It happens that you urgently need to go to work, and the car, after standing all night, will not start. So why suddenly quite serviceable after the last trip transport suddenly refuses to start? Or stalls, barely having time to scroll the engine? Let's analyze the reasons why a car can start badly on a cold one.

First of all, you need to make a reservation - your car starts up fine if the engine has not had time to cool down, but in the case when the vehicle stands 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. It is the situation when a cold engine does not start well and we will consider in more detail.

Causes of trouble starting a cold engine

When determining the reasons why the car began to start poorly on a cold one, first of all, you will need to make sure that the battery is not discharged, the starter is in good condition (it turns the engine calmly and evenly). A separate reason that requires an exception is refueling a car with low-grade gasoline. The quality of the fuel being poured greatly affects the trouble-free start of the vehicle. If the battery discharge is excluded, the starter is in good condition and the fuel is of appropriate quality, the following main problems can be suspected if the vehicle is difficult to start when it is cold:

• the fuel pump is out of order;
• the fuel filter is clogged (due to low-quality fuel);
• nozzles clogged (due to fuel);
• the fuel pressure regulator has malfunctioned;
• air suction;
• exhausted spark plugs, ignition coils, high-voltage wires;
• clogged idle valve;
• the mass air flow sensor is defective;
• malfunction of the temperature sensor;
• violations of valve clearances;
• the oil is out of season.

Having considered possible malfunctions, due to which the car can hardly start on a cold one, let's move on to studying ways to detect and eliminate them.

Troubleshooting and troubleshooting in different types of engines

Spark plug problem is a common cause of poor cold start

Different types of engines are characterized by their own malfunction indicators. It happens that a gasoline engine does not start well when it is cold, and one of the main ways to find out the cause of the problem is a spark plug. It can also be the reason that a diesel engine does not start well in cold weather.
Indications for checking the candles, testing the battery, monitoring the BB wires and the ignition coil are jumping speed, engine tripping and poor cold starting, but only when the problems disappear 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.

Explore spark plugs. Having unscrewed the candle, we carefully study it. If the candle is wet, then this indicates a fuel overflow. Then suspicions fall on a failure in the electrician. We check the high-voltage wires, then we diagnose the ignition coil and battery.

We check the performance of the candle itself: in serviceable candles - a good spark. In case of failure of candles, it is better to replace them with new ones. High-voltage wires can be checked using a dark room - if a glow is seen in the blackout, the wires have broken through and they must also be replaced.

Diagnosis of the causes of difficult starting

When a car does not start well with a cold engine on a cold one, the reasons may be different.
If the indicator is a dry candle, this is a sign of a problematic fuel supply. This can happen due to clogged filters - fine and coarse cleaning. If the engine still does not start well when cold, pay attention to the injectors.

Injector malfunction may be indicated by a spark plug filled with gasoline after a failed start.

Another characteristic feature of this malfunction is poor starting in the heat with a hot engine, and in winter problems arise with starting an already cooled down device. You can check whether the problem is correctly detected by reducing the pressure in the fuel line system before turning off the engine for a long time. Nozzles may be misadjusted or misfiring.
Additionally, we examine the fuel system for the presence of streaks, kinks or creases. Through damage, air leakage can occur inside and prevent the engine from starting on a cold one.
It happens that the starter is in order, the candles, 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 line system.

Carburetor

The main reasons for a poor start of a carburetor engine after cooling down to a cold one are the failure of the ignition distributor. It is determined by turning the starter - it turns out that the engine does not "seize". The next reason is the ignition coil, the health 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 on a cold one, or after that it starts and stalls, this indicates a broken diaphragm in the starting device.

Injector and starting problems

Problems with starting a cold injection engine

When a car cannot be started on a cold (cooled engine), the injector installed on it requires a special approach to finding the causes. 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. Check the performance of the following sensors:

• throttle valve;
• fuel consumption;
• coolant temperature;
• mass air flow;
• the fuel regulator often fails.

On cars with a mechanical injector, the starting injector is the root cause of poor starting.
Probably, after these actions, the question is, “Why does my car start badly in the morning on a cold one with an injector inside?” leave the owner of the car.

