During the operation of various vehicles, drivers are often faced with the fact that the engine begins to twitch and jerks when the gas pedal is pressed sharply. Such, and on idlingif you press the gas hard. At the same time, in the usual mode (pressing the accelerator smoothly), noticeable jerks are often not observed.
In this article, we will talk about why such jerks occur and the car jerks when accelerating, the symptoms clearly indicate that the engine has begun to twitch, as well as how to identify and fix the malfunction.
The car twitches when the gas is pressed sharply: why is this happening
First of all, it should be understood that jerks and jerks when pressing the gas are most often associated with the quality of the fuel-air mixture. The mixture can be lean or rich.
A fairly common situation during the operation of the vehicle is one when failures occur when the gas pedal is pressed, the engine stalls during gas overload, power unit does not gain momentum, chokes, etc.
Many drivers wonder why the car jerks when pressing or releasing the gas pedal. Moreover, this problem manifests itself both on carburetors and injectors. And not every car service can find a reason. This is due to a large number of problems that can cause this behavior of the car. Often, a car enthusiast, having traveled to specialists, friends, as well as visiting several shamans, simply gets used to the idea that his car has such a feature. But, in fact, there is no such problem that cannot be eliminated (the only fatal problem of crickets in the "nine"), if you carefully check everything possible reasonsthen you can find the fault.
DPDZ
Why does the car jerk when I press or release the pedal? On injectors, the most common culprit is an unadjusted throttle position sensor. In this case, the ECU ( the electronic unit control) reacts to changes with a delay, and gives incorrect commands. That is why an incomprehensible jerking appears when the gas increases or decreases. Eliminate the cause by adjusting the sensor. After making the adjustment, you can forget about the problem for a long time.
For work, you will need a tester, with its help they call the sensor, and bring this entire system to the proper readings.
Poor quality fuel
Sometimes, these symptoms appear shortly after refueling. Here you can be congratulated, you have poured fuel containing a suspension of solid particles. Jerking appeared due to clogged filters, and possibly nozzles. To eliminate it, you will have to clean the entire fuel system. It will take quite a long time, but there is simply no other option. Remember the gas station where you refueled, and don't go there again.
In the worst case, your nozzles will clog. You can clean them yourself, without even removing them from the engine, but it will be much more effective to remove them and clean them at a special stand. In the very best case, poor quality fuel will contain water and will gradually be used up.
A malfunctioning electronic control unit often leads to jerking of the car. The reason is incorrect reading of readings, as well as incorrect commands. In this case, fuel injection is delayed. The problem can manifest itself not only when working with gas, but also in other modes. Computer diagnostics will display an “ECU error”.
The problem is treated by flashing the equipment. In severe cases, the entire unit may need to be replaced. If you do not deal with the elimination of the problem, then problems with increased consumption fuel and other troubles.
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Carburetor
On carburetor engines the reason may be a wedging of the throttle valve, as well as the throttle cable. This leads to incorrect vehicle power management. Usually it is enough to treat the choke with special substances and develop it. You can change the throttle cable at the same time. It may be rusty and preventing the throttle from opening / closing in a timely manner. Perhaps this is one of the simplest reasons for jerking a car when working with gas.
Ignition... Ignition problems can also cause bad behavior in the vehicle. Most often, this happens together with a general drop in engine power. If you experience twitching while driving, be sure to check the correct operation of this system. It is worth starting the check with the candles, if they give out a bad spark, then it makes sense to continue the check.
Sooner or later, every car enthusiast has to face the following problems:
- The appearance of malfunctions in the valves;
- Sharp jerks of the car (there is a feeling that it is twitching by itself);
- Lack of instant response of the engine to pressing the gas pedal.
Moreover, when you press the gas pedal, the car begins to twitch not only when idling, but also during acceleration and at full speed of the vehicle. To understand how this happens, what is the reason and what needs to be done to correct the situation, it is necessary to move from the symptoms to the causes of the breakdown.
The main reason for "jerking" the car when you press the gas pedal
The main cause is most often associated with an oxygen rich / depleted fuel mixture. It is because of the lack of air that the crankshaft continues to rotate despite the fact that the gas pedal has long been released. In addition, when the pedal is pressed sharply, the motor jerks and rotates in place.
The root cause of the problem is the preparation of the wrong mixture. In turn, the mixture can be supplied in different ratios due to a malfunction of other devices and components of both the motor and fuel system.
