The engine does not start well: causes and solution to the problem

There are many reasons for this. But among them we can distinguish those that occur in almost 90% of cases.

First of all, it is necessary to exclude the influence of low temperatures. In cold weather, the car may not start due to insufficient battery power, as well as due to the use of summer oil, which becomes very thick (these are two main reasons, but there may be others: for example, bad spark plugs or a clogged fuel pump).

Installing an automatic engine warm-up system can help here. If problems with operation occur even at positive temperatures, then it is necessary to continue troubleshooting.

1. Quite often, poor car starting is due to low fuel quality. In this case, the injectors and fuel filters may become clogged.
2. The air filter may also become dirty. Replacing it is quite simple and completely solves the problem.
3. On diesel engines, poor starting can be caused by incorrectly selected fuel. Such motors require a seasonal change in types of diesel fuel (“summer”, as well as “winter” or “arctic” - for especially cold regions).
4. Low compression in the combustion chamber. A decrease in pressure can occur due to engine wear (during its operation, the gaps are closed by an oil film, while when they cool, they reappear), as well as due to incorrect installation of the timing belt.
5. Another reason why an injection engine has difficulty starting when cold is the failure of the sensors (DPRV, DPS, DMRV).
6. It was already written above that problems with starting in winter can arise due to bad spark plugs or a clogged fuel pump. It is worth noting that these problems can also arise at positive temperatures.
7. Sometimes poor starting is caused by a lack or, on the contrary, an excess of fuel when supplied. On injection engines, spark plugs may flood in the winter (this problem usually occurs in used cars). In this case, you need to unscrew them and dry them.
8. A fairly common reason why a cold engine does not start well is contamination of the throttle valve. In this case, it does not open completely, which is why the motor does not work properly.
9. There is a fault in the electrical circuit. If the battery has a charge, but there is no spark at the spark plugs, you need to make sure that the high-voltage wires are intact, as well as the functionality of the ignition coil (checked with a multimeter). True, with such a breakdown, starting problems will arise not only on a cold engine.
10. Sometimes the cause of poor starting is a dirty idle air valve. After cleaning it, problems with engine operation should disappear.

Important! If, when you try to start the engine, smoke comes out of the exhaust pipe and the car does not start, it means that fuel is being supplied, but it is not ignited.

Identifying and eliminating engine starting problems

In most cases, problems can be identified and fixed without much difficulty. So, a sign of clogged fuel filters will be difficulties starting the engine (it may stall at idle), a decrease in power, and also the car jerking during inclines.

It is worth noting that such “symptoms” can also be the result of other faults, such as wiring problems or faulty spark plugs. In this case, it is necessary to urgently replace the filters. If this is not done in time, the motor may fail.

Fuel supply can be checked by unscrewing the spark plugs. If they are filled with gasoline, or, on the contrary, are completely dry, then it is necessary to check the sensors or adjust the carburetor.

Another problem, a sign of which may be that the engine does not start when cold, is clogged injectors. In this case, the car loses dynamics when accelerating sharply, twitches and reacts poorly to pressing the gas pedal. In addition, muffled high-frequency noises may be heard coming from the cylinder block.

If the injectors are indeed coated with deposits, they need to be cleaned. You can do this yourself. There are several main ways to restore this part:

1. The first cleaning method is rather preventive. It consists of adding special additives to the fuel that help get rid of deposits on the injector. However, many motorists try to use this method as little as possible: it is believed that additives can further worsen engine performance.
2. Some experts recommend periodically turning the engine up to high speeds. After several kilometers at a speed of 100-110 km/h, engine performance should improve somewhat.
3. If the injectors are seriously dirty, you will have to clean them manually. To do this, you need to disassemble the injector. After this, the parts are washed with high-quality fuel without impurities or kerosene and blown with compressed air.
4. There are two more ways to clean injectors. They guarantee almost 100% results, but to implement them you need to use professional equipment and have certain skills. Therefore, it is better to contact a service center here. In the first case, the parts are exposed to ultrasound, which destroys all plaque. In the second, a special liquid and a device are used that is connected to the fuel receiver. After the engine has been idling for some time, the injector will be cleaned.

Important! You should not take action without making sure that a specific node is indeed the cause of the poor startup. This is especially true for complex work, the incorrect execution of which can lead to even more serious damage. If in doubt, it is better to turn to professionals.

In conclusion, it is worth adding that it is better to look for the reasons for poor starting of a cold engine as they become more complex. So, you should not check the timing belt or engine compression without making sure there is fuel in the gas tank and a charge in the battery.

By methodically considering all possible fault options, you can get to the true cause of a poor start, and, in most cases, fix it yourself.

What to do to fix the problem

As we have already seen, the problem of floating speed can be hidden in different places. Therefore, if you notice unstable engine operation, you need to seek diagnostics in time. Experienced DDCAR specialists will help determine the cause of the malfunction and eliminate it as soon as possible.

Engine diagnostics

Correct diagnosis is 90% of success in solving a problem. You should not spend money prematurely on purchasing sensors and other parts in the hope that after replacing them the problem will go away. There's a good chance it will be wasted effort. Listen to your car, have it serviced at trusted service stations and contact experienced diagnosticians!

Why does my car start poorly when cold? List of reasons

Why is my car hard to start when cold? This question can often arise among drivers and car owners who just recently drove the car, and everything was fine, it sat, cooled down and does not start or starts with great difficulty.

It should be noted that there are no problems when it’s hot. Many modern cars have heating systems installed before starting, however, this does not always save.

When such problems arise, and often this happens in the morning, in front of the car with the hood open, fuss begins to warm it up and subsequent frantic attempts to start it. But, probably, every person who has a car wants to get into it, start it and drive, and not wake up with thoughts of whether it will start or not. In this article we will look into what causes the power unit to start poorly when cold.

