Cause rich mixture on injector. Lean fuel-air mixture: injector, carburetor, HBO Rich mixture on a Nissan, what could be

Error P0172 is due to the fact that too rich a mixture is supplied to the cylinders. This is accompanied by the following symptoms:

• The engine seems to choke. When you press the gas pedal, the engine picks up speed with a delay, vibration is felt in the cabin.
• Black deposits form on the spark plugs.
• Fuel consumption increases, because. part of the fuel does not detonate and goes into the exhaust pipe.
• The dynamics of the car decreases, this is especially felt when overtaking and starting off.
• Float idle

To solve the problem, you need to check:

DMRV

It is highly likely that the sensor is transmitting incorrect data, due to which a rich mixture is supplied to the cylinders. It is especially important to pay attention to the sensor if there is also an error P0102.

MAP pressure sensor

The MAP sensor can also be the cause of code P0172. Check sensor:

• Check the connection of the contacts to the sensor.
• Check ground contact.
• The ideal option is to temporarily put a working MAP sensor from another car.

Air leak

Check for air leaks after the MAF sensor. Often, suctions are due to not fully twisted corrugations, the receiver. It is recommended to spray with a soap solution on those parts where air passes. Places where air passes will become noticeable. If the air leak is eliminated, reset the errors. P0172 should no longer appear.

fuel injectors

The next thing to check is the fuel injectors. First check if voltage is applied to each of them. There are special stands for checking injectors, but as a rule, they can not be found in every city.

Air filter

Check and, if necessary, replace the air filter.

throttle valve

Check the throttle sensor. For this

If the resistance is different, it is necessary to replace the TPS.

Absorber valve

The canister valve is controlled by the ECU. the valve could open and hang in such a position that it creates an extra air leak, which leads to P0172.

The error "The fuel supply system is too rich" most often appears in VAZ cars, in particular Kalina, Priora. And also in a number of others: Ford, Opel, Mercedes

Perhaps the most important feature of electronic fuel injection systems is the presence of feedback on the composition of the air-fuel mixture. Using a lambda probe, the engine control unit will determine at any time whether the mixture is rich or lean (if a narrow-band oxygen sensor is used). Or even accurately know the composition of the mixture (when installing a broadband sensor).

Rich-lean mixture

Next, the closed loop algorithm comes into play (in English terminology - closed loop). By constantly analyzing the signal from the oxygen sensor, the controller changes the composition of the fuel mixture each time the sensor voltage passes the threshold corresponding to the stoichiometric mixture (ideal fuel/oxygen ratio). Therefore, when the engine is running, the output voltage of the lambda probe has a form close to a sinusoid.

As soon as the voltage rises (the mixture turns from lean to rich), the controller, after waiting for a while, begins to gradually reduce the injection time, leaning the mixture. This continues until the voltage at the oxygen sensor drops, indicating a lean mixture. Further, the injection time increases again - that is why the algorithm is called the "closed loop".

Since, as the vehicle is used, the actual operating parameters can seriously deviate from the ideal ones set by the firmware, the parameter of long-term correction of the mixture composition is applied. It is set by a self-learning algorithm, and its work can be explained as follows: if for a long time the short-term correction (set by the lambda probe) deviates significantly from zero, then the average deviation value is taken into account when calculating the opening time of the injectors even before the short-term correction is applied.

For example, we have a faulty fuel pressure regulator that overestimates the amount of fuel actually entering the cylinders at the estimated injector opening time. Accordingly, the moment of transition from a lean to a rich mixture along the lambda probe will take place at a negative value of the short-term correction: the mixture will have to be depleted constantly. The self-learning algorithm will remember this negative correction.

Thus, even with serious deviations in the data from the sensors and the actual state of the engine, the injection system maintains the specified composition of the mixture. However, any correction has its limits, and when the correction parameters go beyond the limit values, the Check Engine indicator will light up.

Causes and symptoms of error P0172

As soon as the correction parameters (usually displayed as a percentage in diagnostic programs) fall below a predetermined threshold (for example, -70%), an error with the OBD-II code P0172 is automatically fixed. To understand the causes of such an error, you need to know that the composition of the ECU mixture itself is unknown, it is repelled solely from the voltage at the output of the lambda probe.