Twitching of the car due to a malfunction of the TPS
DPDZ is a special sensor that regulates the position of the throttle valve. It is quite simple to understand that the malfunction is connected with it - it starts to “jump” even when the accelerator is pressed smoothly. The jerking process is as follows:
- The throttle valve remains ajar for a long time;
- After that, when accelerating faulty sensor the position of the throttle valves with a delay transmits a signal to the on-board computer of the machine;
- As a result, the machine cannot quickly switch from idle to full speed in load mode, after which fuel is in large quantities and abruptly fed into the combustion chamber;
- The result is a sharp drop in pressure in the fuel rail design. The motor will first work in jerks, and then completely stall.
This type malfunctions can often be found in vehicles with injection engines. From this are not insured as domestic cars (Lada Priora, Lada Vesta Cross, Lada Granta), as well as models of foreign cars (for example, the same Ford Focus). The solution in this case is one - to go to a car service, where a faulty sensor will be replaced.
Advice: do not try to solve the problem yourself by repairing a faulty TPS. As a rule, after repair, a previously faulty mechanism can last no more than 1-2 months.
Twitching of the car due to a malfunction of the mass air flow sensor
The second sensor that affects the supply of air to the system is the device for adjusting the mass flow of oxygen in the system. It works in the injection type of motors and is responsible for supplying air during the formation fuel mixture... If this component is defective, then your car will also twitch, not even having time to accelerate. The solution is the same with the first sensor - dismantling and complete replacement DMRV.
Jerking the car - a malfunction in the carburetor chamber and pump
In case the motor starts to work with jerks in carburetor machines even with a weak pressure on the gas pedal, the focus should be on the carburetor chamber. The problem is often associated with clogged outlets that are located in the first of the carburetor chambers.
When the fuel enters the engine, it takes with it part of the burning and metal shavings, as a result of which the mixture undergoes changes, and the engine runs unstable. You can solve this problem yourself - just remove the carburetor and blow out all its pipes and openings with compressed air.
A classic example is the following situation: when replacing the front hub bearing with a VAZ-2109, the pump was damaged. As a result of failure of the accelerator pump of the carburetor, the mixture is supplied to the motor in an incomplete volume. The result is the appearance of jerks during even a smooth pulling off attempt. In most cases, it is impractical to repair pumps, which is why they are simply changed in a car service.
Twitching the car during acceleration
This problem can manifest itself with a smooth set of revolutions, which is accompanied by a sharp short jerking of the vehicle. In this case, the reason is associated with the lack of a constant flow of the fuel mixture into the float chamber of the motor. That is, the fuel is burned in the chamber much faster than fuel gas pump overtakes a new stream. As a rule, a breakdown can be found precisely in the design of a gas pump.
The solution to the fuel pump malfunction takes place in 3 stages:
- Remove the top cover of the pump and carefully examine the surface of the hole where the valve structure should be located;
- If the O-ring is abraded or missing, fix a new one;
- If, during the diagnosis, a chamber depressurization is detected or the problem is related to interruptions in fuel injection, then the final stage will be associated with a complete replacement of the inoperative valve and further restoration of the sealed state in the system.
Advice: when repairing, do not try to patch up holes in the old cylinder and reinstall it. This may further lead to overhaul the entire engine structure.
The appearance of jerks in the car with a sharp press on the gas
If the reason is not related to the gasoline pump, then these symptoms may indicate the so-called "triple" of the engine. In the machine, a situation arises in which only one of the 4 cylinders can work correctly. As a result of "triple formation", the motor simply cannot react in time to pressing the gas pedal, after which such problems arise. You can deal with the breakdown in the following ways:
- If the oxygen supply sensor is not working correctly, the system is diagnosed using a multimeter. In the event of a malfunction, it is simply replaced.
- If the valve timing in the motor is shifted, it is necessary, with the help of car service specialists, to adjust them according to the appropriate instructions.
- The detection of an incorrect glow plug number is solved by installing a new set with the correct number.
- The problem of clogged nozzles can only be solved in a car service. To do this, they are installed on a special stand that simulates the operation of a motor, and washed with a special solvent.
- Also, a problem can arise when the emulsion tube and well located in the construction of the second chamber are clogged. carburetor motor... The only solution here is to flush the carburetor and tube with kerosene.
Engine jerking due to problems with the ignition system
If, when the car picks up speed, you observe sharp drops in power, then the reason lies in the malfunction of the elements of the ignition system. This problem applies to any type of engine. The only correct solution is to check the ignition with the engine off. It is carried out by the following features:
- The tightness of fixing the blocks with wires is checked;
- Lack of chips and good condition of the coil;
- Serviceability of the wiring connecting the ignition system to the engine.