Why is it difficult to start a car when it’s cold? It is impossible to answer this question unambiguously and accurately. The following can be taken as the main axioms of the reasons: there is nothing to ignite in the combustion chamber and there is nothing to ignite in the combustion chamber.

Of these two principles, all the rest will be only causes of a given effect. So, now let's look at each axiom separately. The concept of nothing to ignite means not only the absence of fuel, but also poor quality of its supply to the combustion chamber: too little fuel and too much fuel.

An indicator of the first reason can be a candle. We unscrew it (after turning it with the starter) from the engine and look at it: if it is flooded with gasoline, it means it is overflowing and we look further point by point, if it is dry, fuel is not delivered and again we look for the reason point by point. Also check the candle by smell - if it doesn’t smell like gasoline at all, then the cause has been found.

Let's move on to the second reason. If we checked the fuel supply and everything is as it should be, we look for the cause in the ignition device:

• First of all, we check the battery. It may be too discharged, and the starter barely turns or at different speeds;
• Malfunctions in the ignition distributor. At the same time, the machine does not try to “grab”, so to speak;
• Fracture or piercing of a high-voltage wire. In a shaded area when starting the engine, you can see a glow on these wires;
• The ignition coil is faulty. You can check with a multimeter (if there is only one ignition coil);
• The simplest thing is that the spark plugs have failed.

Naturally, when first considering the problem of cold starting, you should not look for the problem in the fuel pump, disassemble the injector, go to the timing belt, or open the cylinder block. As a rule, such reasons are rare, but they do occur, so you still need to start with the simpler ones and gradually move closer to the more complex ones.

In the article we tried to answer the question as fully as possible: why is it difficult for a car to start when it’s cold? If these problems occur, try leaving the car in cold air less often or warm it up over time.

Today you can find special devices that will maintain the engine temperature constant or turn on and warm it up at certain intervals. For example, the Tomahawk copes with this task.

About DTOZH

In general, power unit temperature sensors are the most important regulators of an injection engine. There are two of them on it. One is located directly in the cylinder head, it displays the temperature value on the instrument panel.

The second one is located in the thermostat, and provides data on the temperature of the control unit of the power unit. Based on the results obtained, the control unit regulates the fuel supply - it supplies more fuel to a cold internal combustion engine, and less to a hot one. In addition, it is the control unit that regulates the OZ, influences the ignition of the fuel assembly, and activates the coolant fan if the liquid temperature rises above 100 °C.

Obviously, with faulty DTOZh there will be difficulties in the operation of the motor. However, this applies more to the DTOZH, which provides information directly to the block. For example, if the DTOZH is faulty, it will give false values ​​about a cold engine, although it is already boiling.

The supply of fuel to the cylinders will increase, because this is provided by the system. Let's say you drove for a long time, then stopped and went into a store. Now starting the power unit will cause obvious displeasure, since it will take a very long time to start due to data failures and oversaturation.

Why does the injector take a long time to start due to DTOZhO At the same time, the OZ, which is responsible for the ignition of the fuel assembly, which is clearly over-enriched, changes greatly. As a result, the fuel will evaporate intensively, and the concentration of gasoline in the fuel assembly will be so high that the mixture will hardly ignite due to the small amount of oxygen.

It was said above that when you press the accelerator pedal, the startup time will be noticeably reduced. Now it becomes clear why this happens. By pressing the gas, we add oxygen to the fuel assembly, and the fuel ignites faster.

Thus, by replacing a faulty DTOZh, you can solve not only the problem with long-term starting of the internal combustion engine, but also other difficulties relating to the process of engine operation and its cooling system. The engine, after replacing the faulty DTOZH, will add stability, throttle response and power.

For what reasons can a car have difficulty starting when cold?

It happens that you urgently need to go to work, but the car, after sitting all night, will not start. So why does a vehicle that is in good working order after the last trip suddenly refuse to start? Or does it stall as soon as you crank the engine? Let's look at the reasons why a car may have difficulty starting when cold.

First of all, it is necessary to make a reservation - your car starts perfectly if the engine has not had time to cool down, but in the case when the vehicle sits until the engine has completely cooled down, starting is difficult or completely impossible. In such a situation, even modern systems for heating and maintaining engine temperature do not always help. Let us consider in more detail the situation when a cold engine does not start well.

The air supply system is not tight.

As you know, an internal combustion engine does not run on pure fuel, but rather on a mixture of fuel and air. If the engine does not have enough air, the mixture begins to get rich, which also does not bode well.

With an enriched mixture, misfires will occur, since in order for combustion to fully occur, the oxygen contained in the air is necessary.

On older cars, there is a high probability of flooding the spark plugs, since the fuel mixture will enter 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 injector where ignition does not occur, and the check light comes on.

Causes of problematic startup

Causes of problematic starting of a cold engine

When determining the reasons why the car has trouble starting when cold, you will first need to make sure that the battery is not discharged and that the starter is in good working order (the engine turns smoothly and smoothly). A separate reason that requires exclusion is refueling a car with low-grade gasoline. The quality of the fuel being poured greatly influences the trouble-free starting of the vehicle. If the battery is not discharged, the starter is working properly and the fuel is of appropriate quality, you can suspect the following main problems if it is difficult to start the vehicle when it is cold:

• the fuel pump has failed;
• the fuel filter is clogged (due to low-quality fuel);
• injectors are clogged (due to fuel);
• The fuel pressure regulator has malfunctioned;
• air leak;
• the spark plugs, ignition coils, and high-voltage wires have exhausted their service life;
• clogged idle valve;
• The mass air flow sensor is faulty;
• temperature sensor malfunction;
• valve clearance violations;
• the oil is out of season.

