Why does the car jerk?
There can be simply a huge number of problems due to which a car can drive jerkily (twitch), and they are individual for each car. These could be problems with the fuel system or transmission problems. Let's look at each of the reasons.
Fuel problems
Problems related to fuel supply to the engine.
Gasoline pump
All cars with injection engines are equipped with a fuel pump that pumps pressure into the fuel system. The normal operating pressure of the pump reaches 10 kg/cm³. Over time, the pump may lose its former power due to aging or dirty filters, fine and coarse fuel cleaning, which will undoubtedly lead to a loss of pressure and improper operation of the internal combustion engine.
Injectors
Another important indicator in the fuel system is the injectors. They spray fuel into the engine cylinder head, mixing it with air and feeding it into the combustion chamber. Over time, the injector nozzle becomes clogged with dirt and carbon deposits, which contributes to incorrect and even insufficient fuel atomization, which leads to uneven operation of the entire internal combustion engine.
Ignition problems
Problems associated with the formation of a spark in the engine.
Candles
To ignite the fuel mixture in a car, spark plugs are used, which produce sparks in the combustion chamber, thereby igniting the air-fuel mixture. Over time, due to the low quality of fuel, which is abundant in the vast expanses of the Russian Federation, spark plugs become covered with soot or, due to exposure to high temperatures, change their gap, which leads to improper operation of the internal combustion engine.
Wires
Spark plug wires also play an important role in engine operation; they transmit high voltage from the coil to the spark plug. The insulation of these wires is made of silicone and, under the influence of high temperatures and time, is subject to drying out and, consequently, cracks. High voltage, passing through a wire with a crack, can make its way to the body and thus does not even reach the spark plug, this is especially noticeable at high speeds and when the car is running under load.
Reels
The ignition module is the element that produces a spark to the cylinders; when it fails, the cylinders fail, but it often happens that the module can turn off due to temperature or load. By the way, the ignition module is no longer available in more modern cars; it was replaced by individual ignition coils, which helped get rid of wires and their problems. The IKZ is put directly on the spark plug and produces a spark for exactly one cylinder in which it is installed.
Transmission problems
Problems related to the gearbox, drives and wheels.
checkpoint
The gearbox is responsible for moving the car. Breakdowns are possible very often, especially if it is a rather complex automatic transmission, in which you have to frequently change the oil and monitor its quality. Failures in the gearbox can be in bearings, shafts, or clutches.
Drive
Car drives or cardans, which transmit rotation from the gearbox to the wheels, can also be the reason why the car jerks. Wear of constant velocity joints can create backlash between the gearbox and the wheel, which will lead to jerking. It’s the same with the cardan transmission, whether it’s on a crosspiece or a CV joint, its wear promises knocks and jerks.
Wheels
Wheels that have uneven wear, namely ellipse, can create jerks on the car when it moves at a certain speed, this is most noticeable on a flat road at a speed of 40 km/h.
Impact of jerks on the car
Whether jerking the car is beneficial or harmful is a rhetorical question. It’s the same as poking a person with a knife and asking if your health is improving. Any kind of jerking of the car is harmful, be it just a jolt when driving or a consequence of changing gears.
The main impact falls on the transmission unit and the engine part. First of all, the load on moving elements (bearings, switches, gears) increases. Each impact can deform, leave a crack or completely break any of these elements. Repairs can take a long time and cost the car owner a significant amount of money. That is why it is important to initially determine the reason why the car began to twitch and eradicate it.
Why does the car engine shake during warm-up, and how to fix it?
Warming up the vehicle. This topic is as old as the World. Go to any car forum, and you will see that there are a lot of people writing about how their car behaves strangely while warming up. This article will also talk about warming up the engine, or more precisely about why it shakes for the first minute after turning on the ignition.
Every person who knows at least a little about cars knows that on a fully functional engine, the tachometer needle should lie at the lowest extreme point and not move. At the same time, the power unit should not make any extraneous sounds. But it happens that during normal warm-up the engine jerks. This lasts from 30 seconds to one minute.
It would seem that it won’t last long, and therefore there is no need to worry. But in reality, this causes tension for the owner of the vehicle. As practice shows, owners of cars produced by the Volkswagen concern face this problem more often than others.
What is the reason?
If you go to a service station with such a problem, don’t be surprised if you have problems with sensors that didn’t exist before, and the lambda zone starts to act up. The worst thing is that some craftsmen will offer to overhaul the entire engine. If you are gullible, it is possible that you will “get” an impressive amount. And everything would be fine, but this money will be thrown into the air. The bottom line is that today, unstable engine operation during warm-up is an absolutely normal phenomenon. So, if you come to the service center and the mechanic starts telling you that he can solve this problem, know that this person does not follow modern trends in the automotive industry.