After checking all the elements, you need to start the car and just listen to how the engine began to work. If you find the appearance of characteristic clicks, then there are small high voltage breakdowns in the system. In this case, you will have to buy all the elements of the ignition system - a coil, a block and a set of high-voltage wires.
Advice: do not try to replace the wiring on the machine yourself. Only highly qualified specialists can correctly connect relays and fuses with the help of instructions and a diagram, after which the ignition system will not burn out. You can also check the wheels at the same time by comparing the readings in the tire pressure table of the car.
If the engine runs smoothly, the problem may lie in the spark plugs. And they ate to be more precise - in the absence or rare appearance of a spark. The presence of defects in the sparking system can be easily detected if the car engine starts to jerk when descending hills and even on flat road sections.
For example, the problem with a set of candles is typical for vehicles under nissan... This is due to the equipment of their engine model CA-18 with a special design contactless distributor... The distributor housing contains a switch, in the event of a malfunction of which the spark signal does not go to on-board computer, and such a specific movement of the machine occurs. It is possible to correct the jerks of the motor only with a complete replacement of the distributor components.
If the set of candles is in excellent condition, the only remaining reason can only be malfunctions in the operation of the control unit of the carburetor type of the motor. In this case, jerks do not occur constantly, but accidentally and only during a long car ride.
It is possible to detect faults in the control unit only after diagnostics in a car service at a special stand. Also, with the help of a lift, it will be possible to see that the car occasionally jerks at idle speed. As a result, the control unit (EFI) should be replaced along with the breakdowns found in other parts of the vehicle.
Your almost new car with an injection engine suddenly, for no apparent reason, began to twitch during acceleration? There can be many reasons for such a nuisance, but here we will consider mainly those related to work. injection engine... This type of engine has a number of significant advantages over a carburetor engine. But at the same time, it is structurally more complicated, therefore, the reasons for its malfunctions can be much greater. In particular, the "injector" has an electronic control unit ("electronic brains") that control fuel injection, focusing on the readings of various sensors (controllers) of the engine state. There are quite a few of these controllers, but jerking when accelerating the car can be, first of all, associated with a malfunction of the following ones:
- Throttle position sensor (TPS)
- Mass air flow sensor (DMRV)
- Crankshaft position sensor (DPKV)
Attention. The most unpleasant consequences can be caused by improper work, or - God forbid - DPKV refusal. In this case, the injector will stall, and you will not be able to start it in any way. Therefore, if you suspect that engine jerks are associated with DPKV, it is best to stop and check the operation of this sensor yourself.
To do this, to the exit of the DPKV (located at high tide oil pump) you need to connect a car oscilloscope and start the engine. With a working DPKV, clear pulses of the injector operation will be visible on the oscilloscope screen. If the impulses are blurred (or not visible at all), then it is better not to risk it and immediately get to the service station, where you can carry out computer diagnostics this and, if necessary, all other controllers. Such diagnostics can also reveal malfunctions in the operation of the oxygen sensor (lambda umbrella) or the electric valve of the injector, which are also common reason jerking the engine.
The second group of reasons for jerking in the engine is a malfunction in the injector ignition system. These include improper operation of the ignition module, as well as the spark plugs, ignition coil, and high voltage wires. therefore experienced drivers always have in stock a set of spark plugs and an ignition coil, which most often fail.
The last large group of reasons for the jerking of the car are various malfunctions of its fuel system, for example, irregular operation of the gas pump due to clogged fuel filters or formation air congestion in the fuel hoses. A specific malfunction of the injectors leading to jerks of the machine during acceleration is clogging fuel injectors... They, having very small holes, when using low-quality gasoline, are often clogged and require cleaning. This can be done independently, using the tips of specialists, but it is better to clean the nozzles with ultrasound at the service station.
A working car is a guarantee of traffic safety on the road. However, unexpected disruptions during movement can cause special troubles. Such problems include a situation when the car jerks during acceleration, or there are interruptions when driving at low speeds.
The best way to get rid of surprises is prevention and correct diagnosis. With their help, you can do without expensive repairs.
It is difficult to carry out diagnostics with an unevenly running car that is idling. The correct solution would be to identify interruptions during its movement. For this, a straight-line section of the road without heavy traffic is selected.