This is interesting: How to get to a gas station with an empty tank

Having considered possible malfunctions due to which the car may not start well when cold, let’s move on to studying ways to detect and eliminate them.

Toyota Camry won't start

One of the foreign cars that has problems starting the engine is the Toyota Camry. This model may have faulty wiring, spark plugs, and other difficulties. Note that Japanese and European cars are very similar; most of the faults in them are eliminated using the same methods.

The starter turns, but the engine does not start

If this problem occurs, you should first check the connectors and contacts in the engine compartment. Especially ones that fit into the fuse box or engine control unit. Over time, the contacts oxidize. One of the signs of this problem is a green or blackened connector. To eliminate the malfunction, the contact must be cleaned or replaced.

This problem is very easy to fix

Problems with the fuel system

First, you should check the fuel level; if the sensor or indicator on the instrument panel is faulty, you will have to check it manually. On gasoline engines: remove the fuel filter, remove gasoline.

To repair diesel engines you need:

Unscrew the tubes on the injectors. Start the starter. If diesel fuel comes out of the pipes, the fuel system is fine

Pay attention to whether there are air bubbles in the fluid. If there is air in the system, then there is a leaky connection somewhere

In this case, you will not be able to start the engine.

If there is air in the system, there is a leaky connection somewhere. In this case, you will not be able to start the engine.

Difficulties with spark plugs or injectors

If you suspect this malfunction, the spark plugs of a gasoline engine need to be unscrewed and inspected. If they are wet or have heavy carbon deposits on them, you will have to clean and dry them using a torch or on the stove at home. It is difficult to check diesel engine injectors yourself. Especially electronic ones. On some engines you can remove them, connect fuel supply pipes and electrical wires to them, and in this form crank the starter. An even spray pattern should emanate from the holes. If diesel fuel drips, then you need to take the nozzle for repair.

Injector contamination occurs due to the use of low-quality fuel

Engine control sensors are faulty

It is difficult to check the sensors yourself. To remove some of them, you will have to dismantle other elements:

• Crankshaft position sensor - you will have to remove the generator and route the wiring to the bottom. Resistance at positive temperatures: 985–1600 Ohms.
• Camshaft position sensor - located at the rear of the cylinder head. Normal resistance: 835–1400 ohms.
• Combined mass flow and intake air temperature sensor - if you disconnect the wire from the sensor, the car should start. But the engine may run intermittently.

Faulty sensors should be replaced with new ones.

The mounting block is filled with liquid

This problem can occur after extensive car washing. Moisture either gets inside the case or the connector contacts oxidize. The block must be removed, disassembled and dried. Clean or replace contacts.

To access the fuses, you need to press the latch and remove the cover, on the inside of which there are spare fuses and tweezers

Different car models have their own “weak” points. But in most cases, you should check them according to the usual scheme: first, simple faults related to the electrical and fuel system, then more complex ones.

Troubleshooting and troubleshooting in different types of engines

A problem with spark plugs is a common cause of poor starting in a cold engine.

Different types of engines have their own trouble indicators. It happens that a gasoline engine has difficulty starting when cold, and one of the main ways to find out the cause of the problem is the spark plug. It may also be the reason why diesel engines have trouble starting in cold weather. Indications for checking spark plugs, testing the battery, checking explosive wires and the ignition coil are jumping speed, engine tripping and poor cold starting, but only when the problems go away after warming up.

If the spark plug is dry, the problem is in the fuel line, as it indicates that fuel is not being supplied to the system.

Let's examine the spark plugs. Having unscrewed the spark plug, we carefully examine it. If the spark plug is wet, this indicates an overflow of fuel. Then suspicions fall on an electrical failure. We check the high-voltage wires, then we diagnose the ignition coil and battery.

We check the performance of the spark plug itself: serviceable spark plugs have a good spark. If the spark plugs fail, it is better to replace them with new ones. High-voltage wires can be checked in a dark room - if a glow is visible in the dark, the wires have been broken and they also need to be replaced.

Diagnosis of the causes of difficult starting

When a car has difficulty starting from a cold engine to a cold one, there may be different reasons. If the indicator is a dry spark plug, this is a sign of a problem with fuel supply. This can happen due to clogged filters - fine and coarse cleaning. If the engine still has difficulty starting when cold, pay attention to the injectors.

A faulty injector may be indicated by a spark plug flooded with gasoline after an unsuccessful start.

Another characteristic feature of this malfunction is poor starting in hot weather with a warm engine, and in winter problems arise with starting a vehicle that has already cooled down. You can check whether the problem is correctly detected by reducing the pressure in the fuel system before stopping the engine for an extended period of time. The injectors may be incorrectly adjusted or leaking. Additionally, we examine the fuel system for leaks, kinks or creases. Due to damage, air can leak inside and prevent the engine from starting when cold. It happens that the starter is fine, the spark plugs and wires are normal, but the engine does not start. Then you need to look for the cause in the sensor that regulates the coolant or check the pressure in the fuel system.

Wear of CPG parts

At first, this problem may only occur when the engine is started cold. The owner will notice terrible vibrations and a slight deviation in idle speed. As they warm up, the parts of the cylinder-piston group expand and the backlash goes away. The motor works as it should. But as soon as it cools down, the vibrations repeat again.

Wear of the cylinder-piston group

If you notice this feature, check the compression in the cylinders:

• for gasoline engines the normal value is from 10 to 14 Bar;
• for diesel engines - from 20 to 28.

The pressure difference across the cylinders should be no more than 10 percent. If the results are disappointing, it is worth performing an endoscopy of the engine. It happens that the “hon” on the walls is intact, but the compression is still low. There are several reasons. One of the simplest ones is burnout of the cylinder head gasket. If the gasket is intact, look at the valves and rings.

