Who holds the car “by the tail” and what causes such an effect

Sometimes a car can suddenly lose traction. The driver presses the pedal, but the car does not move. Or rides, but very slowly, although the engine speed is close to maximum. Why does this happen, and what prevents the car from moving normally? Let's try to find out.

When does cravings disappear and why does it happen?

The car engine can stop working properly at any time. There are many reasons why engine power drops sharply. It is not possible to list them all within the framework of one small article, so let's focus on the most common ones:

• bad gasoline. If the car is “held by the tail”, then in about 60% of cases this is due to the low quality of the fuel. And the car owner can mistakenly pour the wrong gasoline into the car. For example, AI92 instead of AI95;
• problems in the ignition system. In particular, the ignition of the fuel mixture can occur too early, when the pistons in the engine have just begun to rise to the combustion chambers. If a spark occurs at this point, the pressure from the exploding fuel will prevent the piston from reaching top dead center. And with the correct operation of the ignition, the piston freely reaches the upper position, and only after that does a flash occur, throwing it down. An engine in which the ignition is advanced is, in principle, not capable of developing full power;
• fuel pump problems. This unit has filters that may become clogged, or the pump itself may not work properly. As a result, the power supply to the engine is disrupted and power failures will not take long;
  

  Often engine power drops due to a faulty fuel pump.
• fuel line problems. Over time, they can lose their tightness, either due to physical wear or mechanical damage. The result will be the same: air will begin to enter the fuel system, which should not be there. The composition of the fuel mixture will change, it will become lean, and the car will be “held by the tail”;
• injector failure. They may fail or become clogged. As a result, the mode of fuel injection into the combustion chambers is disrupted, and the engine loses power;
• failure of one or more sensors in the vehicle's electronic control unit. These devices are responsible for collecting data, based on which various modes of the engine and fuel system are turned on (or turned off). Faulty sensors transmit incorrect information to the electronic unit. As a result, the operation of the engine and fuel system is disrupted, which can lead to power failures;
• timing problems. The gas distribution mechanism settings can go wrong over time. This is usually due to the timing chain stretching and sagging slightly. As a result, gas distribution cycles are disrupted, and a layer of soot gradually appears in the combustion chambers, which does not allow the valves to close tightly. Gases from the combustion of the fuel mixture break out of the combustion chambers, overheating the engine. At the same time, its power decreases, which is especially noticeable when accelerating.
  

  The timing chain is very stretched and sagged, which led to a loss of engine power

On which cars and why does the problem occur

As mentioned above, the loss of power in 60% of cases is associated with bad gasoline. Therefore, first of all, the problem concerns cars that are demanding on fuel. These include:

• BMW, Mercedes and Volkswagen cars. All these machines require high quality gasoline. And there are often problems with it at domestic gas stations;
• Nissan and Mitsubishi cars. The weak point of many Japanese cars is fuel pumps and their filters, which owners often forget to check;
• classic VAZ models. Their fuel systems, as well as ignition systems, have never been stable. This is especially true of older carburetor models.

How to determine the cause of poor engine thrust

To find out why the motor does not pull, the driver has to act by elimination:

• first, the quality of gasoline is checked;
• then the ignition system;
• fuel system;
• timing system.

Consider the actions of the car owner, depending on the reasons due to which the engine power was lost.

Poor quality gasoline

The sequence of actions in this case may be as follows:

1. Half of the fuel is drained from the tank. In its place, new fuel is poured, purchased at another gas station. If the thrust returned, the problem was in gasoline, and other options can not be considered.
2. If the driver does not want to dilute gasoline, but is sure that the problem is in the fuel, you can simply inspect the spark plugs. For example, if gasoline contains a lot of metal impurities, then the skirt and spark plug electrode will be covered with a bright brown soot. If there is moisture in gasoline, the candles will become whitish. If these signs are found, the fuel should be drained, the fuel system flushed and the gas station changed.
   

   White coating on candles indicates poor quality gasoline

Lost ignition settings

Usually this phenomenon is accompanied by a constant knock of the pistons. This is a sign of engine knock. If the driver is experienced, he can independently adjust the ignition. Let's illustrate this with the example of VAZ 2105:

1. The spark plug is unscrewed from the first cylinder. The candle hole is closed with a plug, and the crankshaft is gently turned clockwise with a key until a full ignition stroke is found.
   

   The candle is unscrewed with a special candle wrench
2. There is a notch on the crankshaft pulley. It must be combined with the risk on the cylinder block cover.
   