While driving, we turn on the gears one by one. At each included stage, we sharply depress the accelerator pedal. The power plant must be sensitive to all the efforts of the driver. In those cases, when the car jerks when you press the gas pedal or does it without any effort, then vehicle needs a closer inspection of individual nodes. It all depends on the specific behavior of the car.
Intermittent movement during acceleration
Problems of uneven movement during a high-speed maneuver most often lie in the unstable flow of fuel into the float chamber. Gasoline is generated faster than it enters it. The supply of liquid to the gasoline pump is carried out intermittently.
You need to solve the problem by opening the fuel pump cover. We carry out a visual inspection of the hole with the valve. The seal is often out of place. This lack of sealing leads to a complication in the supply of gasoline to the system, because of this, the car twitches while driving. The necessary operation is to replace the valve and resume tight operation. If there is a seal on hand, then you can do it yourself.
Unstable movement at low speed
Troubles occurring while driving at low speed are the result of incorrect operation of the injectors. The culprit is also often a loose bundle of wires, which can fray if rubbed against fuel pipes while driving.
Bare wires are shorted to tubes. In this case, the injectors are disabled, and the stability of the injection suffers. If wires are the culprit for the car twitching when driving at low speeds, then it is better to change the harness message. After replacement, you need to fix them on the body, to avoid the recurrence of the problem.
Instability is associated with pressing the accelerator
At a time when the driver "presses the gas", the car pulls, this may be due to the ineffective operation of the vacuum ignition angle regulator. This element is located in the distributor.
Since gasoline burns at the same speed, the driver seeks to increase the engine speed and presses the pedal, then the engine needs to be ignited faster air-fuel mixture... The work of the vacuum regulator begins just with an increase in speed above 1500-2000 rpm. Opening throttle at the same time, due to the resulting vacuum, it pulls back the bearing, which increases the ignition timing.
To diagnose the operation of the vacuum regulator, it is enough to remove the hose and seal it with your hand. You will hear how the suction effect works. When air enters inside, the vacuum is not formed, the tightness is broken, and when starting off, the car jerks.
Another culprit behind why the car jerks on the move is the accelerator pump spray. You can see the performance of the element after removing the diffusers. Then you need to press the lever and watch their work. Failure means that one of the unstable problems has been detected.
To repair the mechanism, you will need to dismantle it and remove the ball, clamping the lower side with pliers carefully so as not to deform the case. With the help of a compressor, we purge the channels and, having assembled it, we install it without gaps. The resulting gaps will lead to unwanted discharge. Correct operation and purge cleanliness is assessed by a long, straight jet.
A rare case with a diaphragm
A malfunction with the accelerator pump diaphragm is not detected so often. Only the spring remains in the structure, and its cover disappears. You have to make a homemade button from available tools. If such a problem is identified at the station, auto mechanics suggest completely changing the carburetor so as not to mess with trifles.
The culprit filters
When the car jerks when driving at low or high speeds, it is necessary to remember how long ago fuel filters... In diesel power plants, as a rule, put a pair: coarse and fine cleaning. The main trouble is the second.
Fuel filters
To identify the condition of the coarse filter, you can flip the fuel hose and blow through the mesh. In this case, the cap on the neck of the gas tank must be unscrewed. After a couple of days, we repeat the procedure. If the result is negative, you must take care of the cleanliness of the filter. fine cleaning... Almost all foreign cars use disposable fine fuel filters. The procedure for adding a small amount of fuel to the filter will help to add efficiency after replacing it.
A clogged fine filter leads to unstable engine operation, but this car does not twitch. The motor often stalls or suffocates.
Spark test
Some cars start to jerk when descending or on some level areas if there is a problem with contactless system ignition. A faulty switch located inside the structure can cause such consequences. Repair with this item is not carried out. You will have to completely replace the assembly.
Control unit monitoring
In some situations, car owners are advised to check the carburetor control unit. Characteristic feature the occurrence of tremors is their random occurrence or poor predictability. You can send the car to a diagnostic stand at the nearest car service. There you can detect instability at idle, the appearance of jolts when you press the accelerator pedal and the formation of "floating" revolutions.
Carburetor control unit
Often, for carburetor cars, the cause is identified in the carburetor control unit. It is practically impossible to independently diagnose this node "by ear" or by the consequences of the motor operation.
Conclusion
The emerging instability or intermittent operation of the car can in many cases be diagnosed and "cured" by yourself. This will cost significantly less than at the station. If you don't have enough experience, you can contact your friends or check several "suspicious" sites. You should not delay solving the problem, since such unstable work a car negatively affects other components and general safety while driving.