Occurrence of rings

A common cause of low compression is coked rings. This occurs due to the use of bad oil or fuel, or untimely maintenance. Decarbonization will help solve the problem, but this requires disassembling the engine.

Carburetor

The main reasons for poor starting of a carburetor engine after cooling to a cold state is the failure of the ignition distributor. Determined by cranking the starter - it turns out that the engine does not “grab.” The next reason is the ignition coil, the serviceability of which is checked with a multimeter. The switch, distributor, or carburetor settings may also be faulty. If a car with a carburetor is very difficult to start when cold, or after that it starts and stalls, this indicates a breakdown of the diaphragm in the starting device.

Idle speed control

The regulator tends to become dirty at a distance of more than 100 thousand kilometers. Because of this, the regulator rod begins to jam, and sometimes jams in one position. The speed fluctuates when cold, sometimes even when hot. At the same time, the motor rotates without problems under load.

Idle speed control

There are two options for solving the problem - disassemble and clean the old regulator, or replace the IAC with a new one. It is important to know that Chinese substitutes quickly fail, so try to buy original IACs or analogues from trusted manufacturers.

Injector and starting problems

Problems starting a cold injection engine

When a car cannot start when cold (cold engine), the injector installed on it requires a special approach to finding the reasons. In this case, first of all, you can turn your attention to the sensors. As a result of their malfunction, incorrect signals are sent to the electronic control unit. The functionality of the following sensors should be checked:

• throttle valve;
• fuel consumption;
• coolant temperature;
• mass air flow;
• The operation of the fuel regulator is often disrupted.

On cars with a mechanical injector, the root cause of poor starting is the starting injector. Probably, after these actions, the question is, “Why does my car have trouble starting in the morning when it’s cold with an injector inside?” will leave the owner of the car.

Diagnostics

Diagnosis of why the car takes a long time to start the injector So, to determine the specific reason for the long start of the injection engine, you should start with a high-quality diagnosis. Usually, they check the compression in the cylinders. Its values ​​must be within 12 atm for this to be considered normal. In this case, there should be no deviations between these indicators in each of the cylinders (maximum - 1 atm).

Then the spark plugs must be replaced. This will have an effect on the engine and it will now start much faster. However, if everything is not in order with the motor, then the normal starting time will last only 1-2 days.

Therefore, high-voltage wires should also be diagnosed. Diagnostics will make it possible to find out whether the cables have a breakdown, which is clearly visible by the spark coming out at night. This is done as follows: the car starts in the dark, at the same time you need to monitor which wire sparks.

The ignition coil also needs to be checked. Many experienced drivers do this: they install a known good and new module instead of the original one, then check the engine starting for several days. If everything is normal, the start-up does not take long - it means that the whole problem was in the bobbin (ignition coil).

If there are no changes, the test continues. This time you should test all filters, including the air filter. Next is checking and replacing all sensors and regulators.

Pay special attention to the mass air flow sensor. The next stage: testing various connections, checking the wiring for good contact, cleaning the masses and flushing the throttle assembly.

If nothing changes again, then it is recommended to check the engine fan relay. It often causes similar problems with starting on a fuel-injected internal combustion engine. You can test the relay if you remove the wire from the temperature controller installed on the thermostat.

The fan should turn on after these steps. However, after measuring the resistance value on a warm internal combustion engine, the system can produce low temperature data, although the temperature inside the engine is clearly more than 90 degrees. Why is there such a difference?

It turns out that this may well be a buggy DTOZH, which for some reason was not checked earlier. It must show the real coolant temperature, otherwise chaos will begin in the system, and it is not surprising that the engine takes so long to start.

Diesel engines

In a gasoline engine, troubleshooting should begin with the spark plugs, and when a diesel engine has trouble starting when cold, the reasons should begin with loss of compression. A loss of compression can be assumed when the car is started after acceleration by hand, and after that, blue smoke is observed from the exhaust pipe for some time. Low compression can occur if the valve clearances are set incorrectly. Another reason is that the timing belt is not installed correctly. If the compression is normal, you should pay more attention to the choice of high-quality fuel (its suitability for the season), fuel supply and the next reason - glow plugs.

The procedure for returning the car to “life”

Let's say you find yourself in circumstances where the injection engine starts poorly or refuses to do so at all. There is no need to hesitate in such a situation - it is advisable to immediately begin resuscitation procedures. If you don’t have time to figure out the exact reason why the car doesn’t start well, then you should quickly carry out the following algorithm of actions:

1. First of all, we check the availability of gasoline and battery charge. Is there something missing? Fill it up and light it up. Let's try to start. If there is no result, proceed to the next step;
2. Next, we quickly analyze under what circumstances the car malfunctions. If it takes a long time or is difficult to start when hot, we first check the spark plugs for overheating (light carbon deposits) and the functioning of the fuel system. Otherwise, when the car malfunctions both cold and hot, a more comprehensive approach is required. As a rule, the following procedures are sufficient: checking spark plugs, wiring the ignition system, assessing the operation of the injector and fuel system;
3. Note that most motorists manage to solve the problem, so to speak, with little loss, that is, by implementing the actions described above. If you are not one of the lucky ones and your car still takes a long time, starts poorly or refuses to work at all, you will have to act globally. Here it is better to take the car to a service station or a convenient garage and check the compression, timing adjustment, clean the injector, assess the condition of the fuel system and ignition devices. If there are any malfunctions, they must, of course, be eliminated.

In general, there are no particular difficulties in repairing a non-starting injector. The main thing in the process of such work is to act competently, in accordance with the procedure and possible vehicle malfunctions described above.