Diesel engines

In a gasoline engine, troubleshooting should begin with spark plugs, and when a diesel engine does not start well on a cold one, the reasons should be started with a loss of compression. It is possible to assume a loss of compression when the car starts after acceleration by manual forces, and after that it is observed from the exhaust pipe for some time. Low compression may be in case. 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.

Cold start

Winter Starting Tips

If your car does not start well in cold weather, following a few simple rules can correct this situation.

• Try to maintain a full tank of fuel - this will help to avoid condensation in it and mixing water with fuel. So the quality of the fuel will not deteriorate.

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

• Before starting the engine, when it is cold outside, it is advisable to turn on the high beam, and turn it off after a couple of seconds. This procedure will help partially restore battery capacity and eliminate bad winding in cold weather.
• Before starting a car with a carburetor, you need to pump up a little fuel (carefully so as not to fill the candles!).
• Turning the key in the ignition, if the car is equipped with an injector, do not rush to start the engine. It is worth waiting for some time in order to have time to rise the necessary pressure in the fuel system.

Many owners of diesel engines after a long overnight stay are faced with the fact that the car refuses to start, or the engine starts poorly - it vibrates, stalls. What are the reasons and what to do to facilitate the cold start of a diesel engine?

Why is it difficult to start a diesel engine "cold"

It is difficult to start the engine in cold weather. This is especially true for diesel units.

There are many reasons why an engine does not start well when cold. Let's list some common ones.

• low compression in the cylinders
• frozen fuel lines and fuel in them
• engine oil thickened
• low battery level, faulty starter
• failed glow plugs
• air in the fuel system
• faulty injection pump and injectors

low compression in the cylinders

If the engine is old enough, the reason why it is difficult to start it in the cold may be low compression in the cylinders.

The problem in this case will manifest itself mainly after a long downtime. And restarting an already warm engine will be difficult. After starting, such a motor will “troit”, the revolutions on it will float during the ride. At idle, the diesel vibrates strongly and may even stall.

The reason for such unstable operation of the diesel engine lies in the heavily worn parts of the CPG: gaps form between them, the tightness of the cylinders drops, and the compression decreases. As a result, the fuel-air mixture is not compressed enough and heats up, that is, it cannot ignite.

And after the diesel engine reaches its operating temperature, under the influence of heat, the gaps between the elements of the CPG are reduced, the compression increases and the engine becomes more stable.

frozen fuel

The most common and well-known reason why it is difficult to start a diesel engine in winter. After overnight parking, diesel fuel can thicken and turn into a waxy gel. Especially if, with the advent of cold weather, the owner did not switch to “winter” diesel fuel.

When paraffin crystals form in diesel fuel, they clog the fuel filter. Therefore, the main recommendation to all diesel owners is to change the fuel filter before the cold season annually.

Heating the fuel system (with a blowtorch, for example) and adding anti-gel additives to the fuel will help to cope with the problem. In advanced cases, it will be necessary to flush or even repair diesel fuel equipment.

Another reason why fuel is not pumped through the lines is that water got into it and froze in the filter.

Water can get into the fuel tank as a result of condensation on its walls or precipitate in the tank if the fuel is of poor quality. To prevent the problem, the tank must be kept as full as possible in the cold, and a dehydrogenating additive can be added to the fuel.

thickened engine oil

If the oil in the diesel crankcase is too thick or not suitable for winter operation in terms of viscosity, the engine will not start.

Therefore, it is useful to pull out the dipstick and assess the condition of the oil. If it does not flow, you need to change the engine oil, lowering its viscosity.

We wrote about how to choose the right engine oil.

The battery is dead, the starter is stuck

The battery in cold weather copes with extreme loads.

If it is old or its charge level has dropped after overnight parking, the crankshaft will not turn at the required frequency to create pressure, and the glow plugs will not warm up to properly heat the fuel-air mixture in the cylinders.

It is more difficult for the starter to crank the crankshaft in the cold due to the engine oil thickening in the cold. If it is worn out, it can wedge - and then the starter turns, clicks, but does not start the engine.

failed glow plugs

Glow plugs make it easier to start a diesel engine by heating diesel fuel in the cylinders. The candles are fed through the relay, and their heating is controlled by the control unit, taking into account the specified time, after which the relay stops transmitting voltage to the glow plugs.

A malfunction of the glow plugs is not easy to determine: even if 1 or 2 candles fail, the engine can hardly start, but even if it is -5 outside.