And yet, why does the engine tremble? First, a few words about the catalyst. What does he have to do with it? Surely many people thought exactly that now.
Who doesn’t know, a catalyst is needed so that exhaust gases enter the atmosphere, being purified of harmful impurities. The peculiarity of this device is that for it to work properly it must be well warmed up. When the engine starts after parking, it is cold. Consequently, the exhaust will not be clean. This information is sent to the electronic control unit, and it tries to warm up the catalyst as quickly as possible. What is accelerated heating of the internal combustion engine? This is the arrival of an over-enriched fuel mixture.
If we explain everything written above in more understandable language, then a lot of fuel (in excess) flows into the engine in the first seconds of operation. Due to this, the exhaust temperature becomes higher with each crankshaft revolution. As a result, the catalyst reaches its optimal temperature faster.
This whole process takes just 30-60 seconds. This is exactly how long the engine will twitch and make strange sounds until the required temperature is reached for the catalyst to fully function.
That's all. If your car's engine jerks after starting, don't worry - there's nothing wrong with the car!
But there is another point: catalysts are usually “removed” from used cars. Supposedly there are valuable metals there.
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The car jerks due to faults in the manual transmission
For normal movement of a car with a manual transmission, constant gear shifting is required. The main rule of manual cars is to switch the lever on the box in time and correctly. If you violate the sequence, you can quickly wear out the parts and simply bring the car in for repairs.
In the case of a manual transmission, when changing gears, the car jerks due to the actions of the driver. What should you not do if you are still driving a manual car? First of all, it is necessary to choose the right time to press the clutch pedal and change gears. Do not delay the transition to high gears, and after switching to it, avoid sharp pressure on the gas pedal. The most important thing is that there is no need to press the pedals randomly at speed; every action should be thought through or you will cause damage to your car.
Fighting jerking when the engine warms up. Overcame!
For those who like to read.
I didn't take any photos, just one screenshot. A little background history, those who read my posts will remember. After some time had passed after installing the HBO (Lovato 4th generation), minor problems began. The engine started well, ran steadily, but when warming up to the temperature of switching from gasoline to gas, the car jerked very often, namely: - jerked when driving in 1-3 gears, sometimes in 4th with an almost fully warmed-up engine; — during engine braking and smooth acceleration after braking; - on a rough road. After some thought and meetings with members of the forum and gas workers, it was decided to change the spark plugs, with no results! I changed the high-voltage wires, there is a result, the car began to drive a little smoother, but the jerking remained. I went to the LPG adjusters and thought it was the problem. We skated with them for several kilometers, adjusted them a little, but otherwise they said that everything was in order. I changed the IAC, no result! Then the car began to jerk on gasoline, before switching to gas. Let me remind you. that when the engine was warm, everything was fine. After one day, stopping at an intersection, my revs froze at around 1700, I realized that I needed to change the TPS. I bought a Contactless TPS from the manufacturer VTN (its price is 80 UAH), installed it and lo and behold. The car just came to life, no twitching, not even before switching to gas. nor after. My joy knew no bounds. But, as it turned out, not for long. After several days of calm, she began to twitch again, and even worse than before. It was impossible to drive without squeezing the clutch, until the engine was almost completely warmed up, in 1st-4th gears (I just didn’t try it in 5th), on gasoline and on gas. After reading Drav2.ru again, the idea came to me to check the twists (crimps) on the wiring harness under the hood. I would like to immediately say thank you to suro1975 and Hapson for the blog entries. I got rid of the “floating” engine speed and soldered the twists, respectively, which helped me. Naturally, before you climb into the harness itself with the engine running, you need to shake it a little. In my case, at the slightest touch to it, the speed dropped and the car almost stalled. sometimes they increased, sometimes they hung at higher levels than XX. For clarity, I took a screenshot that shows how the voltage on the TPS fluctuates when the wiring harness moves
at the same time, neither the gas pedal nor the throttle valve were touched, the car was idling. What I managed to notice was that the voltage dropped from normal 0.63V to 0.61V and rose briefly to 0.71V. The reason has been found - you need to solder. I had 3 crimps, all of them, as they say, are in good condition, not oxidized, but the fact is a fact. One crimp goes to the air temperature sensor, the second goes to our all-favorite TPS, which apparently was the problem. I won’t describe the process itself, because... The comrades I mentioned above did all this perfectly before me. And I didn’t take any photos, because the process started after 19:10 and I wanted to do everything in one evening. And my hopes came true. at 21:20 I was already home. I soldered everything, heat-shrinked it, and insulated it. Now like new. Test run the engine - everything works. We pull the wiring harness - everything is stable. no failures. My joy knew no bounds. We are finally collecting. Today I went to work, no failures, everything works like a clock, I didn’t even notice the switch from gasoline to gas. Speed picks up smoothly. The car does not jerk on potholes. Business for 2 hours, but so much joy. It’s good that I didn’t have time to change the ignition module. When searching for the problem, I was confused by the fact that it appeared less than a month after the installation of the HBO, which is why I blamed it. But everything turned out to be banally simple. For HBO, one wire is also soldered into this harness, and apparently during installation, after moving the harness itself a little, this problem surfaced in almost all Lanos, especially. that the car is not new. And another joyful moment in which I realized that I was not mistaken with the LPG installers. The wire they connected was securely soldered and not twisted. not crimped. and soldered as expected. This is the first case of normal installation of wires in my car at a service station. All the others that I discovered after buying the car were simply twisted, even on the radio. Thanks to the previous owner, apparently it was serviced at “good” service stations. For anyone who has similar problems, I recommend checking it out and, if necessary, doing exactly the same procedure.