Starting in cold weather

Tips for winter starting the engine

If your car has trouble starting in cold weather, following simple rules can correct this situation.

Try to keep your fuel tank full to help prevent condensation from forming and mixing water with fuel. This way the quality of the fuel will not deteriorate.

A car that runs on gas and cannot start well when cold - never start it without switching to gasoline! Is it dangerous!

• Before starting the engine, when it is frosty outside, it is advisable to turn on the high beams and turn them off after a couple of seconds. This procedure will help partially restore the battery capacity and eliminate poor starting in cold weather.
• Before starting a car with a carburetor, you need to pump up the fuel a little (be careful not to fill the spark plugs!).
• After turning the key in the ignition, if the car has an injector, do not rush to start the engine. It is worth waiting a while for the required pressure in the fuel system to rise.

Starting the internal combustion engine. How does this happen

A car engine only works if several conditions are met:

1. A sufficient amount of air-fuel mixture enters the cylinders.
2. At a certain moment (at the end of the compression stroke), the spark plug generates a spark of the required power.
3. The crankshaft and camshaft rotate with strict interaction, ensuring timely filling of the cylinders with the combustible mixture, proper functioning of the gas distribution system and operation of the fuel pump in carburetor internal combustion engines.

By turning the ignition key, the driver supplies power to the starter solenoid relay, which turns on its electric motor and ensures engagement with the crankshaft flywheel ring gear. As the crankshaft rotates, it converts angular momentum into reciprocating motion of the pistons and drives the camshaft (or shafts). The latter ensures timely opening of the valves, due to which the combustion chambers are filled with the fuel mixture at the right time.

Reasons why the car doesn't start well when cold

On automobile forums you can often come across the question: why does the engine start poorly when cold? It happens that a person has driven a car for some time, parked it, the engine has cooled down, and when he needs to drive again, it either does not start at all or starts, but with great difficulty. Moreover, if the engine has not yet completely cooled down, then it starts up calmly. Why is this happening?

There are two basic reasons - either it is 1) a problem in the fuel supply, or 2) a problem in the ignition system.

The following malfunctions lead to incorrect fuel supply:

1. Poor quality fuel. 2. The injectors are clogged. 3. The coarse filter is clogged. 4. The fine fuel filter is clogged. 5. The throttle valve is clogged (cleaning the throttle valve). 6. The idle jet is clogged. 7. Insufficient pressure in the fuel pump. 8. Fuel pressure is not adjusted correctly. 9. The air filter is clogged. 10. The outside temperature is too low to start the engine.

Now you need to determine whether, in your case, there is a problem with the fuel supply - the spark plug will tell you about this. You need to turn the starter, unscrew the spark plug and inspect it: if it is filled with gasoline, it means that too much fuel is entering the combustion chamber; if it is completely dry, it means that not enough fuel is entering.

Next, refer to the list of faults for fuel supply problems listed above and identify this fault.

If the engine doesn’t start well when cold, but you still haven’t found any problems with the fuel supply, then the whole point is in the second reason: there is a problem in the ignition system.

The following reasons lead to malfunctions in the ignition system:

1. The spark plugs are worn out (how to check the spark plugs). 2. The battery is discharged, and the starter turns very weakly, at an uneven speed. 3. The ignition distributor is faulty. 4. The high-voltage wire is broken or punctured (in a dark place, when starting the engine, a glow will be noticeable on this wire). 5. The ignition coil is faulty (if there is only one, you can check it with a multimeter).

If the compression pressure in the combustion chamber has sharply decreased, this will inevitably lead to problems with fuel ignition.

Reasons for decreased compression pressure: 1) engine wear; 2) incorrectly set valve clearances (VAZ valve adjustment); 3) the timing belt is installed incorrectly.

Of course, if the car engine does not start well when cold, you should not immediately rush to disassemble the injector, reinstall the timing belt or repair the fuel pump. Still, such reasons happen quite rarely. You need to start by identifying simple causes and, as they are eliminated, approach more complex ones.

DTOZh replacement procedure and timing

The procedure for replacing the DTOZh may differ depending on the car model. At the VAZ, to carry out the process, you need to prepare several tools, including the obligatory set of wrenches. According to the classic scenario, the coolant will have to be drained, otherwise replacing the DTOZH cannot be called correct. Although there are several replacement options that do not involve draining.

As mentioned above, one of the DTOZH is located in the thermostat. It screws in from the side. The second is located a little lower, wrapped in the cylinder head.

A little about the timing of replacement of DTOZH. If we are talking about a regulator that goes to the pointer, then it must be replaced at the very moment when the temperature values ​​​​go astray. This is easy to check: for example, when the engine is cold, the coolant needle tends to the red zone or simply wanders.

This is an error and requires correction, i.e., replacement of the sensor.

In some cases, it also happens that it is not the regulator itself that is to blame, but the wiring or contact. You need to check everything, and only then decide whether to change it or not. Testing the wiring is also easy: the wires are disconnected from the DTOZH, the ignition is turned on and a short to ground is made. If the arrow jumps up, then everything is in order with the wiring.

The second DTOZH changes if the machine itself is not working properly. For example, the speed of a cold engine does not increase, but when it is hot it reaches a value of 1500 rpm. Fault number 2 can also be judged by the cooling fan, which turns on too early or does not do so at all.

Temperature controllers that have been removed are easiest to check. They must be immersed in boiled water heated to certain values, then connect an ohmmeter to measure the resistance coming from the DTOZH. Tired of paying fines? There is an exit!

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• Does not cause interference to radios and cell phones.

A car engine may have difficulty starting when cold under different conditions. Sometimes it happens that the car has been sitting in a garage or outdoors for quite a long time. A situation may also arise when the engine was running, then cooled down, but it does not start again.

