A car engine may not start well when cold under different conditions. Sometimes it happens that the car has been parked in the garage or outdoors for a long time. A situation may also arise when the engine worked, then cooled down, and it will not start again.

Starting problems that occur on a cold engine may not appear at all during a hot start. When starting a cold start, it is also important to consider the ambient temperature at which you are trying to start the vehicle. In cold periods, some elements simply freeze, so starting the engine in such conditions is simply impossible.

The main reasons for poor cold start

There are several main reasons why starting a cold engine will be difficult or even impossible. To understand what is the cause of the malfunction, it is necessary to conduct a thorough diagnosis and localize the breakdown. First you need to check the battery, it is possible that it is completely discharged. Further, it is necessary and rotates the engine at the same speed. If you fill up with low-quality gasoline, then this can also lead to the fact that the engine of your car will not start well when cold.

Fuel supply problems.

Cold start problems appear when there is no combustible mixture (fuel) supply. Fuel can be supplied in very small quantities or in very large quantities. When there is too much of it, the spark plugs will be flooded and fail. In some cases, the fuel can be supplied normally, but the ignition of the mixture in the engine cylinders themselves does not occur or does not occur in a timely manner.

The fuel system check must begin with an exhaust check. If, when the engine rotates with the starter, a small amount of smoke comes out of the exhaust pipe, this indicates that ignition processes are taking place and fuel is supplied to the corresponding engine cylinders.

After that, you need to check the spark plugs. To do this, take the appropriate key and simply unscrew them. If they are filled with fuel, then this indicates an excess of fuel in the cylinders. This can occur as a result of a leak in the injectors or a faulty ignition. If the candle is completely dry, then this indicates that no fuel is supplied to the cylinders at all. It is necessary to check the performance (spark) of all candles.

Poor supply of the fuel mixture to the cylinders can be caused by clogged fine and coarse filters. A kind of plaque can form on the injector nozzles, which prevents the normal flow of gasoline. The fuel supply may also decrease due to breakdowns of the fuel pump. In most cases, the gas pump simply does not create the right pressure. To eliminate this malfunction, it will need to be completely removed and disassembled to eliminate the causes.

It will also be necessary to check all fuel lines for cracks and other damage through which air can enter the fuel system. This can be easily identified by the leaks.

Problems with electronic sensors.

Modern gasoline vehicles are equipped with fuel injection systems that inject fuel electronically. These systems are equipped with a variety of special sensors. If a breakdown occurs with one of these sensors, the corresponding signals will not be sent to the main control unit, as a result of which the engine will stop starting normally.

First of all, you will need to check the following three sensors:

• DPRV sensor, which indicates the correct location of the camshaft;
• TPS sensor. It gives signals about the main positions of the damper;
• The DMRV sensor, which indicates the air flow in the system.

Ignition problems

When faults appear in the ignition distributor, this can lead to the fact that the engine will not start well when cold. The essence of this malfunction is that the starter rotates the engine, but seizing does not occur and the fuel in the engine cylinders does not ignite.

It is very important to set the ignition timing correctly, for each car brand, this angle will have its own meaning. It is also worth checking the condition of the drive and timing belt, as well as adjusting the valve timing, if any. You will need special tools and fixtures to check.

Starts badly on cold: nengine compression problems

As a result of prolonged operation of the engine, some of its elements may become unusable, as a result of which the compression in the cylinders will begin to fall. An engine with low compression is very difficult to start because all the clearances between the main parts in the cylinders increase significantly. This leads to the fact that the required pressure is not generated in the combustion chamber, which is necessary for starting.

The following reasons lead to poor engine compression:

• Piston cracks;
• Damaged piston rings;
• Wear of the engine cylinder itself;
• Burnout valves.

In cold conditions, an engine with poor compression is simply impossible to run cold.

Let's sum up

In this article, we have discussed the most basic reasons why the engine may start poorly on a cold one. As you can see, there are not so many of them. Therefore, it will not be difficult even for a beginner to independently determine what the malfunction is. First of all, check the condition of the spark plugs, injectors and contacts with the sensors. If everything is normal, then you need to check the pressure that the fuel pump creates and the performance of the sensors. As a last resort, if all else fails and the problem cannot be solved on your own, contact a specialized service.

The device of the injector, thanks to the ECU and various sensors, is more complex, and therefore there are more vulnerable links in such an engine compared to a carburetor engine. It is more difficult to find the source of the problem. It so happens that a car with an injector does not start well or does not start at all (if the carburetor does not start, and also if the diesel engine does not start). What, then, should be checked in the first place?

GASOLINE PUMP

A characteristic sound comes from a working, working gas pump. If there is a suspicion of its malfunction, then this suspicion can be confirmed or refuted by checking the spark plugs: if they are dry, then the matter is in the gas pump. What is out of order in the fuel pump - wires, fuse or relay - remains to be seen. How to check a gas pump

First, we check the integrity of the wires suitable for the gas pump, whether they have oxidized. For this, other, new wires must be connected directly from the battery to the gas pump. If the fuel pump works normally with them, then you need to change the standard wires.

If everything is in good condition - the fuse, relay and fuel pump wires, but the latter, nevertheless, does not work, it remains to conclude that the fuel pump itself has become unusable and requires replacement (replacing the fuel pump with a VAZ). Again, in order to check the serviceability of the fuel pump, you need to connect it to the battery directly, or, instead of it, connect a working fuel pump.

