In the life of motorists, a situation often arises when, when driving out onto the road and trying to accelerate, it is noted that the engine does not pull.
That is, the acceleration dynamics are very “sluggish”, the car is reluctant to pick up speed, and it feels like something is holding it back.
This problem can arise with almost any car - domestic or foreign, gasoline or diesel, with a carburetor power system and injector.
Often, a drop in traction is accompanied by additional symptoms - extraneous sounds appear when the engine is running, the engine may stall in one of the modes (usually at idle), the crankshaft speed is not stable and “floats”.
But this is not always the case; it happens that the unit behaves perfectly in all respects, but does not develop power.
Main reasons
There are many reasons for this phenomenon and in most cases they are associated with a malfunction of the systems and mechanisms of the power plant.
Some of them are trivial and very easy to fix, others require quite serious repairs.
The main problem with the fact that the engine does not pull is not related to eliminating the malfunction, but to finding it.
In some cases, it is very difficult to determine what caused the reduction in traction effort and you have to go through almost the entire engine.
Therefore, we will try to indicate the main reasons why the car accelerates very “sluggishly”.
Since engines on different cars have their own design features, we will consider specific models.
How to determine the power indicators of a power plant
In the process of diagnosing 4-cylinder internal combustion engines, it is recommended to turn off three cylinders and use the resulting mechanical losses as a load. If diagnosing 6-cylinder or more power plants is carried out, additional load devices are used simultaneously with turning off a certain number of cylinders, which makes it possible to carry out the study much more efficiently.
Today, there are various techniques that help the owner independently check the power characteristics of the power unit of his car. For example, install special equipment that can monitor the slightest changes in the functioning of the internal combustion engine, a drop in dynamics, etc. But the price of such devices is quite high, and not every Russian motorist can afford to buy them.
Note. It is more advisable to install these devices on sports cars, the functioning of the internal combustion engines of which requires regular checks.
Fortunately for car enthusiasts, there is also a budget diagnostic option. It implies the presence of a computer, special programs and a cable for integration with the on-board computer (BC) of the car. As soon as the driver drives the car a certain distance at different speeds, the computer will automatically calculate the power of the car's power plant.
Attention. Despite the fact that this method of verification has a considerable share of errors in the readings, it is widely used by motorists in many countries around the world. The method gives at least a general idea of the power characteristics.
But still. Only a dynamometer can provide the most accurate indicators. Representing highly professional equipment, it is an indispensable component of any well-known car service.
Power drop on a VAZ carburetor engine
To begin with, let's take VAZ cars with a carburetor power system and an 8-valve timing system - VAZ-2109, VAZ-2110, VAZ-2114, VAZ-2115.
The same power plant is installed on these cars, so the reasons are identical.
Let's go through those components, due to malfunction of which a drop in dynamics may occur.
In general, the main reason that the engine does not pull is a change in the processes in the combustion chambers - a mismatch in the proportions of the air-fuel mixture, the combustion process is disrupted, the filling of the cylinders and the removal of exhaust gases does not occur as required.
Supply system
Very often, a drop in traction occurs due to the power system. Structurally, the carburetor fuel system used on cars from VAZ-2109 to VAZ-2115 is very simple and is almost completely mechanical, so identifying the cause is not particularly difficult.
A decrease in power can occur due to:
- Severely clogged fuel filter (its throughput drops and the pump is simply not able to pump the required amount of fuel);
- Contamination of the carburetor channels (the jets and fuel channels in this element have a small cross-section and debris often clogs them);
- There is air leakage in the area from the tank to the pump (because of this, the performance of the fuel pump drops sharply);
- Damage to the fuel pump membrane (a small crack in it leads to the fact that the vacuum required for pumping fuel is not created in the pump chambers);
- The fastening of the carburetor or intake manifold is loose (due to this, air leaks around the carburetor and the proportion of the air-fuel mixture is greatly disturbed);
- The hole in the fuel tank cap is clogged (because of this, a vacuum is created in the tank and it is much more difficult for the gas pump to pump gasoline out of it);
In addition to the elements responsible for supplying fuel, a drop in power also occurs due to severe contamination of the air filter element.