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

Why does a car have trouble starting with a cold engine?

“It doesn’t start well when it’s cold,” such complaints can often be heard from drivers in cold weather when discussing cars. In this case, different symptoms and behavior may be described, but the problems due to which the car is difficult to start when cold are, as a rule, almost the same. The reasons for difficult starting may differ depending on the type of engine; since gasoline engines (injector or carburetor) have their own reasons, and diesel engines will, of course, have others.

Main reasons in the table

Symptoms

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If you press the accelerator before starting, the start will be faster. But at the same time, fuel consumption and engine warm-up time will increase until the speed drops to normal. Another inseparable companion of such a situation is black exhaust. Obviously, black smoke from the muffler directly indicates that the fuel is not completely consumed and remains in the cylinders.

Carburetor

The main reasons for poor starting of a carburetor engine after cooling to a cold state is the failure of the ignition distributor. Determined by cranking the starter - it turns out that the engine does not “grab.” The next reason is the ignition coil, the serviceability of which is checked with a multimeter. The switch, distributor, or carburetor settings may also be faulty. If a car with a carburetor is very difficult to start when cold, or after that it starts and stalls, this indicates a breakdown of the diaphragm in the starting device.

The main reasons why the carburetor does not start when cold:

1. Ignition coil.
2. Switch.
3. Distributor (lid or slider).
4. Incorrectly adjusted carburetor.
5. The starter diaphragm or the fuel pump diaphragm is damaged.

Of course, if you pump up gasoline before starting and pull out the choke more, it will start better, but all these tips are relevant when the carburetor is correctly configured and there are no problems with the switch or spark plugs.

If a car with a carburetor, be it a Solex or a DAAZ (VAZ 2109, VAZ 2107), starts up when cold and then immediately stalls, flooding the spark plugs, this indicates a malfunction of the starter diaphragm.

Possible faults

No matter how trivial it may sound, if the injector does not start, it means something has gone wrong. The success and speed of repair depends on how quickly and efficiently the problematic link in the car’s design can be identified. To better understand the essence of repair activities, it would be a good idea to pay attention to potential breakdowns. The basic list of the latter is as follows:

• Malfunctions of the injector itself. In the event of a breakdown of this kind, as a rule, the car does not start either cold or hot. On top of that, the injector indicator on the dashboard or on-board computer constantly lights up, signaling its malfunction. It is much less common for the engine to work when the indicator is on, but in this case the car starts poorly and is extremely unstable. It is worth noting that the injectors in the injector most often become clogged or the ECU burns out, so it is advisable to check these components first;
• Ignition system failures. Here the list of possible faults is quite large. Often the candles that suffer are simply flooded. In the event of such a breakdown, the car starts and immediately stalls, but in the long term it stops even “grasping.” Other components of the ignition system (coil, module, distributor, crankshaft sensor, etc.) are noticeably less likely to suffer;
• Incorrect operation of the fuel system. In this aspect, injection engines most often suffer on three fronts:
• Fuel filters are clogged (the car “picks up”, but does not start; if the engine starts, it is extremely unstable);
• The fuel pump is faulty (its characteristic operating sound is absent when you turn the ignition key, the injector itself simply does not start both cold and hot, the starter turns).
• There is insufficient pressure in the fuel system (the engine starts up reluctantly both cold and hot, but if it starts working, it functions unstable);
• Engine problems. Perhaps the widest range of possible malfunctions. Often the reason lies in weak compression or incorrectly adjusted valves. In any case, with a “motor” starting problem, high-quality engine diagnostics are required, otherwise it will be very difficult to determine the cause of the malfunction.

In addition to the breakdowns described above that can break the operation of the injector, the problem may lie in more trivial things. An example of this is a weak battery charge or lack of fuel in the tank. Considering just such incidents, before repairing a car, it is extremely important to exclude the possibility of their occurrence, so as not to waste extra time and nerves.

Injector and starting problems

When a car cannot start when cold (cold engine), the injector installed on it requires a special approach to finding the reasons. In this case, first of all, you can turn your attention to the sensors. As a result of their malfunction, incorrect signals are sent to the electronic control unit.

This is interesting: How to extend the life of an engine?

The functionality of the following sensors should be checked:

On cars with a mechanical injector, the root cause of poor starting is the starting injector. Probably, after these actions, the question is, “Why does my car have trouble starting in the morning when it’s cold with an injector inside?” will leave the owner of the car.

Diesel engines

In a gasoline engine, troubleshooting should begin with the spark plugs, and when a diesel engine has trouble starting when cold, the reasons should begin with loss of compression. A loss of compression can be assumed when the car is started after acceleration by hand, and after that, blue smoke is observed from the exhaust pipe for some time. Low compression can occur if the valve clearances are set incorrectly. Another reason is that the timing belt is not installed correctly. If the compression is normal, you should pay more attention to the choice of high-quality fuel (its suitability for the season), fuel supply and the next reason - glow plugs.

If a diesel engine has trouble starting when cold, the reasons can be collected in a single list of ten points:

1. Starter or battery faulty.
2. Insufficient compression.
3. Faulty injector/injectors.
4. Incorrectly set injection timing, desynchronization with fuel injection pump operation (timing belt jumps by one tooth).
5. Air in fuel.
6. The valve clearance is incorrectly set.
7. Malfunction of the preheating system.
8. Additional resistance in the fuel supply system.
9. Additional resistance in the exhaust system.
10. Internal breakdown of the injection pump.

Low battery charge.

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 is blinking - the battery terminal is dead.