Thanks to all! Not a nail. not a rod!
Cleaning the injector.
First, of course, you should check the spark plugs, however, if the car starts normally and jerks when driving hot, the problem is most likely not in them, but in the injection system. First, let's look at the stages of clogging of the mechanism, there are three in total:
- At this stage you will not notice any changes. When hot, the car runs perfectly, does not jerk and there seems to be no problems with the engine, which so far starts normally. Typically, this stage almost always progresses into the next one.
- While the car still does not jerk when driving, but the engine is not very stable when hot, small adjustments are possible; gasoline consumption also increases, the car sneezes when it starts.
- The last stage, it is no longer possible not to notice it. The car jerks noticeably when driving, warming up does not help, and the engine also runs disgustingly when hot. If you don't take care of the injector at this stage. Very soon, your car's engine will require more serious and expensive repairs.
Methods for flushing the injector
If you are not a professional auto mechanic, you should not even think about flushing the injector yourself. Otherwise, the car will not only stop jerking when hot, but will not start or drive at all.
However, one way or another, theoretical knowledge in the field of cleaning the injection mechanism will still not hurt. Having familiarized yourself with the theory and seen in practice how masters do this procedure, next time you will cope with it yourself.
Liquid flushing
So, first on the list is liquid cleaning of the injection mechanism. In this case, the car starts, however, the fuel supply is disconnected. Instead of a fuel supply hose, a special flushing system is connected to the engine, which supplies fluid to the injectors. The washing procedure in this case is carried out, as they say, hot.
It is important that in this case the washing does not get into the gas tank, otherwise it will dissolve deposits on the machines. As a result, the fuel filter and pump will become clogged and will need to be replaced.
As for the choice of fluid, it all depends on the age of the car and the degree of contamination of the injection mechanism. The ideal option is to entrust the choice of washing to professionals. Those who are faced with cleaning the injector every day will be able to choose exactly the composition that will not harm the engine. In general, ideally, maintenance in the form of such a liquid flush is recommended for all relatively new cars every 30 thousand kilometers.
Ultrasonic cleaning
A more powerful alternative to liquid is ultrasonic engine flushing. In this case, the nozzles are dismantled and placed in an ultrasonic device. Next, all that remains is to set the required washing time, everything else will happen automatically. The device itself for ultrasonic cleaning of the injector is quite expensive, and you can only find it in a good service. The main thing is that the washing in this case is carried out by a professional. If you choose the wrong time, the injector will be damaged and the car will not only stop jerking when hot, but also stop starting.
What to choose
There shouldn’t be any problems with choosing when it comes to cleaning the injector. It all depends solely on the age and general condition of the car. If there are no serious problems - the car does not jerk, starts well, and the engine runs stably when hot, choose flushing with liquid chemicals. You can deal with the first and second stages of contamination in this way without any problems.
If the car jerks, then it’s time to resort to heavy artillery in the form of ultrasonic washing. However, first it is necessary to carry out qualified diagnostics of the car and exclude other causes of unstable engine operation when hot.
For example, spark plugs or idle speed sensor. In approximately 90% of cases, the problem, as it turns out, is precisely these spare parts, and flushing the injector is not necessary at all. How to perform diagnostics is described in detail above.
What's the result?
As you can see, at the initial stage of diagnosis, if the engine twitches at idle, you should start with the simplest:
- check spark plugs and high-voltage wires;
- assess the condition of the air and fuel filter;
- if the car has a carburetor, clean and adjust the carburetor;
- on the injector, check and wash the nozzles;
- perform computer diagnostics of the engine;
If the diesel engine jerks at idle, then problems with the injection pump should also be added to the general list of possible problems. The pump has many moving elements, damage to which or clogging can also lead to jerking or obvious tripping in the cylinders.
Why might the engine vibrate at idle? Causes of malfunction, diagnostics. Tips and recommendations for reducing engine vibration levels.