Video: The VAZ 2110 fuel pump (injector) does not work, we are looking for the reason

RAMP PRESSURE

It happens that the injector does not start due to the lack of sufficient pressure in the fuel rail (normal - it should not fall below 2.8 kg / cm²). This can happen if the fuel pressure regulator is malfunctioning.

A dirty fuel filter will also prevent the normal pressure in the fuel rail. It is better to change the fuel and air filter more often.

CRANKSHAFT SENSOR

This is the only one sensor, in case of malfunction of which the engine does not start at all. If any other sensors fail, the operation of the injection engine only deteriorates. How to check the crankshaft sensor

NOZZLES

As you know, injectors fall into disrepair one by one, and nothing terrible will happen for the engine if only one injector does not function. Even worse (there will be triplets), but the engine will work.

To calculate the faulty injector, you need to start the engine and touch the exhaust manifold pipes. A pipe that turns out to be colder than others will indicate a cylinder that is not working. By the way, the cylinder may not work not only due to the injector, but also due to the fault of a plug that is out of order. In this regard, if a faulty cylinder is identified, then you need to check its spark plug.

IGNITION SYSTEM

In an injection engine, you need to check the ignition module and spark plugs.

If the injection engine does not start, the cause may be unregulated ignition. There is a very simple way to install the ignition.

GAS DISTRIBUTION SYSTEM

Unadjusted valves, by themselves, are usually not the reason that the engine will not start at all. If the valve clearances are out of order, the engine will start, but it will simply work worse. A serious problem for starting the engine, unregulated valves can be, in combination with some other malfunction. If there are not one, but several problems (including incorrect valve clearances), then the engine may not start. So adjusting the valve clearances can help eliminate this problem (how to adjust the valves).

Also, the engine does not start if an error was made when installing the timing belt (how to set the timing marks).

Perhaps these articles can also help you solve the problem:

Video: Why the injection car does not start

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Modern cars are gradually moving from the concept of mechanisms to the concept of organisms. It is a highly complex system that needs ideal working conditions. High engine power, squeezing out everything that can be squeezed out of technology, and other features of the modern car industry indicate that modern cars must receive maximum care in order to work for a long time. One of the common problems associated with improper machine care is poor engine starting after warming up. This means that if you park for a few minutes near the store, you will not be able to start the engine normally. The problems lie in two possible breakdowns, but there are also extraordinary cases. Today we will deal with the most common tasks in this case, and also talk about private options for problems.

It should be noted that the symptoms of a poor hot start can manifest in different ways. One car generally refuses to start until the engine has cooled down. Another power unit starts only on the third or fourth attempt, and the third one simply has to be twisted for a long time to start. In any case, no matter what happens to your car in this context, you need to find the problem and be sure to fix it. This task is a harbinger of more serious damage, which will cost you much more money to fix. So let's see why the car does not start well when hot.

Poor fuel or additives in the fuel mixture

Poor quality gasoline or diesel fuel is one of the most common variants of this problem. But in this case, you can conduct an experiment that shows the true problem of your car. The fact is that low-quality fuel with a poor start to hot will have an even more unpleasant effect when starting the engine to cold. Therefore, it is enough to cool the car, wait for the engine to return to normal and start it. Also, there may be the following problems with fuel:

• gasoline or diesel fuel may contain an additive that your engine will not accept;
• diesel fuel has frozen and acquired a jelly-like form that is difficult to pump;
• there are solid particles in gasoline, filters are clogged, and it is difficult for the pump to pump the required amount of fuel;
• the settings of the engine management system and air supply are out of order, one of the valves may have broken;
• the idle valve, as well as the mass air flow sensor (mass air flow sensor) can cause such problems;
• just a functional feature of carburetor engines - a very hot unit does not start well.

In the case of carburetor units, everything is quite simple - the engine itself starts very badly when hot. This is due to the fact that after stopping the car with a hot engine, the temperature in the carburetor area is quite high. Gasoline rapidly evaporates under the influence of temperature and fills all chambers and tubes of the carburetor in a gas state. But the float chamber remains empty. If you decide to start the engine within five minutes after stopping it, you will face the difficulty of starting because there is no liquid fuel in the chambers. Problems are solved by manual pumping or several attempts to start the power unit. However, there can be no such problem on injectors, since the fuel is supplied directly from the line. Therefore, it is worth looking for other troubles in the fuel supply system.

Too rich or poor mixture - air flow sensor

Above, we mentioned that problems with starting the car can happen due to the failure of the mass air flow sensor - the mass air flow sensor. This element of the car is one of the most delicate to the effects of the environment, therefore, its breakdown is often talked about. If it is very difficult to start the engine hot, check the operation of this mechanism. Also, this breakdown can be accompanied by the following factors:

• failures when pressing the gas pedal, lack of traction at some moments;
• decrease in power or vice versa - an inexplicable increase in the potential of the unit;
• complication of starting the engine and periodic moments of flooding;
• explosions inside the exhaust system when the gas pedal is pressed sharply;
• unstable revolutions due to periodic changes in mixture enrichment.

The fuel mixture of gasoline and air must have a certain consistency, which is formed by the mass air flow sensors and some other parts of the electrical and electronic system of your car. If these parts are faulty, you will have to change them and test the car, adjust the operation of new equipment.

