The engine does not respond to the gas pedal reasons

Author: Fon_Enot

07 October 2022 00:56

Community: Autoworld

Tags: speed cars cars gasoline car diagnostics motors why speed

133510

There are many reasons why a car accelerates poorly. An experienced car enthusiast knows the features of his car well, immediately notices a drop in power and begins to look for the reasons.

Source:

Any engine loses a little power during operation. But even on engines with high mileage, the loss is on average about 10% of the declared value and the driver hardly notices it. But, if the car begins to accelerate poorly, engine traction is lost, the engine loses throttle response when you press the gas pedal, it becomes difficult to operate the vehicle. This problem requires diagnosis and solution. Sometimes the reason for the loss of overclocking power can be very simple. Like, for example, from one of the car forum participants: “I bought an excellent car of the **** brand (station wagon) 2012. V=2l, automatic. The gas pedal is a little tight when you press it to the floor - there is no acceleration dynamics. It feels like it’s not 2L, but 1.6-1.8L. Before that I drove the same one, only a sedan - it is much faster. What could be the reason? Or is this normal for a station wagon? In response, he receives a shocking confession: “Once, when overtaking, I also encountered the fact that the dynamics had disappeared. It turned out that the MAT was rubber, it was like that, it folded in half under the pedal. I unfolded it - and everything was in order.” A couple of hours later, on the same forum, the owner of a new car made a revelation: “Beautiful! I think, let me really take a look - maybe a rug? I looked into the interior, and there was actually a RUG ***** stuck under the pedal! Corrected it and flew 150 km/h. Bliss! THANK YOU))))". Let's be happy for those who were able to fix the problem in such a simple way. For those who pick up speed slowly and the mat has nothing to do with it, we’ll tell you what other reasons there could be.

Doesn't respond to the gas pedal.

Today, while driving, the gas pedal stopped responding, the idle is stable, I press the gas zero, the check is not lit, I removed the chip from the throttle sensor - it stalled, I removed the chip from the throttle sensor, nothing happened, but I drove a little with the throttle on - above 2000 rpm. Doesn't rise in gear. then he got up again and threw on a chip - nothing. You can keep the Gasoul for at least an hour, nothing, idle is normal. I changed the injectors not so long ago, the spark plugs and wires too, the fuel pump too. The car is 2004, 8 valves. I drove for 4 hours on the clutch. Can anyone tell me where to look for the problem?

to Sargofak:

Judging by the year of manufacture (in the profile), unless there is a mistake, “you” should not have an electronic throttle assembly.

to *AutodeD: definitely not electronic

In this case, if the throttle is mechanically controlled by a pedal, measure the fuel pressure.

to *AutodeD:

I'll measure it tomorrow, I didn't have time today. In the morning, by the way, it barely started, min. 15 with 400 rpm pedal. It just held it, and when it warmed up it held it stably. I changed the ignition module to a heap (it was in stock), the xx sensor, the d sensor, the filter and it was of no use. In short, when it’s cold, it won’t start with great difficulty. Tomorrow I will measure the pressure and check the DMV (the donor will arrive).

Check the strainer on the fuel pump.

to Alexandert:

Today I took out the pump, and of course there was a little dirt. blew, washed, installed.

Today I spent the whole day tinkering with the car, measured the pressure (normal), took out the pump again and cleaned the mesh. Then I looked at the marks, which seemed to be normal, but decided to look again at the crankshaft pulley (with the alternator belt) and lo and behold, I saw that the key had been cut off and the pulley had moved (due to you couldn’t see the mud) in less than 15 minutes and everything was fine. Thank you all for your help.

Thanks for telling me the reason. We can safely say that we got off lightly.

Salam to everyone, this problem is that the car does not respond to the gas pedal. It holds idle speed normally, but as soon as you press the gas pedal it seems to choke, but at the same time it doesn’t develop any speed at all. check light is on. then some time passes, you accelerate normally and then everything repeats again VAZ 21 10 99

This may be a stupid question, but I'll ask it anyway. Why does the check light come on? What mistake?

PS Actually, there is a thread on 2114, a dozen in the next branch.

Yes, I would never have thought of that

Then it's not the throttle, but the throttle position sensor. Does the check light come on? What did the diagnostics say about the errors?

to 92serega9229:

Looks like an electrical glitch. You can try adapting the pedal. And maybe you remember that they didn’t change anything electrically ahead of time?

The pedal sensor potentiometers have died. Replace the entire pedal.

Maybe. This is a feedback system, everything is tied to the ECU, one cannot exist without the other.