   The marks on the cover and crankshaft must be aligned.
3. The distributor turns so that its slider is directed towards the high-voltage wire.
4. The candle is screwed to the wire, the crankshaft is turned again with a key. A spark between the contacts of the candle should occur strictly at the end of the compression stroke.
5. After that, the distributor is fixed with a 14 key, the candle is screwed into a regular place and connected to a high-voltage wire.

Video: installation of electronic ignition on the "classic"

How to install electronic ignition VAZ classic

But not on all cars, the process of adjusting the ignition is so simple. If the car owner does not have the proper experience, there is only one option: go to a car service.

Fuel system problems

With some problems in the fuel system, the driver may well figure it out on his own. For example, he can change a clogged filter in a gasoline pump or the pump itself with his own hands. In most cars, this device is located under the cabin floor, and to get to it, you just need to lift the mat and open a special hatch. Also, the pump can be located under the bottom of the machine. Here is an example of replacing a pump on a Mercedes-Benz E-class Estate:

1. The car is placed on a flyover or viewing hole.
2. The pump is located in front of the fuel tank. It is installed under a plastic casing, which is fastened with latches. The cover is removed manually.
   

   Plastic casing of the fuel pump, held on by latches
3. A small basin is installed on the floor to drain gasoline from the hoses.
4. On one side, the pump is attached to the fuel hose with a clamp. The bolt on the clamp is loosened with a Phillips screwdriver. On the opposite side, the device rests on two 13 bolts. They are unscrewed with an open-end wrench.
   

   The clamp on the pump hose is loosened with a screwdriver
5. The pump is removed and replaced with a new one. The protective cover is returned to its original place.
   

   The new pump is installed, it remains to return the protective cover to its place

Important point: all work is carried out in goggles and gloves. Fuel splashed into the eyes can cause blindness. The room in which the machine is parked must be well ventilated and there must be no sources of open fire nearby.

But the serviceability of the injectors is checked on a special stand, which is only in the service center. It also carries out diagnostics of fuel lines and checking their tightness. Even an experienced car owner cannot find and fix all these malfunctions on their own without special equipment.

Malfunctions in the ECU and timing

When solving these problems, too, one cannot do without diagnostic equipment and a qualified auto mechanic. An experienced driver will be able to independently change a sagging timing chain on a VAZ car. Doing the same on a foreign-made car will be much more difficult. The same is true for the control unit.

The engine control unit from a Mercedes car cannot be repaired in a garage

You can't test it without special equipment. So if the driver has consistently ruled out problems with fuel, ignition, fuel system and it remains only to check the ECU and timing, the car will have to be driven to a car service.

Estimated repair cost

The cost of diagnostics and repairs depends both on the brand of the car and on the prices at the service center. Therefore, the numbers can vary widely. In addition, maintenance of German cars usually costs much more than Japanese and Russian ones. With all these points taken into account, the prices look like this:

• checking the fuel system, replacing pumps and filters - from 4 to 8 thousand rubles;
• purge and replacement of nozzles - from 3 to 12 thousand rubles;
• checking and tuning the timing system - from 5 to 18 thousand rubles;
• computer diagnostics and replacement of sensors - from 2 to 8 thousand rubles.

preventive measures

Having restored the engine traction, the driver should take care that the problem does not arise in the future. Here are some preventive measures:

• fuel quality control. At least once a month, you need to inspect the spark plugs for brown soot and white deposits;
• timely maintenance. The frequency of this event depends on the car model. In some cases, drivers do not pass the next MOT, either due to lack of money, or because of banal laziness. But even if it seems to the car owner that everything is in order with the car, it is far from a fact that it is so. And you can find out only with the help of diagnostic equipment. So it is categorically not recommended to neglect technical inspection;
• checking timing chain tension. For such a test, no special skills are required. It is enough to unscrew the bolts on the timing block and pull the chain by hand. If it sags a lot, the car owner will immediately feel it;
• checking the filters on the fuel pump. Another measure that many drivers forget about. Once every three weeks, open the pump hatch and evaluate the condition of the filters. On German cars, they get dirty very quickly, taking into account the quality of domestic fuel. Dirty filters should be changed immediately.
  

  If the filters in the fuel pump are dirty, they should be changed immediately.

So, the loss of traction by a car is a multifactorial problem. To solve it, the driver has to go through all the possible options for a long time, acting by the method of elimination. Most often, the problem turns out to be low-quality fuel. But if not, then without a full-fledged computer diagnostics and the help of qualified mechanics, you won’t be able to figure it out.