If the car has an old battery installed, then everything is clear, it needs to be changed and the problem will go away. But it happens that the battery is normal and the capacity holds well. In this case, you need to look for a leak in the car's wiring. In car stores, they sell a special device that allows you to determine whether there is a leak in the car in quiet mode. Perhaps some electronic device is faulty and drains the battery. Either the non-standard radio is connected incorrectly, or simply some wire has become unusable and is causing a short circuit to ground (especially true for older 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 charge the battery completely. And since it is more difficult for a starter to crank a cold engine than a hot one, it will definitely start with problems.

About the causes of poor starting and how to combat them

The list of reasons why a cold engine is difficult to start is quite wide. Before starting diagnostics, it is necessary to more accurately localize the fault. Make sure the battery is charged and 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 both as a result of the fact that there is no fuel supply, and due to failures in the process of its ignition in the engine cylinders. As for the fuel supply, there may be too little fuel to start. It is also possible that the spark plugs are flooded with excess fuel.

1. It's worth starting the check by making sure there is an exhaust. If light smoke appears from the exhaust pipe after turning the starter, then this indicates that there is fuel supply to the cylinders.
2. The next step is to remove the spark plugs. The spark plugs must be unscrewed after an unsuccessful attempt to start the engine. If the spark plug is flooded with gasoline, then this can often indicate problems with injector sealing or ignition. Check the integrity of the spark plugs themselves and the high-voltage wires, and also make sure that there is a spark at the spark plugs. A dry spark plug will indicate that fuel is not being supplied to the cylinder.
3. Clogged coarse and fine filters, as well as faulty or heavily coked injection nozzles, can also hinder the normal supply of fuel to the engine. Fuel may also not enter the engine due to a sharp decrease in the performance of the fuel pump. This means that the fuel pump is not creating the required pressure. To find out the reasons, you will need to check the fuel pressure in the rail and the fuel pump itself.

An additional nuance may be air leaks in the fuel system. It is necessary to examine the lines for damage, bends, cracks, etc. Gasoline leakage is a clear sign of loss of seal in the fuel lines.

Electronic sensors

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

If the engine does not start, then you need to check several sensors:

• camshaft position sensor (CPR);
• throttle position sensor (TPS);
• mass air flow sensor (MAF);

It is also necessary to simultaneously clean the throttle, check the air filter and the XX valve. Self-diagnosis of sensors can be done 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 setting of the ignition timing, timing belt and its drive. In some cases, it is worth checking the condition of the variable valve timing system (if equipped). The ignition coil can be checked using a multimeter.

Compression reduction

A loss of compression in one or more engine cylinders is a consequence of natural wear or damage to the power unit. A motor with low compression does not, 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 time of start-up.

Frequent causes of this malfunction may be piston destruction, broken or stuck piston rings, burnout of the timing valve, wear of the cylinder walls, etc. Low compression most often appears during a cold start, but can also be present constantly (when trying to start a very worn engine “hot”). An engine with such a malfunction is most difficult to start at low temperatures. For an accurate diagnosis, compression must be measured.

Oxygen sensor

It is also a “lambda probe”. A sensor that analyzes the percentage of carbon dioxide in the exhaust. Interacting with the lambda, the ECU adjusts the mixture entering the combustion chamber. Note that this sensor only works in warm mode (from 300 degrees) - at a time when the probe is not warmed up, a slight fluctuation in revolutions is possible. This should happen for no more than 20 seconds.

Oxygen sensor

But if the engine continues to mope even at operating temperature, it is worth examining the lambda in more detail. Often this sensor becomes dirty or the contacts bend, causing the output voltage to change (more than 0.45 Volts) and the unit receives incorrect data. If computer diagnostics show errors in the lambda (there may be several of them), it is worth replacing the sensor and checking the engine operation again.

In general, the lambda probe is a common problem, both on our cars and on foreign cars. With our fuel quality, the sensors do not last more than 100 thousand kilometers and, from time to time, cause headaches for owners.

You can solve the problem radically - install “decoys” or reflash the ECU for Euro-2, while removing the catalysts. Or leave everything as is and just change the sensors periodically.

Take care in advance

In general, in cold weather, the alarm system’s already weakened battery is additionally drained. If the car is stored in a guarded parking lot, it is better to leave it unguarded, thereby increasing the chances of starting in the morning. In order to open the doors without problems, you need to keep a can of a composition called “lock defroster” in your clothing pocket all winter. It costs a penny, but it helps a lot when the key refuses to even “go” into the hole. If you don’t have a defroster at hand, you’ll have to test the old-fashioned method for yourself - warm the key with a lighter.

By the way, if you inject the same defroster or WD-40 into the lock in advance of frost, practically no water gets there. Do not use brake fluid to dissolve ice or treat locks. The lock may open, but by the evening it will freeze again, because, unlike special fluids, the brake fluid does not repel water, displacing it from the lock. In addition, it easily damages car paint.

Also, in severe frosts at night you can go out to warm the engine. Or pay parking attendants to warm up your car overnight. If possible, place it in the garage. Even in an unheated room, the temperature is 5-7 degrees higher than outside. And these are “two big differences” – minus 27 or minus 20.

If you still can’t start, and you have enough time, then you can try to determine the composition of the fuel mixture. To do this, simply remove one of the spark plugs from the engine and inspect it. If there are black (or very dark) deposits, the fuel mixture is quite rich, which means that there is something wrong with the car’s ignition system. Most often, in such cases, it is enough to replace the spark plugs, and engine starting returns to normal.

If there is no dark carbon deposit on the removed spark plug or it is white, we are talking about a lean fuel mixture. In this case, the culprit of the problem is often the coolant temperature sensor. You will always have problems with this - you will have to replace it.