Fuel pump overheated - a common problem of domestic cars

The fuel pump is naturally cooled by pumping cool liquid from the fuel tank. But in extreme heat, this liquid cannot be cool in any way, so the fuel pump overheats. This is an unpleasant incident that is fraught with the impossibility of starting the car hot. The car may simply stall on the road and not start either from the pusher or by starting by turning the ignition key. There are several ways to fix this problem:

• take a wet and cold rag, apply to the gas pump and periodically moisten it with cold water, cooling;
• open the hood and put the car in the shade, let all parts of the power unit cool down normally;
• change the fuel pump if you have the ability to quickly get another part of the fuel system;
• just wait until the temperature of the gas pump returns to normal and continue operating the car;
• an overheated fuel pump is unlikely to work normally, so it's better to just change it.

Such a problem can cause failure of important parts of the fuel pump, because when it overheats, it does not just stop working. If after cooling the car nothing changes, then you will have to replace the gas pump. But usually a cold car starts up, after which it still drives for several days without any problems.

Problems of poor starting of cars on gas in warm weather

Many drivers, after reading all the above arguments, will say that they are invalid for their car, since there is a gas installation. It became profitable to drive on gas several years ago, so HBO settled under the hood of many motorists. If in hot weather your car stalls and does not start on hot, you will have to let it cool completely, then start and go straight to the service station. It's best not to joke with this question for a number of reasons:

• due to the high temperature, certain seals could deteriorate and gas hoses could open;
• possible leakage of the working environment of the fuel system of your car for other reasons;
• the expansion of the gas in the tank at a high temperature creates a certain pressure in the system;
• it is better not to fill a full tank of gas in hot weather, limiting yourself to a partial refueling;
• it makes sense to consult with a specialist if such a problem begins to arise on your car.

It's not worth joking with gas cars at all - even the latest generation of HBO carries a certain danger. If your car on gas does not start hot, it is worth involving a specialist in solving this problem. So you can easily get the necessary features of the operation of the power unit, and also you will not expose yourself to the danger of incorrect operation of the fuel supply system. We suggest looking at the experts' explanations about a bad start during the hot season:

Summing up

High-quality fuel supply systems rarely fail, so even in the hottest weather, hot cars start up without problems. But in the event of such a nuisance, the driver is unlikely to be able to fix it on his own. There are too many factors of possible breakdowns that are difficult to check without special knowledge and certain tools. Therefore, it is best to show the car to specialists and get a very specific answer to your problem. Most likely, the repair of this problem will be associated with minor sensor replacements and not too expensive procedures.

Therefore, in most cases, it is the appeal to the masters that will be the key to a successful trip on your car in any weather. You need to contact the service station as soon as the manifestations of a poor start of the car began to appear in your case. The sooner you come to the master, the easier it will be for him to help you. And the cost of repairs increases when the visit to the master is delayed. Have you had a similar situation in the practice of driving a car?

Most modern cars are equipped with a fuel injection system. The system is installed only on gasoline engines. Despite the complexity of the design and high requirements for fuel quality, the injection engine has a number of advantages over the carburetor mechanism:

• automatic adjustment of the injection system depending on the load;
• quick start of the engine, increase in its dynamic performance;
• low emission of harmful substances;
• saving fuel consumption due to metered injection;
• does not need prolonged heating during low temperature conditions;
• the ability to program the electronic control system depending on the manner and driving style;

How the engine works

In principle, injection engines are similar to diesel engines: fuel is supplied through special nozzles. After the starter starts cranking the crankshaft, the control sensors send a signal to the electronic control unit, which indicate in which stroke the cylinders are located.

After reading the data, the control unit sends a signal to the injector of the cylinder, which is in the intake stroke. The nozzle opens for a strictly defined time, which corresponds to the readings of the mass air flow sensor.

Table of values \u200b\u200bof mass air flow sensor.

After the end of the intake stroke, compression occurs. The central module receives data from the DPKF and DF sensors that the piston is at top dead center. After processing the data, the signal is sent to the ignition unit, which transfers voltage to the desired cylinder. The task of supplying voltage correctly is provided by two transistors located in the control unit housing.

Further, when the ignition of the working mixture occurred, the cylinder began to operate in the combustion chamber, the ECU takes readings from the knock sensor and adjusts the ignition angle for the next cylinder.

For more efficient use of fuel energy, an oxygen sensor is installed in the exhaust system. Using the indicators received from the sensor, the control unit adjusts the composition of the mixture, sets the opening time of the nozzle. If there is a lack of oxygen when the throttle is open, the ECU opens the idle speed controller.

Reasons for improper operation of the injection engine

There may be several reasons why the injection engine does not start well when cold. The main one is sensor malfunction.... If one of the modules breaks down, the electronic control unit receives incorrect data, from which the engine starts poorly and runs intermittently.

Common causes of poor starting of an injection engine.

Air leaks

It occurs when there is a leak in the parts of the air supply system. The mass flow sensor is unable to capture some of the air entering the engine, which is why a lean mixture is supplied to the combustion chamber. This leads to erratic idling and the problem of cold start of the injection engine.

During warm-up or suction operation, this problem is almost invisible, but when the engine warms up to operating temperature, idling interruptions become more noticeable.