Poor-quality glow plugs fail literally in one season, so you can’t save on the quality of candles.

Check the glow plugs by unscrewing them and measuring the resistance. The fact that the problem is with the glow plugs, the owner will be prompted by a delay at the moment the motor seizes. And a cold internal combustion engine will “troit” at the time of launch and require support from the starter.

A sign of a malfunction of the relay or control unit will be the absence of a characteristic sound (quiet click) at the moment the key is turned in the ignition before starting the diesel engine.

air in the fuel system

The difference in the design of a diesel engine is that air and fuel enter the cylinders separately. If an air lock forms in the fuel system, the engine will stall.

Air enters the fuel lines through the areas of violation of their tightness. To remove the plug, the injection pump and lines are pumped.

faulty injection pump, injectors

Total

As you can see, there are plenty of reasons why a diesel engine does not start in cold weather.

In order to successfully start a diesel engine in the cold season, you need to prepare for the onset of cold weather:

• recharge the battery (replace with a new one), make sure the generator is working
• change engine oil and filter
• check glow plugs
• change fuel filter
• switch to "winter" solar
• drive with a full tank

In most cases, even if these measures are observed, there will be no problems with starting a diesel engine on a cold one.

But if the engine does not start when cold, try adding warm fuel to the tank or warm up the diesel fuel in the lines by directing a building (household) fung to the fuel filter and gas tank. Then warm up the diesel for XX minutes 10-15, until the warm fuel drains back into the tank, and hit the road.

If the problem is a discharged battery, try to “light up” the engine, or better, remove it, warm it up and charge the battery.

• We wrote about how to properly start a diesel internal combustion engine in winter.

Fuel pumps, injection pump for diesel engines you will find in our catalog

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 warming up during low temperature conditions;
• the possibility of programming the electronic control system depending on the manner and style of driving;

The principle of the engine

According to the principle of operation, injection engines are similar to diesel ones: fuel is supplied through special nozzles. After the starter starts to crank the crankshaft, the control sensors send a signal to the electronic control unit, which indicate what cycle the cylinders are in.

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

DMRV value table.

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 transmits voltage to the desired cylinder. The task of correct voltage supply is provided by two transistors located in the control unit housing.

Further, when the ignition of the working mixture occurred, the stroke of the cylinder began 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 on the exhaust system. Using the indicators received from the sensor, the control unit adjusts the composition of the mixture, sets the nozzle opening time. If there is a lack of oxygen at open throttle, the ECU opens the idle speed control slightly.

Causes of improper operation of the injection engine

The reason that the injection engine does not start well on a cold one can be several. The main one is a malfunction of the sensors.. If one of the modules fails, 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 leak

Occurs when there is a leak in the parts of the air supply system. The mass flow sensor cannot capture some of the air entering the engine, which is why a lean mixture is supplied to the combustion chamber. This results in erratic idling and a cold start problem for the injection engine.

During warm-up or choke operation, this problem is almost not noticeable, but when the engine warms up to operating temperature, interruptions in idling become more noticeable.

Air leakage can occur for the following reasons:

• violation 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 the fault significantly affects idling and starting a cold injection engine, before repair is carried out, you can increase the speed by disconnecting the plug from the mass flow sensor. Such an action will lead to a significant increase in fuel consumption, so it is not recommended to delay the repair.

With a slight suction, it is enough to adjust the fuel supply using the L-probe device.

The main indicators of the fuel and air mixture

Mass of fuel, kg.	Air mass, kg	Excess air coefficient	Mixture names	combustion rate	Engine power	Application mode
>1:6		<0,41	The mixture is not flammable
1:6	1:11	0,41 - 0,75	rich	reduced	reduced	Cold start
1:11	1:13,7	0,75 - 0,92	Enriched	Maximum	Maximum
1:13,7	1:15,4	0,92 - 1,05	Normal	Medium	Medium	Used with exhaust gas converter
1:14,7		1	Stoichiometric	Medium	Medium	Used with a neutralizer
1:15,4	1:17,7	1,05 - 1,2	depleted	reduced
1:17,7	1:20	1,2 - 1,36	poor	Dramatically reduced	Loss of power	Not applicable
<1:20		>1,36	The mixture is not flammable

Mass flow sensor failure

Incorrect operation or breakdown of the sensor leads to an instant stop of the motor after starting. When this happens, you need to disconnect the sensor and restart the car. If the engine runs without interruption, then the flow sensor needs to be replaced.