Dirty lambda probe

Therefore, the first reason that can cause the occurrence of error P0172 is the banal contamination of the measuring element of the lambda probe with soot. In this case, even with a very lean mixture, oxygen from the exhaust gases does not penetrate through the soot to the lambda probe, and the output will always be a signal corresponding to a rich mixture. Accordingly, the injection ECU will reduce the fuel trim parameter until it begins to go off scale. For the algorithm, this will cause the P0172 error to be indicated.

Without diagnosis, the symptoms are obvious. A cold engine starts normally or is slightly difficult (because the “closed loop” algorithm is turned off in the starting mode and when warming up), then the stability of the motor worsens, the car stalls under load. Candles are covered with white soot or even have traces of overheating (the combustion temperature of lean mixtures is higher). When diagnosing, there is no “sinusoid” at the output of the lambda probe, the voltage does not change even in forced idle modes, when the fuel supply is turned off, and a working oxygen sensor would definitely show a lean mixture.

However, the mixture can actually be rich. On vehicles equipped with a mass air flow sensor, one of the most likely causes is precisely a malfunction of the MAF. Over time, these sensors begin to overestimate the readings. If for VAZ engines the normal idle air consumption is 9-10 kg / h, then if the sensor malfunctions, it can be 15 or more. The author has seen a Gazelle, which literally flooded the engine with gasoline, because at idle its air consumption was allegedly 90 kg / h. Moreover, the primitive algorithm of the old "Mikas" did not even consider this a malfunction.

Based on the incorrect readings of the MAF, the injection ECU re-enriches the mixture when calculating the amount of fuel, and the “closed loop” algorithm takes the correction to a minus. This is diagnosed "on the knee" by excessive fuel consumption, black candles, and when the DMRV is turned off, the engine performance becomes better.

The sensors of the injection system may be serviceable, but the fuel is still consumed due to mechanical reasons:

• malfunction of the fuel pressure regulator, which does not dump excess into the return line (modern regulators are built into the fuel pump module and there is no physical return - “excess” fuel goes directly to the gas tank);

That is, the ECU calculates the injection time correctly, but in reality more fuel is supplied to the cylinders than the calculated one, and the “closed loop” again takes the corrections into a serious minus. It is also possible that the return hose itself is pinched on old cars with a drain ramp: the regulator would be happy to dump excess fuel into the tank, but it doesn’t work.

Immediately, all nozzles begin to “pouring” rarely, so this problem can be distinguished immediately: in one or two cylinders, the candles are blacker than in the others. If the overflow occurs due to a malfunction of the pressure regulator, then all the candles will be black. And connecting a pressure gauge to the rail will immediately give out a faulty fuel pressure regulator.

“Excess” fuel also appears due to a malfunction of the fuel vapor recovery system (in other words, an adsorber). This is easy to check by pinching the hose coming from the adsorber to the inlet.

And finally, excess fuel enters the cylinders and through the crankcase ventilation if gasoline gets into the oil. It is easy to “catch” this by increasing the level, a noticeable “dilution” of the oil, and a characteristic smell.

How to resolve the error

Regardless of the cause of error P0172, it is not worth delaying the repair, a rich mixture reduces the life of the catalyst. The most likely sources of problems are checked and eliminated first:

1. Examine the candles. Check for black deposits that the mixture is too rich.
2. On cars with a return line, remove the pipe from the regulator and try to blow it out to prevent it from being pinched anywhere along the way to the gas tank.
3. Find out the correct fuel pressure for your car. For a VAZ with a drain ramp, this is 3 bar, with a drainless one - 4. Please note that the pressure on the drain ramp is measured with the vacuum pipe removed from the regulator, otherwise the idle readings will be lower by 0.6-0.5 bar! The manometer itself for measurement can be inexpensively bought or borrowed.
4. Connect the tester to the signal wire of the lambda probe in voltage measurement mode. It is more convenient to use pointer devices - they do not have such inertia as digital ones, on a working lambda probe you can see the fluctuations of the arrow from 0.25 to 0.75 V.
5. Measure the voltage at the DMRV output with the engine turned off, comparing it with the reference one, if possible. For example, for VAZ sensors, it should not be higher than 1.03 V (Bosch) and 0.04 V (Siemens).
6. Check the level and condition of the engine oil.
7. Without “catching” the source of problems, contact the service - for a qualified diagnostician there will be no problems here.