Reasons why a car may jerk while driving

This section lists all the most common reasons why a car shakes and jerks while driving. For convenience, potential malfunctions are divided depending on the fuel used and the mixture formation system. This will allow you to quickly determine why a car with a carburetor, injector, diesel engine, or equipped with gas equipment jerks while driving, or at least eliminate possible problems.

Why the car jerks while driving: reasons for different types of internal combustion engines

Causes	Why does it twitch while walking?
Causes	Injector	Carburetor	On gas	Diesel
Carburetor malfunction or blockage	✘	✔	✘	✘
Clogged air or fuel filter	✔	✔	✔	✔
Gas filter clogged	✘	✘	✔	✘
Clogged or worn injectors	✔	✘	✔	✔
Problems with spark plugs, coils or spark wires	✔	✔	✔	✘
Air leak into the intake manifold	✔	✔	✔	✔
Malfunction of TPS (throttle position sensor) or throttle actuator***	✔	✘	✔	✘
Malfunction of sensors: accelerator, IAC (idle air control), MAF (mass air flow sensor), DTOZH (coolant temperature sensor), MAP (absolute pressure sensor)	✔	✘	✔	✔*
Malfunction or poor contact of the crankshaft sensor (crankshaft sensor)	✔	✘/✔****	✔	✔*
Fuel pump malfunction	✔	✔	✘	✘
Faulty injection pump (high pressure fuel pump)	✘/✔**	✘	✘/✔**	✔
Gas reducer is faulty	✘	✘	✔/✘**	✘
Freezing of the gearbox or lines	✘	✘	✔	✘
Worn or incorrectly adjusted clutch	✔	✔	✔	✔
Incorrect operation of the gearbox	✔	✔	✔	✔
Wear of the CPG, malfunction of valves and hydraulic compensators	✔	✔	✔	✔
Low quality or unsuitable fuel	✔	✔	✔	✔

* relevant only for diesel engines with a common rail injection system and similar ** relevant only for cars with direct injection and for 6th generation LPG systems for them, injecting liquid gas *** relevant for injection cars with an electronic pedal (e-gas) * *** relevant for carburetor cars with an electronic (contactless, microprocessor) ignition system

Diagnostics of modern cars is simplified by the presence of an ECU. If the car jerks while driving and the check engine light is on, basic computer diagnostics using OBD II will indicate the reason with a high degree of success. However, the indicator does not light up in case of any problems.

Finding out why a car with a carburetor jerks while driving can only be done by inspecting and checking potential locations of the problem.

The main reasons why a car jerks when driving: video

In cars running on gas or diesel fuel, much depends on the generation and features of the supply system.

In addition to the type of fuel and power system, the problem of the malfunction depends on the conditions under which the car begins to twitch:

when moving forward at low speeds;
when moving backwards;
when picking up speed;
when driving at a constant speed.

Why does the car jerk when driving in different modes?

Some malfunctions that lead to jerking appear only in certain driving modes, these include:

Clogged or worn injectors . The injectors (on the injector, LPG 4+ generation and on the diesel engine) do not spray fuel correctly, which leads to worse ignition of the fuel assemblies, causing the engine to operate unstably and lose traction. To eliminate the problem, you need to wash the injectors or replace them.
Carburetor clogged . Due to clogged jets, mixture formation is disrupted. To fix the problem, you need to flush the carburetor and flush the fuel line.
Clogged fuel filters . Clogging of gasoline, diesel or gas filters leads to a decrease in the throughput of the fuel line. The solution to the problem is to replace the fuel filter.

New and broken crankshaft position sensor

The throttle position sensor fails when the contacts are worn out.

Checking the coolant sensor with a multimeter

Fuel pump malfunction . A decrease in fuel pump performance leads to interruptions in fuel supply. The problem usually progresses with load: at idle it is weakly expressed, and when accelerating the engine openly jerks and stalls. To check the pump on an injection car, you need to measure the pressure in the fuel rail with a pressure gauge, on a carburetor - after the pump, on a diesel engine - at the outlet of the injection pump.
DPKV malfunction . The crankshaft sensor determines the moment at which fuel must be supplied (and a spark - on gasoline / gas). It itself rarely fails, but if there are problems with the wiring, the signal is lost, the engine stalls, but starts up by inertia, which causes jerking and shaking.
DTOZH malfunction . Modern internal combustion engines with an injection system (both gasoline/gas and Common Rail diesel) adjust the fuel supply and ignition based on the engine temperature. If the DTOZH is faulty, then the injection dose, ignition angles (gasoline, gas) or injection timing (diesel) will not correspond to real conditions, which is why the engine begins to operate unstably and loses power. The DTOZ is checked using computer diagnostics or a multimeter (you need to find a temperature resistance table).