Faulty temperature sensor

When the central control unit does not receive signals from the coolant temperature module, it takes a value of zero. 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 on a cold one;
• detonation at low speeds.

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

Faulty ignition

You can fix the problem by setting the spark timing, adjusting the position of the timing belt and replacing damaged parts.

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

A failure in the fuel regulator causes fuel to leak into the combustion chamber through the intake manifold pipes. As a result, an enriched mixture enters the engine, which leads to severe clogging 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 nozzle supplies 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.

A car engine may not start well when cold under various conditions. Sometimes it happens that the car has been standing in the garage or in the open air for a long time. A situation may also arise when the engine has been running, then it has 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. With a cold start, it is also important to consider the ambient temperature at 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.

The main causes of poor cold start

There are several main reasons why starting a cold engine will be difficult or even impossible. To understand 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. Next, it is necessary and rotates the motor at the same speed. If you refueled with low-quality gasoline, then this can also lead to the fact that your car engine will not start well when it is cold.

Fuel supply problems.

Cold starting 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, 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.

Checking the fuel system must begin with an exhaust check. If, when the engine is rotated by the starter, a small amount of smoke comes out of the exhaust pipe, this indicates that ignition processes are taking place and fuel is being 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 happen as a result of injector leakage or ignition failure. 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 (presence of a spark) of all candles.

Poor supply of the fuel mixture to the cylinders may be due to clogged fine and coarse filters. A kind of coating may 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 fuel pump simply does not create the desired 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 determined by the places of leakage.

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 failure occurs with one of these sensors, then the corresponding signals will not be sent to the main control unit, as a result of which the engine will no longer start normally.

First of all, it will be necessary 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;
• DMRV sensor, which indicates the air flow in the system.

Ignition problems

When malfunctions 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 correctly set the ignition timing, for each brand of car, 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. To check you will need special tools and fixtures.

Hard start when cold :pengine compression problems

As a result of long-term 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 starts very badly, because all the gaps between the main parts in the cylinders increase significantly. This leads to the fact that the necessary pressure is not formed in the combustion chamber, which is necessary for starting.

VW vehicles are mainly equipped with Bosch Motronic engine management systems versions 2 7 and 2 9. Mono-Jetronic, Mono-Motronic121,123 13 KE-Motronic11, 12 and KE-Jetronic

Driving a road train under various road conditions

General rules for driving a road train

It is much more difficult to transport goods on road trains than on conventional trucks, therefore, in order to work on a road train, the driver must carefully study the device of this vehicle, its purpose, the nature of possible malfunctions and methods for their elimination, as well as know the overall dimensions and minimum turning radius of the road train.

Checking the operation of the fuel pump of injection engines

When the ignition key is turned on, the main ECM relay and the fuel pump relay are turned on.

The characteristic sound of a running pump can be the first sign of its operation.

Bad start of the injection engine

stepper motor

A malfunction of this element does not allow idling (the engine does not have enough air).

The vehicle can be driven if the throttle pedal is kept idling when the load is removed.

Idling injection engine

The idling mode is determined by the engine management system with the following:

Throttle closed

Increased fuel consumption in injection engines

High fuel consumption during the operation of a vehicle equipped with an ECM is usually attributed to electronic malfunctions.

Especially if the exact same car consumes fuel very economically.

Diagnostics of injection engines with malfunctions

Consider the main faults:

1 - when the engine does not start;

2 - when the operation of the engine does not meet operational requirements.

Diagnostics of injection cars VAZ without malfunctions

To diagnose the control system of the ECU of such cars, only a diagnostic tester and a gas analyzer are enough.

We check the errors on the tester, which were memorized during the operation of cars. For ECU Mikas, if there were fault codes:

Once again about the diagnosis of VAZ using instruments

Some subtleties that you should pay attention to when carrying out diagnostics in order to exclude the search for a faulty part by trial replacement

ECU VAZ and GAZ with 55-pin connectors. Contact Description

The car pulls poorly;

Interruptions in work

The immobilizer does not work well (it is not always possible to start the engine)