Air leaks can occur for the following reasons:

• violations of the tight connection in the vacuum amplifier;
• mechanical damage to the fasteners and the air supply hose to the intake manifold, pipelines of the pressure regulator and the crankcase ventilation system;
• damage to the gaskets between the cylinder block and the intake manifold.

The cause of air leakage can be determined by visual inspection. If a malfunction significantly affects idle operation and starting a cold injection engine, before repairing, you can increase the speed by disconnecting the plug from the mass flow sensor. This action will lead to a significant increase in fuel consumption, therefore it is not recommended to delay the repair.

In case of slight suction, it is enough to adjust the fuel supply using the L-probe device.

Main indicators of the fuel and air mixture

Mass flow sensor malfunction

Incorrect operation or breakdown of the sensor leads to an immediate stop of the motor after starting. When this happens, you must disconnect the sensor and restart the car. If the engine runs smoothly, then the flow sensor needs to be replaced.

Temperature sensor defective

When the central control unit receives no signals from the coolant temperature module, it assumes a zero value. The built-in program prepares the working mixture according to this temperature, which leads to the following consequences:

• the injector engine does not start well when cold;
• detonation at low speeds.

The module is not repaired, so the defective part is replaced with a new one.

Defective ignition

The problem can be corrected by setting the moment of spark supply, adjusting the position of the timing belt and replacing damaged parts.

Table of resistance indicators of the temperature sensor from the temperature of the cooling medium.

A breakdown in the fuel regulator leads to leakage of fuel into the combustion chamber through the intake manifold pipes. As a result, a rich mixture enters the engine, which leads to severe plugging of the spark plugs. This malfunction significantly affects the cold start of the injection type engine.

Camshaft phase sensor

The breakdown leads to the transition of the fuel supply mechanism in emergency mode, in which the injector delivers fuel twice as much as necessary.

Reasons for replacing the module:

• difficult start;
• interruptions in the vehicle self-diagnosis system;
• significant increase in fuel consumption;
• smoke in the exhaust mechanism.
• difficult cold start of the injection engine

You can fix the problem by self-adjusting the position of the sensor or contact the service center.

Stepper motor.A malfunction of this element does not allow maintaining idle speed (the engine does not have enough air). Driving the vehicle is possible if the throttle pedal is idling when the load is removed. If you have a DST-2M or DST-8 tester, set the idle speed on a warm engine at 900 - 1000 rpm using a stepper motor (if it is still controlled). Remove the connector from the stepper motor.

In this state, you can safely drive a car without experiencing difficulties if the temperature outside is up to - 5˚. In cold weather down to -15˚, starting a cold engine will be difficult, but using the same throttle pedal, you can warm up the engine (using the pedal like a suction in a carburetor). After -18˚, starting the engine will become problematic - it will be difficult to ensure the specified air flow rate when the system changes from starting mode to warming up mode. The engine will stall, and after 2 or 3 such attempts, the candles will flood.

Air leaks.A leak in the air intake system downstream of the mass flow sensor causes instability at idle. The mass flow sensor “does not see” a part of the air entering the engine, so the system incorrectly calculates the fuel supply (too little fuel - lean mixture). On a cold engine and a slight suction, this effect may not be noticed, but as it warms up, the instability of idling becomes more and more obvious and can lead to engine stalling. The reasons for the suction can be:

Break (violation of fasteners) of any of the hoses that have an outlet to the intake manifold (from a small tube to a pressure regulator to large crankcase ventilation tubes);

Violation of the tightness of the vacuum amplifier;

Damage to the gasket between the intake manifold and the engine, etc. Basically, the reasons for air leaks can be determined visually. If an air leak makes it impossible for the engine to idle, remove the connector from the MAF sensor. In this case, the idle speed will increase, but it will be possible to reach the destination by car. If, at the same time, the stepper motor is still set in the position of an acceptable idle speed, then the inconvenience of control when the car is moving will be less. A small leak in the air supply system may not lead to noticeable changes in the driveability of a car equipped with systems with fuel supply control using an L-probe sensor, but the engine efficiency will drop.

Faulty mass flow sensor.This defect causes the vehicle to stall after starting. If the engine stalls after starting and you are not sure what is wrong, try starting the engine with the mass flow sensor connector removed. If the engine is running after this, then there is a high probability that the sensor is out of order.

Temperature sensor defective.The engine will not start at temperatures below -8 ° C. In warm weather, it is possible to maintain idle speed after starting by slightly depressing the throttle pedal. In the standby mode of the system, if the temperature sensor fails, the coolant temperature is set based on the engine running time. Starting a hot engine in the event of a temperature sensor failure will have its own challenges.

Defective throttle assembly... A hot engine stalls after starting - there is no transition to idle. Pressing the throttle valve immediately after starting the engine helps. You can bend the closed throttle position limiter tab, but so that the throttle position sensor reads 0 when the pedal is released (checked by the tester).

Defective ignition... There are no recipes here, except how to replace all faulty elements of the ignition system.

Defective fuel regulator... The fuel regulator leaks, additional fuel enters the intake manifold through the air pipe, the engine fills. In this situation, you should remove the pipe from the intake manifold, the engine should run stably.

In this article, we will try to find out: why the car does not start cold, hot, or just stalls after it heats up. What needs to be done to fix these problems, as well as discuss other options for engine malfunction.

Cold engine won't start

As a rule, such a nuisance arises in the winter, when you do not expect any troubles from your car at all.