Diagnostics of the TPS sensor: video

Malfunction of the TPS or accelerator sensor . If the throttle position sensor or gas pedal is worn out (usually the potentiometer tracks are erased), the signal begins to “float”, which causes incorrect control of the remote control. To check the sensor, you need to measure the change in its voltage as you smoothly press the gas pedal (through diagnostics or with a multimeter). If sudden jumps or dips in voltage occur, you need to change the throttle or pedal sensor.
Ignition problems . If the spark plugs, their coils or wires are worn out, misfires occur. In the early stages, the problem can only appear at idle, since at high speeds these gaps are partially compensated by inertial forces and are masked. To diagnose, you need to inspect the spark plugs, coils, and wires for breakdowns (sparks in the dark). You need to check the spark plugs, wires, coils, and after finding the culprit, replace the faulty elements.
Air leak . If there is unwanted air leakage, the engine cannot properly dose fuel assemblies, the mixture becomes lean, traction is lost and jerking occurs. On carburetor engines with vacuum ignition control (and carburetor control, as, for example, on old Mercedes), the pumping ratio and gasoline supply are also disrupted. To find the location of the leak, you need to check the intake with a smoke generator. The main areas where air can leak are pipes and their clamps, carburetor flanges, throttle bodies, manifolds, receivers, and injector seals.
Off-season fuel . The problem is typical for diesel engines and gas. Summer diesel fuel becomes waxy in winter and clogs the lines, so the engine either does not start at all, or starts with difficulty and runs poorly. The summer propane-butane mixture (with a predominance of butanes) behaves similarly in winter, which evaporates poorly in cold weather. To fix the problem, you need to defrost the diesel fuel and refuel according to the season. It’s more difficult with gas, since to refill you need to first drain some of the gas, taking precautions (it’s better to visit a gas service station).
Bad fuel . If gasoline, gas or diesel is counterfeit, of low quality, or the octane/cetane number does not match the required one, the fuel will ignite and burn worse. Driving on such fuel is fraught with problems in the internal combustion engine and exhaust system, so you need to drain it, flush the fuel system and refuel with high-quality fuel.

Checking the mass air flow sensor using a multimeter

The absolute pressure sensor requires periodic cleaning

DBP malfunction . If the absolute pressure sensor used in gasoline engines without a mass air flow sensor and on the 4th generation LPG does not operate correctly, the composition of the air-fuel mixture is disrupted. You need to check the DBP, and if it is faulty, replace it.
DMRV malfunction . A faulty mass air flow sensor provides incorrect data on the amount of air entering the intake manifold, causing the ECU to dose fuel incorrectly. You can check the mass air flow sensor by measuring its voltage (with a multimeter or through diagnostics) when idle. For example, for injection VAZs, a voltage of less than 1 V indicates the ideal condition of the flow meter, from 1 to 1.02 - normal, from 1.03 to 1.05 - signs of wear, and more than 1.05 V - critical wear.
Wear of the CPG, malfunction of valves and hydraulic compensators . If the engine is badly worn, the valves are burnt out or the valves are set unevenly, compression drops. As a result, the reason why the car jerks at idle is weak and uneven pressure in different cylinders. The moments of force created by the pistons differ from each other, and this causes shaking. To check, you need to measure the pressure in the cylinders; it should differ between “boilers” by no more than 1 atm. Incorrectly set gaps must be adjusted, faulty hydraulic compensators must be replaced. Burnt-out valves and pistons will have to be replaced by removing the head, and if the cylinders are worn out, the entire internal combustion engine will have to be overhauled.

Below we will look in detail at the reasons why a car jerks while driving, what causes shaking at idle, and what can cause jerking when moving slowly.

All problems with sensors described here and below require checking both the sensors themselves and their wiring. Sometimes a working part does not work correctly due to poor contact, oxidation of terminals, rubbing of insulation, broken wires and other similar problems. Therefore, before buying a new sensor, inspect the connectors and check the wires with a multimeter!

Why does the car jerk when idling?

