"Poor mixture" - what is it? Causes of education, consequences

In order for the car to work well, the engine needs high-quality food. In order to produce an explosion in the combustion chambers of the required power, the mixture of fuel and air must have been of high quality. Sometimes it is prepared with deviations in one or the other direction. This is a poor mixture, or vice versa - rich. What is it, what causes the poor fuel mixture, the symptoms and how the engine works? Let's try to answer these questions.

The process of mixture formation in car engines

In the ICE, a combustible mixture of the required composition is prepared in carburettors or in the case of an injector power system - calculated by electronics. A mixture where 15 kg of air is used per kg of gasoline or other fuel is considered normal. In this mode, the engine runs quite economically, while its power is at a high level. To save, the amount of air in the mixture is increased. Thus, a lean mixture is when 15 liters of air are used per liter of gasoline. Fuel consumption becomes minimal, and power losses are only 8-10%. Poor mixture is when more than 17 kg of air per 1 liter of gasoline. On this composition, the motor is unstable, a large amount of fuel is consumed, and power is reduced. This is harmful to the power unit. In addition, this phenomenon often leads to a gap in the ignition system, delays when pressing the accelerator pedal.

Also, the motor can change the sound of the operation and will be unstable. In the injector units, which correspond to Euro 2, a lambda probe is installed. It controls the quality of the fuel mixture supplied to the combustion chambers.

Why the mixture becomes poor

Owners of injection vehicles know that with the help of the computer and the appropriate settings in the firmware the power unit can independently change the ratio of air and gasoline vapors, that is, change the fuel mixture. Many people think that the motor works automatically, and that's good. However, most owners of injection cars forget about balance. Sometimes a poor mixture is prepared. Why does this happen? There are various reasons for this.

The main signs of depletion of the composition of the fuel mixture

The main symptom by which it is determined that the car is working on the wrong composition is the engine, which is constantly deaf. With a very small amount of gasoline vapor in the mixture, the spark generated by the candle simply can not ignite such fuel. Another sign - the machine is twitching in the process of motion, or even moves at all jerks. Sometimes these symptoms can also speak of other malfunctions. Therefore, it is worth checking out other systems. On whether a poor fuel-air mixture is being prepared, one can understand by candlelight. But this is relevant only for the injector units. If they are brown - the engine is in perfect order. If the candles are white or light - then there is a lot of air in the fuel composition. If the element showed a dark build-up, this indicates a lack of air. However, carbon deposits are not always the right indicator of the wrong mix. In the case of an incorrect timing of ignition, the color of the candle does not match the normal. If a depleted mixture is supplied to the engine, the owner of the car will hear characteristic claps in the muffler. When just a poor mixture, it will shoot like an automaton. If on the contrary, the fuel composition is too rich, then the explosions will be single and short. And finally, the most accurate indication and method of diagnosis is the exhaust gas check with a gas analyzer. If the engine is operating in the wrong mode, the on-board computer or diagnostic system will also report this. In the list of errors of modern ECU there is a mistake - a poor mixture. It is designated P0171.

The consequences of running the engine on a lean mixture

In general, the consequences are not so much. The engine will suffocate when idling. There is also a serious risk of overheating - the fuel mixture burns much more slowly than necessary. The engine will be difficult to gain momentum under load. In the most serious situations, when a poor mixture is fed for a long time, the engine overheats, which in most cases leads to a burnout of the valves. And this is a serious cost of repairs. Also among the consequences can be allocated a huge fuel consumption. It increases due to difficulties in the process of recruiting. Therefore, car owners with such problems are recommended to ride at low gears.

The reasons for preparing a lean mixture

There are several typical reasons why a fuel mixture is not cooked properly. All these reasons can be divided into a large volume of air and a small amount of fuel. Errors associated with a poor mixture can often occur in the case of a large air supply. In this case, it is recommended to check the fuel consumption sensor - very often the sensor channels become dirty. The second reason is vacuum leakage. The third is the EGR valve, which draws in additional air. The valve may be broken or not closed securely. If the poor mixture enters the cylinders, the reasons are injector, ignition, fuel system, a violation in the work of the gas distribution system.

How to check the EGR valve

To test the operation of this valve, it is first dismantled and then checked. The test can be carried out using a jet of compressed air. Air is fed into one of the holes - the valve should work. You can see this at the top through the hole. The valve clogs due to the presence of dirty air in it. Carbon deposits form on the nest or plate of the element. The valve jams, and as a result, the wrong mixture is prepared, and often too poor.

DFM sensor

Sometimes you need to check everything you can. It is worth starting with the diagnostics of sensors. As you know, one of the most popular problems is a clogged or clogged air flow sensor. If a lot of dirt accumulates on it, it often leads to a slow response of the computer to the air flow and its shift. Additionally, the sensor can be contaminated by fumes of fuel that pass through the intake manifold. In addition, the plaque can accumulate through the throttle body when the motor does not work. A layer of paraffin is deposited on the sensor, which causes incorrect data on the proportions of the fuel mixture in the ECU. Then comes the situation when the engine control unit can not add the right amount of fuel to the mixture (the amount of air is already large enough). And then an error appears on the sensor display - a poor fuel mixture.

Faults in the intake system

To eliminate the lean mixture problem, it is also recommended to perform a throttle valve diagnosis. The position of the damper must clearly correspond to the position of the accelerator pedal. If the throttle valve is automatic, it is important to pay attention to ensure that its position corresponds to the temperature of the power unit. On a hot engine, it must be fully open, on a cold engine - it is turned to a certain angle. If the damper is open, then the air damper control system is faulty. What else do they sin in the event that a poor mixture forms in the motor? The reasons are the injector and the damaged gaskets of the intake manifold. To eliminate this fault, it is recommended to tighten the manifold and, if necessary, replace the gaskets.

Problems with timing

In order for the gas distribution mechanism to have no effect on the depletion of the fuel mixture, it must be checked. And, if necessary, adjust. When examining the gas distribution mechanism, special attention is paid to the tension roller and to the belt (its condition and marks). If the drive is chain, then check the chain together with the tensioner system.

Fuel system

Checking the fuel system will not be superfluous. It is important to check the performance of the injectors, but this can only be done with special equipment. Often, most of the problems of injectors are associated with low-quality gasoline - then you can get rid of a simple flushing of these parts. Then check the fuel pressure level and the performance of the gasoline pump, if there is one in the system. The pump is checked for voltage. Among other things, check the fuel pressure regulator and the fuel filter.

False Errors

It happens that the system, along with the errors of the poor mixture, produces other codes. For example, p0100 or p0102. It immediately shows that the reason for the sensor. To solve the problem, the sensor must be cleaned. For these purposes it is recommended to use special means for cleaning electrical appliances. But it's better to replace.

Lean mixture codes

Do not think that if there is a "poor mix" error, only one code reports this. For example, P0171 is standard, but for Ford cars this code reports problems in the first cylinder. In some models from Honda, there may be an error P0172, which reports a poor mixture. On the popular Chevrolet Captiva, the problem with the mixture is indicated differently - P2177. But for elimination it is necessary to use universal methods. The Japanese car Mazda-6 appears code 2178, which also indicates a poor mixture. All this is determined by the method of computer diagnostics.

Repair as soon as possible

It should be remembered that if the engine has been exploited for a long time with such problems, it can significantly reduce its life. The lean mixture can cause premature failure of a huge number of different units and assemblies. In this case, the repair will be much more expensive than if the diagnostic is performed in time and the fault is rectified.