The most common reason is the battery. Many car owners know that batteries cannot be repaired, and their service life is limited, but hardly anyone will think about this until the spent battery makes itself felt. This happens most often in cold weather.

But the reason why the engine does not start on a cold one may be other reasons:

• the fuel pump is worn out, and for this reason is not able to create the necessary pressure in the fuel system to start the engine on a cold one;
• the filter for cleaning the air mixture is so dirty that it does not pass the required volume of air well;
• poor quality fuel that can clog the vehicle's fuel system. You should not pour everything into the tank;
• the reason may be the carburetor, which has stopped working properly the throttle or the idle valve has failed;
• hypothermia of the engine in frosty weather.

In order to ensure free engine start in cold weather, experts recommend adhering to the following rules:

• maintain all electrical circuits in good condition;
• the rechargeable battery must be in good working order, charged, and have the appropriate capacity;
• refuel with fuel appropriate for the season at proven gas stations that have fuel quality certificates;
• there must always be a certain level of fuel in the tank;
• the ideal option is to keep the car in a warm garage;
• the engine must have the "correct" oil for the season;
• there should be a cable in the trunk of the car, it is desirable to have cables for starting the engine from a battery - a donor, so that at the right time you can "light up from a neighbor";
• equip the car with an autostart system.

Hot engine won't start?

Another common problem, and the happy owners of domestic models know about it firsthand - the car does not start up hot. Much has already been said about the poor performance of the fuel pump on VAZ models. This happens especially often in extreme heat and with long standing in traffic jams.

But the owners of cars with diesel and injection gasoline engines may also encounter trouble when the car does not start. The reasons why the engine does not start well are just as varied:

1. From the sensor, which monitors the temperature of the coolant, distorted information is received, which leads to an incorrect supply of the combustible mixture.
2. The tightness of the fuel injectors is broken, as a result of which the fuel mixture is re-enriched and the engine will not start.
3. In diesel engines, the injection pump (high pressure fuel pump) does not work correctly. It is worth considering replacing the plunger pair or bushings.
4. It is recommended to check the operation of the crankshaft position and air flow sensors.
5. Check the idle speed and fuel line pressure regulators.
6. Bad condition of the armored wires.
7. Incorrect operation of the ignition module.

Hot motor stalls

The car started up, it works normally, but as soon as the sensor detects the operating temperature, the engine stalls when heated. Of course, this is bad and incomprehensible.

Here are some reasons for this strange behavior of the motor, as well as ways to solve the problem:

1. The car worked fine, but as soon as we drove away from the gas station and it began to twitch when the gas pedal was pressed, the engine stalls or does not start well. Everything is simple - low-quality fuel. Drain the defective fuel, purge the fuel system, replace the fuel filter. In addition, the spark plugs should be replaced (by the way, this is another strong argument in favor of always taking a check at the gas station, then there will be someone to present a claim to).
2. The fuel is normal, the car used to work, but it stopped running on a hot engine, it stalls - it's time to replace the fuel filter.
3. The same can happen if the air filter is clogged - the engine simply has nothing to "breathe" with when heated, the air mixture is re-enriched with fuel and the engine stalls. Change the air filter.
4. Returning to the gasoline pump - a typical picture for VAZ engines: the engine stalls when hot. It can be repaired, but it is better to replace it with a new one.
5. The generator has stopped charging the battery. In the best case, you can do with tightening the alternator drive belt. Did not help? This means the generator is out of order. But with such a breakdown, it will not be possible to start the car again - the battery will be discharged.

Conclusion

On modern cars, numerous sensors are responsible for the correct operation of the engine in any weather. And if you do not know where they are, then it’s time to contact the specialists at the service center.

“I have a bad start when it is cold,” - such complaints can be heard from men in cold weather, when discussing cars. This may describe different symptoms and behaviors, but the problems that cause a car to start badly when cold are usually almost the same. The difference in the reasons for a difficult start can only be depending on the type of engine; since gasoline (injector or carburetor) have their own reasons, and diesel, of course, will have others. In this article, we will consider the most common cases of such problems as:

The reasons why it is bad to start on a cold

It is important to distinguish between situations in which problems arise: the car does not start well after idle time, when it cools down, (especially in the morning) if it refuses. They all have their own nuances and reasons that worth considering separately.

We will figure out in general terms what reasons lead to a poor start of a cold engine. Usually one or two rotations of the starter armature shaft are enough to start a car in good condition. If this cannot be done, you need to look for why.

Main reasons:

In addition to these cases, there may be others, less common, but equally significant. We will also mention them below.

On gasoline engines an indicator that it starts badly and dulls on a cold, can become candle... We unscrew, look: flooded - overflows, we look further point by point; dry -, we also sort out the options. This method of analysis will allow you to start finding out with simpler ones and gradually approach more complex reasons for a poor engine start on a cold one, and not look for them in the fuel pump, disassemble the injector, climb to the timing mechanism, open the cylinder block, etc.

But diesel engine the first in the list of faults will be weak compression... So the owners of diesel cars should pay special attention to it. In second place is fuel quality or its inconsistency with the season, and in the third - glow plugs.

1. Keep the tank full - this will prevent condensation from forming and water will not enter the fuel.
2. Turn on the high beam for a couple of seconds before starting - it will restore part of the battery capacity on frosty days.
3. After turning the key in the ignition lock (on an injection car), wait a few seconds until normal pressure in the fuel system is created, and only then start the engine.
4. Pump up gasoline manually (on a carburetor car), but you need not overdo it, otherwise the candles will flood.
5. Cars running on gas, in no case should you start a cold one, first switch to gasoline!