If the car jerks when idling, but behaves normally when the pedal is pressed, problems with the fuel supply system can be ruled out. They usually appear just when more fuel is needed. The most common malfunctions that cause jerking on idle are:

The car jerks at idle, finding and solving the problem: video

IAC malfunction . On injection cars, air is admitted when the throttle is closed through a bypass channel (bypass), the throughput of which is regulated by the idle air regulator. If it is faulty or the channel is clogged, air will not be supplied correctly, the motor will begin to twitch and trip. If the car jerks at idle due to IAC, you need to replace it to fix the problem.
Incorrect XX setting on the carburetor . On the carburetor, the idle speed is controlled by screws for the quantity and quality of the mixture, if the position is incorrect, the engine may adjust. The problem can be resolved by adjusting the position of the screws.
Clogged jet XX . In addition to the screw adjustment, the supply of fuel assemblies at idle speed is regulated by a separate jet, which, when clogged, supplies insufficient fuel. To fix the problem, you need to clean the jet, and preferably the entire carburetor.
Incorrect gearbox setting . In HBO systems up to the 3rd generation, the idle speed is adjusted with a separate screw that regulates the gas supply bypassing the membrane. If it is positioned incorrectly, the gas dosage will be disrupted. To eliminate the problem, you need to adjust the fuel until engine operation stabilizes.
Early inclusion of gas . On engines with gas equipment that have automatic fuel switching (based on engine speed or temperature sensor), shaking and tripping at idle may be a consequence of switching to gas before the gearbox warms up. In such cases, the lines or the gearbox itself freeze up, the gas supply slows down, and the engine “starves”. To avoid tripping, you need to switch to HBO when the engine temperature reaches +40-50 degrees or more. On GBOs of the 2nd and 3rd generations, in order to avoid early transition and freezing, you should not use too much gas until the internal combustion engine warms up, and on GBOs of the 4th and 5th generations, you need to check and, if necessary, adjust the temperature in the GBO controller.

If there are no problems at idle, but the car jerks while driving, the following sections will help you understand the reason.

The car jerks when driving at low speeds

If the car moves jerkily or the car starts to twitch at low speeds while driving, the reasons may be the following:

What is the reason when a car jerks while moving at low speeds: video

Wear of drive joints . If the car jerks when starting to move, the cause may be wear on the CV joints, if accompanied by a characteristic crunch, or a malfunction of the cardan crosspieces. Excessive play in the hinges generates shock loads in the transmission, which is why the jerk occurs. You can check the parts for play by driving the car onto a pit or a lift and turning the drive shafts or cardan by hand.
Throttle clogged . A dirty throttle does not allow enough air to pass through at a small opening, which is why the mixture is dosed incorrectly, the engine runs worse and the car jerks when driving at low speeds. The valve is checked visually, and if there are deposits, it must be washed with carburetor and throttle valve cleaner.
Incorrect setting of HBO . Incorrectly adjusted gas equipment (for example, an overtightened membrane on the HBO-2) may not add fuel or overfill fuel at low speed. Correct diagnostics of gas equipment of the 4th generation and newer is computer-based; for older systems, gas analysis using ShDK.
Problems with automatic transmission . If the torque converter box kicks and the car jerks at low speed, you need to diagnose the gearbox and its torque converter (“donut”). Most often, the cause lies in a lack of oil pressure caused by low lubrication levels or pump wear. First you need to measure the oil level and assess its condition. If the lubricant is in order, disassembly and troubleshooting of the box will be required.
Clutch slipping . When driving under tension in a car with a manual or manual transmission, a worn or overtightened clutch is overloaded. If at some point it becomes easier for the motor to turn the disk than the wheels, a jerk occurs. You can check the clutch by sharp acceleration. In addition, its slipping is usually accompanied by the characteristic smell of a burnt clutch.
The throttle actuator is faulty . On a car with an E-gas system, the throttle valve is controlled by the ECU using an electric drive, the malfunction of which leads to its insufficient opening. You can check the throttle assembly visually by assessing its opening depending on the position of the gas pedal.
Brakes jamming . If the brake pads grab the discs (this happens due to clogged circuits, pinched tubes, skewed caliper guides and other problems), the motor has to overcome additional resistance. This is what causes the jerking. Usually the problem is accompanied by a deterioration in the braking properties of the car (increased braking distance) and overheating of the discs/drums with pads. Since the discs and pads warm up at speed, inertia builds up - the jerking goes away, but the car slows down worse.

Car jerks when reversing

If the car jerks when you engage reverse gear, this is mainly due to problems with the gearbox, and four main reasons can be identified:

Typical wear of the reverse gear in a manual transmission

Automatic transmission overheating . In an overheated gearbox, the oil loses its viscosity and becomes thinner, which disrupts the operation of the gearbox. Reverse speed is one of the first to suffer from this.
Lack of automatic transmission oil . If the oil level in the gearbox is insufficient, jerking is also possible when the rear gearbox is engaged.
Automatic transmission malfunction . Malfunctions and blockages of the valve body, solenoids, oil pump or clutches cause jerking when reversing. Breakdowns can be identified during troubleshooting, since without disassembling “by eye” it is almost impossible to find the cause.
Wear of the manual transmission reverse gear . The rear gear of most manual transmissions is unsynchronized, so when used frequently, it wears out much faster than the front ones. In straight-toothed pairs, the teeth wear down (just like on the starter ring), which is why the gears can slip and the car jerks when reversing.