When the fuel mixture is lean, some car owners try to start the engine using various additives that increase the octane number of the fuel. Sometimes they succeed. Another method that is often used in this situation is the injection of ether compounds to start carburetor engines. However, dealing with depressurization of the intake tract in the cold, and then doing all this in the reverse order, is not a pleasant task.

Another reason for a lean fuel mixture can be insufficient fuel pressure in the system. There are mainly two reasons here. This is either a dying fuel pump or a fuel pressure regulator. If there is a problem with the fuel pump, it may be impossible to start the engine. But sometimes the fuel pressure in the system can be raised to the optimal level by plugging the drain hose by squeezing it. This must be done carefully, as it may burst in severe frost. After starting the engine, you should not continue to pinch the hose. Otherwise, there is a high probability that the spark plugs will be splashed with too rich a fuel mixture. If this happens and the engine stalls, allow the mixture to evaporate by waiting 5-10 minutes. Or clean the spark plugs.

The most common cause of problems starting a cold engine can be the usual depressurization of the intake tract. Most often we are talking about a slipped (sometimes burst) tube that connects the fuel pressure regulator in the system to the intake manifold. Carefully inspect the connections of all tubes (hoses, etc.) that go from the intake tract to other systems or elements (brake system, adsorber, crankcase ventilation, etc.), and if there are serviceable elements of the injection system, problems with cold starting on your car will not.

Tips for starting the engine in cold weather:

1. Keep the tank full - this will prevent condensation from forming and water will not get into the fuel.
2. Turning on the high beams for a couple of seconds before starting will restore some of the battery capacity on frosty days.
3. After turning the key in the ignition switch (on an injection car), wait a few seconds until normal pressure is created in the fuel system, and only then start the engine.
4. Pump up gasoline manually (on a carburetor car), but you must not overdo it, otherwise the spark plugs will flood.
5. Cars run on gas, under no circumstances should you start them cold, switch to gasoline first!

Similar articles

How to start a car in winter

Many car enthusiasts live in regions where winters are harsh. Frost reaches -40, or even lower. Starting a car in such cold weather is not an easy task. It is not surprising that an experienced person will start his car in any frost, while an inexperienced person will experience problems even at -20C. There is an opinion that 8-valve VAZ 2110 starts better in cold weather than 16-valve ones. I don’t know why, but my VAZ 2111 (16kl) almost always starts the first time in cold weather down to -40 degrees. What are the secrets for starting a car in cold weather? What needs to be done with the car so that it starts even in severe cold? Let's try to understand these issues. So, the first rules that must be followed in order to start the car in cold weather without problems:

1. The car must be in good working order (for example, if in the summer your car started the second time or the starter turns for longer than it should, then in cold weather it will be much more difficult to start such a car)
2. A serviceable and well-charged battery (a very popular reason why car owners get into a taxi in the morning rather than into their car )
3. Motor oil should not be very thick.
4. Availability of high-quality gasoline.
5. High-quality alarm system (statistics show that more than half of the cases when they cannot start a car in cold weather is due to the alarm being blocked, because the Chinese relay freezes).

Procedure for starting a car in winter:

1. Turn off all electrical equipment (heater, headlights, heated seats or mirrors, etc.)
2. Turn on the ignition and wait (you need to wait until the Idle Air Controller (IAC) is set to its initial position.
3. Turn on the high beams for 15 seconds (this way we warm up the battery)
4. Depress the clutch and try to start (cranking the starter should not exceed 10 seconds)
5. If the car does not start, then wait at least 5 minutes (at this time you can watch how others are trying to start their cars to no avail )
6. We try to start it a second time. 2-3 attempts for 5-10 seconds, with a pause between attempts of 30 seconds.
7. If there are single flashes, but the engine does not start, then you should press the gas pedal to the floor and try to start it with the pedal held down for about 10 seconds. (cylinders are purged)
8. We try to start it one last time, if it doesn’t work, then there’s no point in trying to start it further. Most likely the candles were flooded.
9. We unscrew the candles. For 16kl, after removing the cover from the engine, unscrew the pin from the receiver and there is a through hole. It must be closed.
10. The spark plugs can be dried and cleaned, but it is better to buy new ones.
11. We remove the connector from the ignition module (IM) so that it does not burn out.
12. We turn the starter with the gas pedal pressed to the floor for about five seconds. (we blow through the cylinders)
13. We reconnect the MZ connector and screw in the spark plugs.
14. We're trying to start it. If again to no avail, then it is better to leave this disastrous business. Most likely there is a malfunction in the car.
15. If between attempts to start the car your battery runs out, you can try lighting the car using the battery of another car.

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Prevention of injector breakdowns

Why the injection engine does not start and how to eliminate possible problems is now known to all readers of our resource. However, it is better to avoid such breakdowns, so let’s pay attention to ordinary procedures that, if carried out systematically, will help minimize the risks of all malfunctions. The simplest but most effective prevention consists of the following measures:

• Firstly, refuel exclusively at proven gas stations and only with high-quality fuel. Remember that most fuel system and engine malfunctions are caused by dirty gasoline;
• Secondly, change all consumables on time and only with high-quality products. The most important thing is periodic replacement of all kinds of filters and engine oil;
• Thirdly, periodically check the main components of the machine for stability. The list of the latter, naturally, includes the injector, elements of the fuel system, ignition and engine;
• Fourthly, never neglect routine diagnostics of your car at a service station. Surprisingly, even a delay of a couple of hundred kilometers can cause serious damage, which previously could have been eliminated with very simple actions;
• And fifth, always operate your vehicle properly. That is, you do not need to overheat, overload or negatively impact your car in any other way.

Perhaps this is where the most important information on today’s issue has come to an end. We hope the material presented above was useful and provided answers to your questions. Good luck in operating and maintaining your car!