Ignition system
This system also takes part in the combustion of the mixture, which means a failure in its operation can affect power.
In carburetor engines VAZ-2110 and others, a decrease in traction can occur due to:
- Faulty spark plugs or changes in their thermal gap;
- Excessive wear of the contacts and the central electrode of the distributor;
- Voltage losses in high-voltage wires;
- Violations of the ignition timing.
Irregularities in the power supply and ignition systems most often cause a drop in power, so testing to identify the cause should begin with them.
If the operation of these systems does not raise suspicions, other components of the engine should be diagnosed.
Exhaust system, timing belt and crankshaft
Loss of traction can also occur due to the exhaust gas removal system, although problems with it rarely occur on carburetor engines.
The main reason here is the reduction in throughput due to large deposits in the muffler. Because of this, exhaust gases, without having time to escape from the cylinders, “choke” the engine.
The reasons for the drop in thrust are also often the gas distribution mechanism and the cylinder-piston group.
Here the reduction in power occurs due to:
- Violations of the thermal clearance of valves.
- Heavy carbon deposits on the valve plates and seats, or their burning.
- Occurrence of rings.
- Limit wear of the CPG.
- Cylinder head gasket failure.
In general, problems with the timing belt and CPG cause a drop in power in any engine - carburetor, injection, diesel. Therefore, we will not mention these mechanisms further.
What's the result?
With that said, if the engine is not making power, it could be due to the ignition, air or fuel supply. We add that a decrease in engine power can also occur depending on external conditions: ambient temperature and atmospheric air pressure.
If the car pulls worse under certain conditions, then this is not a malfunction. For example, high in the mountains, the power of an engine, especially an atmospheric one, decreases. Also in the summer, in extreme heat, the fuel pump or carburetor may overheat.
As a result, I would like to remind you that the throughput of the intake and fuel system greatly depends on the condition of the fuel and air filters. For this reason, filter elements must be changed promptly to ensure maximum performance from the engine.
VAZ injection engines
In injection engines VAZ-2110, 2112, 2114, 2115, both 8-valve and with a timing belt with 16 valves, it is more difficult to identify the cause of the decrease in power due to the more complex design of the main systems.
Supply system
Any injector consists of a mechanical executive part and an electronic control part, and problems can arise in both of them, which will lead to a drop in power.
Let's look at the mechanical part first. Here, cravings can be influenced by:
- Severely clogged mesh filter on the fuel pump;
- Decrease in fuel pump performance due to wear;
- The fine filter is dirty;
- Malfunction of the fuel rail pressure regulator;
- Clogged injectors;
- Fuel filter dirty;
- Air leak in the manifold.
In general, almost every element of the injector executive part can be the culprit for a decrease in dynamics.
The situation is approximately the same in the electronic component.
The operation of the engine with the injector is controlled by an electronic unit, which constantly monitors the parameters through sensors installed on different systems.
The number of these tracking elements is considerable and the breakdown of any of them leads to the fact that the ECU incorrectly evaluates the indicators on the basis of which it controls the executive part.
Thus, the lambda probe, DPKV, mass air flow sensor, DPZ, phase sensors, detonation sensors and coolant temperature sensors in the event of a breakdown lead to a decrease in power, so you will have to check all of them in search of the cause.
Ignition and exhaust system
As for the ignition system of injection engines VAZ-2110, 2112 and others, the reasons may be:
- Candles;
- High voltage wires;
- Ignition module.
Another possible cause could be a misalignment of the generator drive pulley (with the ring gear).
IMPORTANT TO KNOW: What is an adsorber in a car.
Because of this, the DPKV readings are disrupted, as a result the operation of the ignition system is disrupted, which leads to a drop in traction.
In injection engines, the exhaust gas removal system more often creates this problem than in a carburetor car, and all due to the use of a catalyst.
The element's honeycombs have a small cross-section, so they become clogged quite quickly, which leads to exhaust gases “crushing” the engine.
Also, if the engine does not pull, check the lambda probe.
I-Service
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Main reasons with engines of other cars
Next, we will go through other cars, and we will indicate the most frequently occurring problems that lead to a drop in power.