The car jerks when driving when accelerating

When accelerating, the car jerks mainly for the following reasons:

Wiring problems . When accelerating hard, the motor deflects (especially if the mounts are worn), which can cause contacts to come loose from sensors and other electrical components. On the injector it is necessary to carry out diagnostics and clean the contacts, eliminate breaks or short circuits, and replace damaged connectors.
Clogged air or fuel filter . If the filters are slightly clogged, the lack of air or fuel only manifests itself under load and at high speeds.

Connecting a pressure gauge to the fuel rail to measure pressure in the fuel system

Problems with the fuel pump . Lack of fuel pressure is a common reason why a car jerks when you press the gas. If the fuel pump or fuel injection pump is slightly worn, it is still capable of developing the required fuel supply pressure at idle, but cannot cope under load, the engine is “starving” and cannot develop its designed power. Pumps are checked by measuring pressure.
Blockage or malfunction of the second chamber of the carburetor . The second chamber of the carburetor is usually responsible for powering the engine under load. If it is clogged, incorrectly adjusted or faulty (for example, a wedge or a broken damper rod), it cannot supply gasoline vapor in the required quantity.
“Strangled” or incorrectly selected HBO . An incorrectly configured gas system (often inexperienced drivers and tuners do this to save gas) or an insufficiently efficient gearbox (for example, a 140 hp gearbox on a 120–130 hp engine) behaves in the same way as an incorrectly functioning carburetor or injector. At peak loads there is not enough gas, which is why the car jerks when driving when accelerating. Systems of the 4th generation and newer are diagnosed using a computer method, older ones - by adjustment by ear or (which is better) gas analysis with ShDK.

Sometimes the car jerks at high speeds when starting or accelerating due to low fuel levels. Since the fuel in the tank or cylinder flows back by inertia, the fuel intake can become exposed and capture vapor instead of liquid, causing a drop in pressure!

Gaps during acceleration

When accelerating a car, the load on the engine increases, which requires more fuel-air mixture, so most problems that cause failure during acceleration are associated with a lack of fuel or air. Check the condition of the fuel pump, filters, rail pressure, spark quality (in a gasoline engine). Changing the settings - mixture quality and ignition timing - is controlled by the electronics, so it is better to start diagnosing the problem by checking the dynamic indicators with a scanner directly during the trip.

When you press the gas pedal hard, used cars often experience a delay in the opening of the intake manifold flaps. This is a purely mechanical problem when, due to age and vigorous use, the collector becomes overgrown from the inside with a thick layer of soot “spitted out” by the cylinders of oil (and soot from the USR). The swirl flaps in the intake manifold can be cleaned or removed, just like the USR valve, but this must be done physically and programmatically, in a certified service center.

Why is it stupid? Basic faults

Type of VAZ-2112 engine

There are not many reasons for the effect when the 16-valve engine on the VAZ-2112 16 valves stalls. Of course, you will have to tinker a little in order to find the true reason in one case or another, but otherwise there is a direct road to a car service center. For those who have decided to repair their car themselves, this information will be useful.

So, let's look at the main reasons for this effect:

The problem is in the fuel system.
The crankshaft sensor has failed.
We clean the sensor from dirt and dismantle it.
Poor quality fuel.
The problem is the throttle.
Ignition fails.
ECU errors.

The main reasons are considered, and you can move on to solving these problems.

Methods for solving the problem

To eliminate failure during overclocking, you need to check all the components listed below step by step. This is a considerable amount of work, but the car enthusiast will be able to save a sufficient amount of money, which would have been charged to him at a car service center. Of course, for those who don’t understand the design of a car, that’s the way to go, or ask your friends who will fix the problems for half the price. But, if you follow the instructions, you can figure it out yourself.

Poor quality fuel

Poor quality fuel is a common cause of engine breakdowns

Of course, in our country, low-quality fuel causes many misfortunes and troubles for motorists. It is not possible to check the fuel at a gas station, so everyone is already struggling with the consequences. The only thing that can be done is to carry out regular diagnostics and cleaning of the fuel system.

