part of the diagnostics, you can perform a quick check of the injectors by disconnecting the power plugs from them. If when you turn off the power from any injector the engine operation does not change, then this is a faulty element. To confirm or refute this, swap this injector with the one in the adjacent cylinder. If the cylinder operates normally, then the problem is not the injector.

I would also like to note that tripping can be caused by a more serious reason - a decrease in engine compression. In other words, we are talking about problems with valves and/or CPG. In this case, low compression often occurs in only one cylinder. To determine this, you need to know.

Finally, it should be remembered that the injection engine also fails in many cases due to damage or failure of coils, switches, sensors, incorrectly positioned, etc. In some cases there may be no spark, in others there is a spark and everything is fine with the fuel supply, but tripping is still present.

In such situations, it will be extremely difficult to solve the problem yourself, especially on the road. It's better to go to . For example, a failure or incorrect signal from the (mass air flow sensor) is often the reason why the engine runs rough and idles.

As you can see, if the engine stalls at idle or at low speed, the reasons may be different. At the same time, it is important to understand that malfunctions in the operation of the distributor can also lead to disturbances during the operation of the internal combustion engine, but in this case the engine will often fire on all cylinders in turn.

It is also important to understand that usually the engine rarely starts to stall severely without other symptoms that preceded it. Typically, common symptoms include problems with cold starts, smoky exhaust, excessive fuel consumption, etc.

In some cases, refueling is enough to solve the problem. quality fuel, warm up the engine well, then drive for 15-20 minutes at high speeds. In others, you simply need to replace the armored wire. However, unfortunately, these simple methods don't always work.

Often, deviations in engine operation are already a reason for replacing not only spark plugs and filters, but also checking the fuel pump and fuel pressure, as well as conducting computer diagnostics. If the problem is not corrected in a timely manner, the malfunction will progress, which often leads to costly and complex repairs in the future.

Prerequisites for engine tripping

What is engine tripping? This is a malfunction of the engine, which entails partial or complete disruption of the operation of one or more cylinders. In other words, if the air-fuel mixture in the cylinder begins to burn poorly, or stops burning altogether, this is triple. It looks like there is vibration in the engine and it is ready to jump out of its mounts, but the engine does not move. You may also encounter characteristic pops in the muffler, which are essentially fuel flashes, that is, the mixture caught fire, but it did so too late. The engine can jam either constantly or from time to time.

Reasons for tripling

In fact, the reasons are banal:

Too much or too little fuel enters the cylinder
there is too much or too little air in the cylinder
the ignition spark passes too early or too late
compression is too low, causing the fuel to operate at the wrong pressure

Knowing these reasons gives you a basis for looking for problems. First of all, you need to check the ignition system and air supply system. The following describes the troubleshooting algorithm in the order in which it is necessary to look for the problem.

Ignition spark passes too early or too late

We need to start with this. The most common cause of tripping is a weak or untimely spark. The reasons for the ignition failure will be given below:

Violation of the integrity of the spark plug insulator - a spark plug is a metal rod, an insulator around it and a mass that is located in the same place as the thread. The insulator is ceramic and can burst due to temperature changes or mechanical stress. The breakdown site is usually smoked and is clearly visible. The cost of diagnostics is 0 rubles - just remove the cap from the insulator and inspect the spark plug from all sides.
Violation of the integrity of the insulation of the spark plug cap or the insulation of a high-voltage wire - the insulation is made of rubber or silicone and is quite easy to damage mechanically. The insulation also dries out and breaks through. It’s quite easy to check - in the dark, spray the wires and caps from the plant sprayer with plain water - if “lightning” or sparking appears, then there is a breakdown. The cost of diagnostics is 0 rubles. Usually, with this malfunction, the engine does not start constantly, but rather in fits and starts, and more often in wet weather.
Failure of ignition coils - this happens quite often, especially if the coils for each spark plug are installed separately. It's easy to check - remove the spark plug, place it on ground and start the engine. If there is a spark and it clicks, then everything is in order, otherwise the coil is not good. Attention! Carefully ensure that the thread of the candle lies very tightly to the mass, and that the contact of the candle with the cap is reliable. Otherwise, the ignition coil or switch may burn out. If checked correctly, the cost of diagnostics is 0 rubles.
Failure of the switch (electronic ignition distributor) is quite rare. You can check by pulling out the caps and connecting them to spark plugs that are well secured to the ground. On command, your partner turns on the ignition and tries to start the engine, and you listen to see if all the spark plugs give a spark, and if all the spark plugs click. The cost of diagnostics is juice for a partner.
Failure of spark plugs - rolling a spark plug is quite difficult, but it is possible. If the central electrode of the spark plug has a lot of wear, then the gap increases greatly, and if there is a spark, it is very weak. You can check by visually inspecting the spark plugs. The cost of diagnostics is 0 rubles.

There is too much or too little air in the cylinder

First, you need to check the air supply system for leaks, resulting in air leaks. Checking the air system for tightness is simple: close the intake pipe as close as possible to the air filter with something of a suitable size, for example, oil filter and through a vacuum hose we pump up a pressure of about 0.5 - 0.7 atmospheres with a compressor, and listen to where the hissing is. If the pressure holds, then it’s good, if there is a hissing, there is a leak through which excess air enters, and the engine is not able to cope with the problem and begins to stall.

Low air may be due to a clogged air filter, or a malfunction in the air supply system dampers. The first thing to check is the throttle valve.

It may also seem to the engine control unit that there is not enough air, or a lot of air, or even that the damper is open to a different degree than it actually is. This is where engine diagnostics via a diagnostic cable will come to the rescue. Only now you need to not just count errors, but look at the values of the sensors that go to the “brains” and compare them with standard values. The engine will stall if the values of the air flow sensor or throttle position sensor differ from the actual values.

Too much or too little fuel enters the cylinder

Here the situation is very similar to air. The first thing to do is check the pressure in the fuel system. It is not expensive, but provides more than enough information. If the pressure is low, either the fuel pump or the fuel pressure valve in the fuel system is at fault. The pressure relief valve or discharge part of the pump may fail. Because of low pressure, less fuel will be supplied than necessary, which will cause the engine to stall.

If the pressure is normal, it’s time to check the injectors - they may be dirty or out of order. The easiest way to check the nozzle is to connect it to a bottle of carburetor cleaner, and briefly connect the wires through the light bulb to the battery terminal. That is, you will simulate a pulsed current supply to the injector, and the tank will simulate fuel pressure. If an injector leaks or, on the contrary, does not open, it should be replaced, although current injectors can sometimes be revived on a washing stand. The injector can also pour fuel in a stream rather than spray - this is also a reason to at least try to wash it.

Well, the engine control unit completes the fuel epic. It may seem to him that more fuel needs to be poured, and he will try to fulfill the plan, while filling the spark plugs, and at the same time the engine will throttle.

Compression too low

This is a sad point, since often you can’t get by with a little bloodshed, but in fairness it is worth noting that the reason is not the most common. Low or zero compression can occur due to burnout of the piston, valve, or fatal wear of the piston wheels. The first two reasons are more common with triplets.

The only effective way to find the causes of a drop in compression is to disassemble the engine and troubleshoot it. Usually such problems one way or another lead the owner to.