The injector starts poorly on a cold

The first thing you should pay attention to in case of poor operation of an injection car are sensors. Failure of some of them leads to difficult starting of the engine, since incorrect signals are sent to the ECU unit. Usually it is difficult to start on a cold due to:

• coolant temperature sensor, DTOZH informs the control unit about the state of the coolant, the indicator data affect the engine start (unlike a carburetor car), adjusting the composition of the working mixture;
• throttle sensor;
• fuel consumption sensor;
• Mass air flow sensor (or MAP, intake manifold pressure sensor).

There is often a problem with cold start. Well, of course, whether it be an injector or a carburetor, when a cold car does not start well, if it troit, rpm jump, and after warming up everything is fine, it means that the condition of the candles is checked without fail, and we check the coils and BB wires with a multimeter.

Deliver a lot of trouble permeable nozzleswhen it is hot outside, the car will not start well on a hot engine, and in the cold season, the dripping injector will cause a hard start in the morning... To test this theory, it is enough to simply bleed the pressure from the vehicle in the evening so that there is nothing to drip, and in the morning to look at the result.

It is impossible to exclude such a banal problem as in the power supply system - it complicates starting a cold motor. Also pay attention to the fuel poured into the tank, as its quality greatly affects the start of the engine.

On cars such as the Audi 80 (with a mechanical injector), first of all we check the starting nozzle.

General advice: if the starter turns normally, the candles and wires are in order, then you need to look for the cause of the poor start of a cold engine by checking the coolant sensor and checking the pressure in the fuel system (which one holds and for how long), since these are the two most common problems.

The carburetor does not start well when cold

Most of the reasons that the engine with a carburetor does not start well, or does not start at all, are associated with malfunctions of such elements of the ignition system as: spark plugs, explosive wires, coil or battery. therefore the first thing to do - unscrew the candles - if they are wet, then the electrician is guilty.

Quite often, in carburetor engines, difficulties arise with starting when the carb jets are clogged.

The main reasons why it won't start cold carburetor:

1. Ignition coil.
2. Switch.
3. Trambler (cover or slider).
4. Incorrectly adjusted carburetor.
5. The diaphragm of the starting device or the diaphragm of the gasoline pump is damaged.

Of course, if you pump up gasoline before starting and pull out the suction more, then it starts better, but all these tips are relevant when the carburetor is correctly configured and there are no problems with the switch or candles.

If a car with a carburetor, be it "Solex" or "DAAZ" (VAZ 2109, VAZ 2107), starts up on a cold one, and then immediately stalls, filling with candles - this indicates a malfunction of the diaphragm of the starting device.

Advice from the experienced car owner VAZ 2110: “When the engine does not start on a cold engine, you need to smoothly press the gas pedal all the way, turn the starter and release the pedal back as soon as it grabs, keep the gas in the same position until warming up”.

Consider some typical caseswhen it does not start on a cold:

• when the starter turns, but does not grab, it means either there is no ignition on the spark plugs, or gasoline is also not supplied;
• if it grasps, but does not start - most likely, the ignition is knocked down or, again, gasoline;
• if the starter does not turn at all, then the battery is probably dead or something connected with it.

Why is it difficult to start a cold carburetor

If everything is normal with oil, candles and wires, then perhaps there is a late ignition or the starting valve in the carburetor is not adjusted. However, there may be a torn diaphragm in the cold start systemand the valve adjustment also says a lot.

To quickly find the cause of a poor cold start engine with a carburetor power system experts recommend checking first: spark plugs, high-voltage wires, carburetor starting device, idle jet, and only then also inspect the breaker contacts, ignition timing, fuel pump operation and the condition of the vacuum amplifier tubes.

Starts poorly on cold diesel

As you know, the start of a diesel engine occurs due to temperature and compression, therefore, if there are no problems in the operation of the battery and starter, there can be 3 main ways to find the reason why the diesel engine does not start well in the cold in the morning:

1. Insufficient compression.
2. No candle glow.
3. Missing or fuel supply interrupted.

One of the reasons that a diesel engine does not start on a cold engine in particular, and a poor start of a diesel engine in general, is bad compression... If it doesn't start in the morning, but grasps it from the pusher, and then for a certain time there is a gray smoke, then this is 90% low compression.

The blue smoke of the diesel exhaust at the moment of rotation by the starter means that the fuel is supplied to the cylinders, but the mixture does not ignite.

An equally common case when the owner of a car with a diesel engine cannot start a cold engine, and a hot one starts without problems - if no glow on candles... The glow plugs heat the diesel fuel until the diesel reaches the operating temperature.

Options, why don't the candles workmaybe three:

• the candles themselves are faulty;
• the case in the relay of candles. Its operation is regulated by the indicators of the coolant temperature sensor. During normal operation, the relay emits quiet clicks when the key is turned in the ignition lock before starting, and if they are not heard, then you should find it in the block and check;
• oxidation of the glow plug connector. It is not worth explaining how oxides affect contact.