So, on a Mitsubishi Lancer 9, the problem most often arises with the exhaust gas exhaust system. This car uses a double catalyst, which becomes clogged with carbon deposits relatively quickly.
Therefore, many owners of this car, when the power drops, recommend first of all paying attention to this system.
But in the ZMZ-406 and 405 engines, which are equipped with GAZelle and Volga cars, a drop in power often occurs due to:
- Ignition coil malfunctions;
- Losses in high-voltage wires;
- Non-working spark plugs;
- Failure of sensors (primarily DPKV).
But do not forget about the other above-mentioned elements of the power supply, ignition, as well as timing and CPG systems.
In Ford Focus cars, in general, problems with loss of traction arise due to malfunctions of sensors, as well as elements of the power system - especially the fuel module, which includes both a fuel pump and a filter, combined into a single structure.
Much the same applies to a car like the Renault Megane.
In this machine, power loss may occur due to:
- Wear of the distributor cover;
- Faulty spark plugs and high voltage wires;
- Weak exhaust system capacity;
- Worn fuel pump and dirty filter elements;
- Damaged injector sensors.
In general, first of all, you should look for the cause in the power and ignition systems, and only then move on to the timing belt and CPG.
Poor throttle response due to clogged catalyst
As you know, power can be lost due to debris in the catalyst located in the muffler. How can I check this?
- Measure the pressure in the exhaust system. If the obtained value is more than 0.5 atmospheres, the catalyst needs to be replaced or removed.
- After warming up the engine well, measure the temperature of the exhaust pipe before and after the catalyst. If the temperature before and after is the same, the catalyst is clogged. Likewise if the temperature after is lower.
- Ringing inside the catalytic converter.
If there are problems with the catalyst, you should not remove it without subsequent replacement. Extraneous noise and overall engine noise will increase, the resonance of the exhaust system will be disrupted, but this has virtually no effect on engine power. It is better to install a new catalyst than to drive without it.
If the diesel engine doesn't work
A decrease in traction can also occur in diesel engines. If we look at old cars that have completely mechanical power systems, then the most common cause is depressurization of the system.
As a result, air enters the fuel, which is why the fuel injection pump is unable to provide the required pressure.
Don't forget about:
- clogged filters;
- weakly pumping fuel priming pump;
- damaged plunger pair;
- Coking of injector nozzles.
And if we also add possible problems with the timing belt and CPG, then identifying the cause will not be so easy.
In modern diesel installations, where an additional electronic component is used, the search range will increase.
For example, the Common Rail system uses all the same sensors as the injection engine. And if at least one of them breaks, this will certainly affect the operation of the control part.
Violation of valve timing
The main parts of the gas distribution mechanism (GRM) are the intake and exhaust valves. They are “obliged” to open and close only at the right moment so that the fuel mixture enters the cylinders on time and exhaust gases are removed. This process is called phase distribution. If it is violated, you will see that the power of the engine has disappeared, which will begin to “triple” and sometimes have difficulty starting.
Causes of valve timing violations:
- wear, as well as incorrect installation, displacement of the chain or timing belt (most often this is a jump by one tooth (link));
- play or deformation of the pulley on the crankshaft;
- wear of hydraulic compensators, camshaft and (or) its bed;
- burnout or rupture of the head gasket;
- Malfunction of the camshaft position sensor (DPRV).
To restore normal operation of the timing belt, it is necessary to set the position of the timing and crankshaft shafts according to the marks. If the chain is worn, replace it. The same applies to the camshaft with a bed, hydraulic compensators, gasket and DPRV.
The clutch is acting up
When the car suddenly stops pulling, the clutch may be slipping. In this case, the contact between the motor and the transmission is weak, and the rotational energy is not completely transferred to the wheels. A clear sign of such a problem in a car with a manual transmission is the appearance of noise and the unpleasant smell of burnt linings. You should go to a service station for repairs as soon as possible. By delaying the repair, you will receive a complete replacement of all parts of the clutch assembly and flywheel in addition, because its contact surface will be irreparably worn out.