Fuel system

Injectors on the fuel rail removed from the engine

The first line of engine protection is fuel filters, which sometimes fail and not enough fuel gets into the engine. On the other hand, when completely clogged, the injectors are clogged, which at low speeds give a normal amount of mixture, but if the engine is accelerated, the amount of mixture remains the same and a failure appears at low speeds.

The way out of the situation is to replace the fuel filter, clean or replace the gasoline pump mesh, and diagnose and replace failed injectors. The latter usually go through a cleaning stage, but this does not always help and they have to be replaced.

Throttle valve

Cleaned throttle body

A stuck throttle valve and insufficient air supply can cause the engine to become sluggish when accelerating. This is due to a non-optimal fuel mixture. In this case, the solution to the problem is cleaning.

Ignition system

High voltage wires of the ignition system

Another reason that the car began to stall while accelerating could be interruptions in the ignition. So, it is necessary to check the spark plugs and high-voltage wires where breakdowns could occur. If necessary, damaged parts must be replaced. The manufacturer recommends replacing everything in sets.

ECU errors

List of electronic control unit errors

The last problem is that errors occur in the electronic engine control unit. If there is a large accumulation of errors, this can affect the operation of various vehicle systems. Therefore, as practice shows, resetting ECU errors leads to normalization of the operation of the power unit.

There are a great many reasons for the strange behavior of a car during acceleration, all of them are different in their nature of manifestation and complexity of elimination. They have one thing in common: they are all associated with malfunctions in very important parts and components of your machine, so you should find out the cause of this problem as quickly as possible and eliminate it.

What did I do

I did not self-medicate, because, as experience shows, this is a waste of money in the absence of a convincing positive effect.

I did computer diagnostics, according to the results of which long-term fuel corrections were in the positive: the engine does not have enough fuel-air mixture. The control unit compensated for this deficiency by increasing the opening time of the injectors, so the car “stuck” at the start. The MAF sensor readings were low, indicating that the air filter was dirty.
I changed the air filter because it had become clogged during my summer travels.
My spark plugs are excellent, there is no carbon deposits. Despite my creativity, I do not change the brand of fuel station; I try, as they say, not to look for good from good.
I changed the fuel filter, and not just changed it, I flushed the fuel system. Previously, I did this procedure once a year on all my cars, I always liked the way the car was after it - playful and responsive, reacting to the gas pedal immediately when pressed.

The work itself on flushing the fuel system is inexpensive, only 1,980 rubles. The amount of costs is “pull up” by the fuel filter - with this procedure it makes no sense to wash the fuel and not change the filter, but it’s worth it, it’s not a wasteful expense.

If you receive a lot of questions about this process, in the next newsletter I can clearly tell and show you everything, with an arrangement and photo illustrations. I can add on my own behalf – flushing the fuel system is wow! I had no idea that my car was so agile and powerful, yo-ho-ho!!

I wrote the main and most probable reasons for a possible decrease in engine power - you need to remember that there are a great many such reasons, from engine malfunction to a sintered catalyst, from a faulty fuel pump to a dirty throttle valve. If you were unable to install them yourself, then you definitely need to go to us and entrust this task to professionals.

Power system pressure

The fuel pump is located in the gas tank on the injection engine. On carburetor engines, the pump will be found under the hood, on the engine. For most cars, power loss can be attributed specifically to the fuel pump.

Many modern cars have special connectors on the fuel line for connecting a pressure gauge. This way you can check the pressure. If the connector is missing, you will have to work a little to connect.

Pressure values can be found in the engine instructions. There is a special regulator in the line, with which you can relieve excess pressure directly into the tank. This regulator may be incorrectly configured, or it may leak. To check it you will need an ordinary air pump. Using it, you need to smoothly raise the pressure level to the one indicated in the passport for the motor. If you did not have time to increase the pressure, and the regulator dumped fuel into the tank, then it must be replaced.

How to understand why failure occurs when you press the accelerator

Often, the source of the problem is indicated by additional signs of a malfunction - for example, a “reluctant” engine start “on cold”, a general decrease in power (even before failures appear), increased fuel consumption. A very important criterion is when the problem manifests itself. If you notice that the engine spins up nonlinearly, as if there is a counterforce preventing it from gaining speed, most likely the reason is a clogged fuel or air filter. If the car “jerks” during acceleration with a smooth opening of the throttle, and, when pressed more intensely, it suddenly “shoots” - the jerks are associated with a lack of fuel. Dips during over-throttle and prolonged pressing and holding of the gas pedal, multiplied by difficult starting of a cold engine, indicate a malfunction of one or more spark plugs (and their coils).