3 ways to check glow plugs

A car is a rather complex mechanism, in which there are various units responsible for certain functions. Most owners are often faced with the fact that their car does not start well when cold. This problem is especially common for old foreign cars and old domestic cars. There is no definite solution to this problem. We propose to consider the main reasons that are associated with the fact that the car does not start on a cold one.

Poor quality fuel.

It so happens that even at gas stations of well-known brands, you can fill in poor-quality fuel, and then bite your elbows, because the car does not start or does not start, but with difficulty. It is very difficult to determine this probability, because when you leave the gas station, the car is still running on the old fuel, and will work until the new fuel enters all the fuel channels of the car.

The main types of low-quality fuel:

1. Contaminated fuel is fuel in which various deposits are present. They contaminate the fuel channels, wires and filters. As a result, the gasoline pressure drops and the car will not start.
2. Low octane. As a rule, on such fuel, the car starts up on a cold one from the second or even the third time, you can hear the engine running noisily, traction disappears, and detonation occurs. It is highly discouraged to start a car on such fuel; it is better to drain it right away and fill it with high-quality fuel.

Fuel pump malfunction

Another reason why the car does not start well when cold is a malfunction of the fuel pump.

In order to check whether the fuel pump is working, you need to turn on the ignition, while a buzzing will be heard from the side of the gas tank, it will last for several seconds. As soon as the fuel supply stops, the correct amount is pumped up and pressure builds up in the fuel rail. The pump will then automatically shut off.

If, you do not hear buzzing, and the car does not start, then you need to check the serviceability of the fuel pump.

Fuel filters are installed on modern cars. They filter fuel from various unnecessary deposits or sand, of which there is a lot.

If the fuel filter becomes clogged, then the required pressure is not created in the rail, and the car becomes very difficult to start. The mixture in this case begins to be supplied to the engine lean. Since the temperature in the cylinders is low, it is extremely difficult to ignite such a mixture. Hence the problem with cold starting the engine.

Leakage of the air supply system.

As you know, an internal combustion engine does not run on clean fuel, but on a mixture of fuel and air. If the engine does not have enough air, then the mixture begins to richer, which does not bode well either.

With a rich mixture, misfires will appear, since in order for the combustion to take place fully oxygen is needed, which is contained in the air.

On older cars, it is very likely that the spark plugs will be flooded, as the fuel mixture will flow into the cylinders, even though it does not ignite, and will fly out into the exhaust manifold without igniting.

On new cars, the system automatically turns off the cylinder nozzle, where ignition does not occur, and the check lights up.

Dirty choke

Oddly enough, a dirty throttle valve can also cause the car to start poorly on a cold one. As you know, the throttle valve serves to regulate the air supply to the engine.

If the throttle valve is clogged, then not clean air begins to enter the engine, but air in which various oil deposits, dust particles and other unnecessary substances are present, they prevent the formation of the correct mixture of the desired consistency.

Also, the throttle valve can easily jam, due to the excess deposits formed in it.

Malfunction of the ignition system.

Another common option that makes a cold engine hard to start is a malfunction of the ignition system.

Very often, due to temperature differences, microcracks appear in the ignition coils. As we know, when the body is hot it expands. In our case, the distance between the walls of the crack becomes minimal and the microcrack does not give a breakdown, but to a cold one, the bodies return to their original state, the microcrack increases in size, and gives a breakdown to the engine housing or body. The spark does not reach the spark plug, the mixture in the cylinder does not ignite, the car does not start well.

This problem is inherent not only in ignition coils, but also in any other elements that are involved in this process - distributor, armored wires and even candles.

Weak battery power.

Let's say you arrived in the evening, parked your car, and went home. In the morning, you try to start the car, but the car won't start. The starter does not turn, the instrument panel blinks - the output is dead.

If an old battery is installed on the car, then everything is clear, it needs to be changed and the problem will go away. But it so happens that the battery is normal, and the capacity holds well. In this case, you need to look for a leak in the car wiring. In car stores, a special device is sold that allows you to determine if there is a leak in the car, in calm mode. Perhaps any electronic device is defective and drains the battery. Either a non-standard radio is connected incorrectly, or just some wire has become unusable and gives a short circuit to ground (especially important for old cars).

Let's say the leak test did not give any results, and there are no leaks, then it makes sense to check the charging from the generator. If it is insufficient, the generator will not fully charge the battery. And since it is more difficult for a starter to turn a cold engine than a hot one, it will start with problems unambiguously.

Idle sensor malfunction

The most common cause of cold start problems is a malfunctioning idle speed sensor.

The idle sensor is an electromagnet with a rod. It is controlled by the vehicle's ECU. When the car is cold, the engine temperature sensor signals this to the ECU and the ECU, in turn, sends a signal to the idle speed sensor. The idle speed sensor stem extends, opening the throttle valve slightly. This increases the engine speed when it is not warmed up. When the engine warms up, the ECU sends a signal to this sensor, and pushes the rod back, while the speed decreases, the engine starts to work at its normal operating temperature.

When the idle speed sensor is faulty, it does not extend the stem and does not slightly open the throttle valve, or it does not fully. Most often this happens due to contamination or failure of the coil, which is located inside this sensor.

The reasons for poor engine start include low compression in the cylinders. The car does not start well when it is cold. This is true for both gasoline and diesel engines.

As a rule, many other factors signal a low engine compression.