If the clutch does not work well, the car gains speed, but does not move. The clutch can malfunction not only in manual transmissions, but also in robotic units. The cause of slippage is automatic transmissions and even CVTs if the torque converter locking device has malfunctioned. The clutches can also slip, and in the variator there can be a V-belt.
Failures in the operation of torque converter locks, compression clutch drives and pressure supply devices to control the movement of cones can occur due to problems with the electronics that control them or the mechanisms that perform these actions, hence the loss of traction.
Stop driving with the handbrake, and traction will appear by itself
If you always set your car's handbrake but forget to release it while driving, prepare for compromised traction. When driving with the handbrake, you get the feeling that the car accelerates very slowly and it is too difficult to gain momentum. The driver immediately puts pressure on the engine, putting pressure on the suspension or gearbox. But he can’t even think that it’s enough to lower the handbrake lever for the problem to solve itself. Moreover, driving with the handbrake for quite a long time will cause the following troubles with the car:
- the rear brake discs (or drums, depending on the design of the car) become too hot;
- heating sometimes causes deformation or excessive wear of these parts with various consequences;
- wear in any case will be very high and will become the reason for the mandatory replacement of the pads and disc after 100 kilometers of such a trip;
- the drum brake may even fall apart during movement, reducing the safety of the trip;
- Heat and excessive friction can cause failure of some parts of the chassis;
- The brake system may also develop other problems that require immediate solutions.
These are the troubles that await you if you simply forget to remove the handbrake lever to its original position before moving off. If you have a manual transmission, keeping an eye on the handbrake becomes even more difficult. With an automatic, it is enough not to accelerate from the first second, but to let the car show its readiness for the trip, let it start idling. If you regularly leave the handbrake on, just stop using the handbrake. Leave it in gear, choose more or less level parking spots.
Exhaust system resistance
Many people consider the only task of the exhaust system to be to muffle loud sounds and remove exhaust gases. However, modern cars are equipped with a catalyst that reduces the level of emissions of harmful substances. If this element is heavily contaminated or destroyed, the passage of gases becomes difficult. As a result, the engine works “as if strangled.”
In Russia, the problem is solved by simply removing the catalyst. However, you need to remember that in some car models such an operation will require changes in electronics (programming).
Removing the catalyst
Check the air filter
A filter that is too dirty does not allow enough air to pass through to create a fuel mixture. This can lead to a significant drop in engine power and fuel consumption will increase significantly.
In addition, the quality of the materials used in it can also affect the operation of the motor.
There are many different stories about cheap and unoriginal filters. These products break, and then a series of serious malfunctions follow the chain, including failure of the piston rings. To check the condition of the air filter, you need to open the hood, remove the element from the housing and visually assess the condition. If necessary, the part is changed immediately.
Why is it better to solve the problem with traction at a service station?
Of course, if poor traction is due to a forgotten handbrake or bad fuel, no service will help you. Unless you need to eliminate the problem of increased wear of the brake discs. In other cases, it is better to immediately contact a service station and not experiment with independent repair options. This way you can restore your car in a short time, without having to check possible theories of failure. The main benefits of service in this case for professionals will be the following:
- specialists will find the cause of the problem and will be able to completely restore normal operation;
- the service will recommend that you change your driving habits so that you don’t end up in this situation in the future;
- The company will purchase all spare parts independently, which reduces the risk of purchasing low-quality parts;
- diagnostics will show the exact part that is worth restoring, which can often save you money;
- The repair will be carried out professionally, you will be given a guarantee for the serviceability of the repaired unit.
These are important advantages of servicing your car with specialists, so it is better not to neglect them and get maximum comfort in operating your car. You will often have to overpay for expensive professional services, but this overpayment will definitely pay for itself. After completing the repair at a good station, you will not have to worry about possible repeated problems with traction. However, the health of a car in most cases depends on the driver’s behavior and habits on the road. Therefore, if a certain problem constantly arises in your car, just change your driving style. If you have a domestic car, you can watch the following video describing possible problems when the car loses traction:
Compression reduction
Often, the reasons for loss of engine power can be associated with simple wear and tear of the power unit. Do not forget that a car aged about 100 thousand kilometers begins to lose its power by 10-15%. If you think the losses are excessive, you need to check the compression. Its nominal value is indicated in the documentation for the machine. For testing, you will need an inexpensive device - a compression gauge, which is a pressure gauge mounted on a hollow tube or connected to a rubber hose equipped with a tip. It is screwed into the cylinder block instead of a spark plug. Next, disconnect the high-voltage wire from the ignition coil. Crank the crankshaft with the starter and note the highest reading on the compression gauge. The operation should be repeated for each cylinder.