Flooded or faulty spark plugs can also cause the gas pedal to fail.

The spark plugs that come with the car from the factory are more durable than most commercially available consumables, so the second and subsequent replacements are recommended to be done at shorter intervals.

Sometimes the problems of loss of throttle response, jerking, stepwise acceleration during acceleration are not at all related to the operation of the engine. On cars with automatic transmission, this is how severe wear appears. You will notice it when switching during acceleration - first a second delay without reaction to the gas pedal, then a push and acceleration. In cars with gas equipment, such a reaction to gas begins to occur when the gas reducer or its sensor breaks down. At the same time, the car begins to consume two to three times more gas. In diesel engines, an adequate response to vigorous pressing of the gas pedal is greatly impaired by refueling with low-quality fuel with a high sulfur content, or with a type of diesel fuel that does not correspond to the season.

Reason 7. Automatic transmission with surprise

If the car does not pick up speed, and you press hard on the gas, the reason may be in the automatic transmission. At the same time, you can hear that the engine is roaring like a wounded bison, but the power does not reach the wheels. To check if the problem is really in the automatic transmission, do the following:

Drive onto a flat road without turns. Set the handle to Drive.
Drive a couple of kilometers, observing the behavior of the car. If when you press the gas, the speed decreases, the problem is in the braking system. If the car does not pull and you hear a loud sound from the engine, then you need to check the automatic transmission.

It will not be possible to close the list with 7 reasons, however, the remaining breakdowns can only be calculated by a master diagnostician. We wish your horse not to break!

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.

Fuel system problems

There are many problems that cause the car to jerk when you press the gas. It is recommended to start checking with the sensors. DFID and TPS were discussed above. The malfunction may be caused by the crankshaft position sensor (CPS).

An electromagnetic device is necessary to synchronize the injectors and ignition in the system. The functionality can only be checked using an oscilloscope. If there are no pulses or are lubricated, the mechanism is faulty.

The problem is in the float chamber. The car will jerk sharply when you press the gas. There is not enough fuel in the chamber, the engine burns fuel faster.

The effect occurs due to problems in the fuel pump. You need to remove the cover and visually check the integrity and the sealing ring. Parts should be replaced if they become unusable. We need to get rid of the depressurization of the camera.

The fuel pump on the VAZ-2114 and other models with an injection engine is located under the rear seat. To access the device you need:

Remove the seat.
Open the cover fastenings.

It is not recommended to disassemble the fuel pump without experience; important elements can be damaged. On classic VAZ models, the mechanism is located under the hood.

The car may jerk due to a clogged filter in the pump. The part needs to be changed periodically; if it is completely clogged, fuel will not flow. The fuel system has two filters - fine and coarse.

Jerks when moving

The moment the car starts moving, most often there is a failure. Unpleasant sensations are associated with a delay in the engine's response to pressing the accelerator pedal. In some cases, the engine stalls. A jerk occurs when the throttle valve opens, when, based on a signal from its position sensor, the ECU determines the moment of transition from cold mode to load mode. This is aimed at increasing the amount of fuel supplied through the injectors. Due to insufficient pressure in the fuel line, there is not enough fuel to move the Lada Priora smoothly.

For this reason, the car stalls when accelerating. In this case, the electronic control unit of the engine, having received a message from the throttle position sensor about the intensive opening of the damper at a large angle, strives to increase the fuel supply as much as possible. This is impossible to do due to low fuel pressure.

During steady motion, jerking is caused by a malfunction of the ignition system. In this situation, the vehicle will need to be diagnosed and repaired. If this problem occurs on the road, then auto mechanics advise Lada Priora owners to follow these steps:

Maximum acceleration of Lada

inspect the space under the hood - turn off the ignition, and then check that the wiring harness blocks are securely attached to the ignition coils. You need to start the engine, listening to its operation: the crackling sound during a high voltage breakdown is weak, but clear. In complete darkness, a spark should be visible upon breakdown; replace the spark plugs, regardless of mileage and condition

You need to pay attention to the condition of the spark plugs: if it is abnormal, then you will need to repair the engine or its elements. Causes jerking during steady movement of Ladas with an injector; a possibly faulty throttle position sensor

Additional reasons confirming the malfunction of this unit are: uneven operation of the engine at idle, reduction in maximum engine power.

Ignition system

When you give gas, there is poor power, the engine does not pick up speed well, the reason may be hidden in the ignition system. This is true for any car with an internal combustion engine. It is necessary to make sure that the pads are fastened tightly, that there are no chips or cracks on the body, and that the armored wires are not damaged. Visually everything is intact. It is necessary to change the ignition coil or wires that have breakdowns with high voltage.