Why does the car start badly when cold at low compression? - the answer is simple. Thermal expansion of metals. When the insides of the engine are warmed up, they expand in volume, albeit slightly, but this is enough for the compression to rise a little and the engine starts. On a cold one, there is no expansion, and since the compression is low, we conclude that there will be a bad start of a cold engine.

In winter, many owners try to change the oil on their car. But few know that in winter it is better to use oil that is suitable for a car, but with a minimum viscosity, since too thick oil solidifies in cold weather, and it is very difficult to drive it through the oil channels with a cold engine. And if there is also an old battery that does not hold capacity, then this further exacerbates the situation. This item is relevant for both diesel engines and gasoline engines.

Carburetor engine will not start cold.

As you know, the carburetor is a system of mechanical fuel injection into the engine. It is very primitive, and unlike the injector, it does not have such a large number of sensors that simplify the use of the car.

As a rule, there is a suction in the carburetor, which opens an additional chamber for air supply, thereby increasing the speed. If the suction is not working properly, then it is very difficult to start the car on a cold one, since the standard speed of a cold engine is not enough for its normal operation when it is not warmed up.

Why does the diesel not start on a cold

Diesel fuel can freeze at low temperatures. Therefore, this type of fuel has varieties for each season. Summer diesel fuel is poured in in summer, winter diesel fuel is poured in in winter, but in regions where it is very cold, "arctic" is poured.

It so happens that the wrong fuel was filled by mistake. The air temperature went into minus and it froze. Of course, the pump cannot pump the frozen diesel fuel, so the engine will not start.

Sometimes, at low-quality gas stations, water can get into diesel fuel. After filling with such fuel, it settles at the bottom of the tank, and can also freeze in the fuel lines or in the filter.

Difficulty starting the engine on cold can manifest itself in various conditions. In the first case, the car has difficulty starting after a long idle period, for example, after an overnight stay. In the second case, starting is very difficult after the engine has been warmed up to operating temperatures, then the engine has cooled down and starts poorly when you try to start it again.

In addition, it is worth noting that any problems with starting the engine may be completely absent "hot". It is also worth considering the outside air temperature, especially if the car does not start in winter.

Read in this article

The main reasons for a bad start

The list of reasons why a cold engine does not start well is quite wide. Before starting diagnostics, it is necessary to more accurately localize the malfunction. Make sure that it is charged, the starter turns the engine smoothly (at the same speed). Additionally, it is worth excluding the possibility of refueling with low-grade gasoline.

Fuel supply

Problems with starting the engine can arise as a result of the lack of fuel supply, and due to failures in the process of its ignition in the engine cylinders. In terms of fuel delivery, the fuel may be too low to start. It is also possible that the spark plugs are flooded with excess fuel.

1. It is worth starting the check to make sure there is an exhaust. If a slight smoke appears from the exhaust pipe after turning the starter motor, then this indicates that fuel supply to the cylinders is present.
2. The next step is to unscrew the spark plugs. The spark plugs must be unscrewed after an unsuccessful attempt to start the engine. If the spark plug is filled with gasoline, then this can often indicate problems with the tightness of the injectors or ignition. Check the integrity of the spark plugs themselves and high voltage wires, and also make sure there is a spark on the spark plugs. A dry spark plug will indicate that no fuel is being supplied to the cylinder.
3. Clogged coarse and fine filters, as well as faulty or heavily coked filters, can also interfere with the normal supply of fuel to the engine. Fuel may also not flow to the engine due to the fact that a sudden has occurred. This means that the fuel pump is not generating the required pressure. To find out the reasons, you will need to check the fuel pressure in the rail and the gas pump itself.

An additional nuance may be air leakage in the fuel system. Inspect the lines for damage, bends, cracks, etc. Leakage of gasoline is a clear sign of loss of tightness in the fuel lines.

Electronic sensors

The electronic injection system is equipped with special sensors, thanks to which interaction with the engine is realized. Failure of individual electronic components can lead to incorrect signals being sent to the control unit and the engine cannot be started.

If the engine does not start, then several sensors need to be checked:

• (DPRV);
• throttle position sensor (DPDZ);
• (DMRV);

It is also necessary to clean the throttle in parallel, check the air filter and valve XX. Self-diagnosis of sensors can be carried out using a multimeter.

Ignition check

The engine may not start if the ignition distributor is faulty. This malfunction manifests itself in such a way that when the starter rotates, the so-called seizure does not occur, that is, there are no signs of single attempts to ignite the fuel-air mixture in the engine cylinders.

It is also worth paying attention to the belt and its drive. In some cases, it is worth checking the state of the variable valve timing system (if any). The ignition coil can be checked with a multimeter.

Reducing compression

Loss of compression in one or more engine cylinders is a consequence of natural wear or damage to the power unit. The engine with low compression will not start "cold", as there is a strong increase in the gaps between the parts in the cylinder. In other words, it is not possible to achieve the required pressure in the combustion chamber to ignite the working mixture at the moment of start-up.

Common causes of this malfunction may be piston destruction, breakage or sticking of piston rings, timing burnout, wear of cylinder walls, etc. Low compression is more often manifested during a cold start, but it can also be present all the time (when trying to start a badly worn engine "hot"). An engine with such a malfunction is most difficult to start in low temperatures. Compression must be measured for accurate diagnosis.

Read also

Why does the starter turn normally, but the engine does not pick up, does not start. The main causes of the malfunction, checking the fuel supply systems, ignition. Tips.