Compression check
Pressure below that specified in the instructions by more than 15% indicates wear of the rings, pistons, cylinder block walls, and valves. To solve the problem, you can bore the BC to the repair size, replace the piston rings, grind (or replace) the valves.
Air flow and pressure sensor
These two elements determine how much air the engine consumes, as well as how much air is needed to create the optimal air-fuel mixture. If these sensors fail, then the ECU will not make the calculations correctly and, accordingly, traction may be lost. If the car does not pull, the reasons (including the VAZ-2110 injector) may be in these sensors. If necessary, they should be replaced, and then the power will return again.
But if the car has an ECU, why doesn’t the corresponding light on the dashboard light up? The electronic control unit is programmed for an open or short circuit. If there is none of this, and the sensor simply does not work as it should, the computer will be able to report that the mixture is being prepared incorrectly. If the car pulls poorly, there may be other reasons, but it’s worth checking the sensor. You will have to look for the source of the sensor’s malfunction yourself. The parameters of a specific element can be found in the instructions.
Malfunctioning spark plugs
The planned replacement of these elements of the ignition system is carried out after 20-30 thousand kilometers. If the spark plugs are platinum, the resource increases to 100 thousand km. However, the situation when candles (most often one of them) fail ahead of schedule is not uncommon.
You can see and hear this by a number of signs:
- the engine starts with difficulty, especially in winter;
- idling is unstable, the tachometer needle jumps, the engine may stop periodically;
- when the power unit is operating, increased vibration is observed, for example, the gearbox shift lever shakes;
- poor acceleration dynamics - the car does not develop full power, it stalls;
- when you press the accelerator, “dips” are noticeable;
- fuel consumption has increased.
When one spark plug does not work, experienced drivers say that the engine is “troubling,” that is, only 3 out of 4 cylinders are working.
To find a faulty part, you need to:
- put on dielectric rubber gloves;
- with the engine running, disconnect the high-voltage wire from each spark plug one by one;
- in this case, the nature of the engine’s operation should change, the speed should drop, but if this does not happen, it means that the cylinder is not working - the spark plug does not produce a spark.
It is worth finding out the reason for the poor performance of the part; it is quite possible that it is defective. If other spark plugs subsequently begin to fail, you will have to look for the cause elsewhere - the CPG or the fuel system.
Checking the transmission
Sometimes the power unit can develop serious power, but it does not reach the wheels. If while driving you hear that the engine is working hard, but you don’t feel speed, then perhaps the automatic transmission system is slipping or there are blockages on the brakes.
To check, you need to drive onto a straight section, set the automatic transmission selector to position D, and then see how the car behaves. If the speed decreases, then the brake system should be diagnosed. If everything is fine with the brakes, you need to go to a good service station and check the automatic transmission.
You can also check the parking brake. To do this, you need to go to free space. Warm up the car and then pull the handbrake. Next, press the brake pedal and set the gearbox selector to position D. Next, press the accelerator. If the engine keeps the rpm around 2000, then everything is fine with it. If it is less or more, you should go to a service station to test the automatic transmission.
Automatic transmission malfunctions
One of the tasks of the gearbox is to transmit torque to the wheels. And if this process is disrupted, then the engine does not gain momentum. You step on the gas and the acceleration is sluggish. The whole point may be a slipping automatic transmission.
There are several reasons for this:
- low-quality gear oil or not what the manufacturer recommends;
- clogged filters;
- clogged valve body channels;
- faulty solenoids (in this case, slipping is observed “hot”);
- wear of friction clutches (maximum service life 200-300 thousand km);
- problem with the control unit.
Most of the above faults are difficult to eliminate in a garage. Therefore, you will have to use the services of a specialized technical station.