Attention! It is not recommended to change high-voltage wires in the absence of operating experience; the sequence must be observed. You should trust the professionals in the car service.

If all elements are intact, you need to check the spark plugs. A sign of a malfunction is that when going downhill, the vehicle begins to jerk, sometimes even on a flat road. This effect is explained by a weak spark or complete absence.

On cars with a carburetor engine, the ignition timing is set independently, a problem may arise. Early ignition is checked on the go - the speed is 50 km/h, 4th gear is engaged. You need to roll, then sharply press the gas. If everything is normal, there will be detonation for 1-2 seconds, in other cases it is necessary to set the ignition. This effect is also observed when the elements are in good condition.

If the high-voltage wires, coil and spark plugs are damaged, the problem lies in the control unit, which is important for carburetor engines with EFI (foreign cars). The car jerks after long trips. Diagnostics will help verify the breakdown; without equipment it is impossible to carry out such actions.

Classic ignition system

Reason 1. The food was so-so

The author of the article had a breathtakingly funny story. True, not with him personally, but with a friend. He once filled up with fuel at a well-known gas station. I filled it up and went on a date with the girl. And it’s frosty, winter outside. While we sat in the cafe and cooed at the cinema, it’s time to go home. But there’s no way to get home – the car doesn’t move. Well, no way at all: we haven’t tried everything, we haven’t read what forums. And so, on the advice of an experienced person, my friend decided to stick a branch into the gas tank and check the gasoline. And what do you think? Gasoline is frozen! That is, in general! Apparently the brave mixers overdid it with water in the fuel. Of course, they drove the car away, warmed it up and drained the gasoline, but a residue remained.

The quality of the fuel directly affects the behavior of the car. You can press the pedal to the floor as long and sharply as you like, but you will not achieve any effect. The car will sneeze, slow down and suffer along with you. The simplest thing is to drain the gasoline and pour 5 - 10 liters from another gas station. If this was the case, the symptoms will immediately disappear. And if it’s not in it, then pour the old one back in - don’t let the goodness go to waste. We wrote about the consequences of pouring low-quality fuel here.

Possible reasons for such a rare phenomenon

As mentioned above, a problematic phenomenon in modern engines, if it happens, is quite rare. However, this possibility should not be completely ruled out. But what is the reason for the failures? It is worth noting that even qualified workers are sometimes at a loss - everything can be so uncertain. However, if a car enthusiast has some skills in car repair, then you can try to do it yourself.

If we talk about engines with a carburetor, then this unit is most often the culprit. In this case, you need to configure it. As for modern units, it makes sense to conduct computer diagnostics of the car. There is a possibility of malfunctions in the electronic control unit (ECU).

The phenomenon itself occurs while the vehicle is moving, in particular when it picks up speed. Or the car just stands still with the engine running (idling). Let's look at some situations in more detail.

During acceleration

Sometimes the failure of the gas pedal appears only when the vehicle picks up speed. If you have certain skills, the owner of his iron horse is able to independently determine the cause. To do this, you should adhere to a suitable algorithm:

First of all, the inspection should start with the spark plugs. You also need to inspect the high-voltage wires for integrity.
If inspection of the spark plugs and wires did not reveal anything, then now it’s worth moving on to checking the throttle. When it is heavily polluted, the engine begins to respond with a noticeable delay in response to driver actions.
You also need to open the hood and inspect the air filter. It should be changed every 10,000-15,000 km.
Check and clean the injectors if necessary.
The fuel filter also needs inspection.

What question do you have? I will answer it and include it in the collection on the site.

In general, I expect questions from you, any questions, and about flushing the fuel system in particular.

Thanks to everyone who wrote to me last time that today is not Friday)))))). Eh, if it weren’t for you, I wouldn’t have gone to work, my child wouldn’t have gone to school, it wouldn’t have happened without trouble.

I wish you a good mood, total happiness and smooth roads! And clean fuel filters.

PS I'm waiting for your questions.

PPS If your question is of a technical nature, then I will ask a specialist about it myself, and I will tell you everything in a letter or by phone.

PPPS You can also come and chat with us and drink coffee. Just warn us that you will visit us so that you have coffee, time, and me.

Tatyana, Director of Automotive Development, was with you.

Sooner or later, every car enthusiast has to face the following problems:

The appearance of malfunctions in the operation of valves;
Sharp jerking of the car (there is a feeling that it is twitching on its own);
Lack of immediate response from 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.