Video: P0172 rich mixture

Seal

Most of the most modern cars still run on internal combustion engines - that is, principles more than 150 years old. Despite all the electronic, intelligent stuffing, engines of all manufacturers are still subject to typical diseases and internal combustion engine problems. One of these problems is a rich fuel mixture, which can make even a modern car with an injection engine look like a self-propelled carriage of the second half of the 19th century.

The symptoms of this problem are difficult to ignore and impossible to miss, regardless of driving experience. If your car's engine is running on a rich fuel mixture, you'll notice a number of warning signs:

• pops and shots coming from the silencer;
• black or gray smoke coming out of the exhaust pipe;
• the "Check engine" icon is lit on the dashboard;
• when reading, error P0172 is detected;
• dips in dynamics - the car seems to stumble;
• fuel consumption increases significantly;
• In advanced cases, the car may not start at all.

Of course, with such problems, the car is almost impossible to operate. Many car owners, especially inexperienced ones, are very frightened of such symptoms and consider this a serious breakdown, the correction of which will be expensive. In fact, everything is much simpler and more prosaic, and it can be expensive just to ignore the problem of a rich mixture for a long time.

What is a rich mixture

The name ICE itself suggests that fuel is burned inside the engine, in its cylinders. The process of burning something, as we know from the school curriculum, is the combination of molecules of something with oxygen molecules. Therefore, the engine needs a constant supply of air to run. The problem is that there is only 20% oxygen in the air, and the oxygen molecules themselves are much smaller than gasoline molecules, so for proper combustion, almost 15 times more air is needed than the fuel itself.

A rich fuel mixture is formed when this ratio is violated for some reason - more gasoline is supplied than necessary. This is not good, because gasoline no longer burns completely - it simply does not have enough oxygen for this. Excess fuel is ejected from the cylinder along with the exhaust gases into the exhaust system. Because of this, the engine does not receive some part of the power on each cycle, it literally starts to choke. In some cases, gasoline can simply fill the cylinders, and then it will not be able to burn at all.

Reasons for the formation of a rich mixture

Most often, a rich mixture is formed not due to the fact that more fuel is supplied than necessary, but due to the fact that less air is supplied than necessary. The most common and common cause is a clogged air filter. Alas, many motorists forget that some components need to be changed regularly, even if they look like new. The air filter is one of these units, it needs to be changed at least every 30 thousand kilometers, and on powerful cars even more often.

Also, the air supply can be “cut off” by an incorrectly working air pressure sensor. Paired with it is a fuel pressure sensor, which can also supply underestimated data to the electronic engine control unit. Based on them, the block begins to pump more fuel into the cylinders, enriching the mixture. It, as we learned above, worsens power and dynamics, the control unit does not like it, and it supplies even more gasoline. Hence - a strongly growing fuel consumption.

The reason for a rich fuel mixture may also be hidden in the electronic engine control unit itself. These may be errors in his program, but also incorrectly made changes to it. Self-taught craftsmen and simply unskilled craftsmen "tune" the control unit, deliberately increasing the proportion of fuel in the mixture. So you can achieve a small increase in power, but it is much easier to upset the balance and achieve the opposite result.

The fuel pump can also disrupt the proportions of gasoline and air, pumping much more fuel into the system than necessary. And the most difficult reason to determine is the malfunction of the injectors in the cylinders. They can become clogged or deformed, and then the balance of the fuel-air mixture can fluctuate in any direction.

Consequences of driving on a rich mixture

Riding on a rich mixture will not bring anything good. If the problem is not solved in time, it can lead to the following consequences:

• burnout and other breakdowns of the muffler and catalyst, tk. the thrown fuel begins to burn out in the exhaust system - hence the black smoke, pops and shots;
• an oily residue forms on the walls of the engine exhaust system, which clogs it, and after a long time it may be necessary to completely clean the system;
• the percentage of harmful impurities in the exhaust gases increases sharply, which harms the environment and reduces the life of the catalyst;
• unexpected dips in dynamics can be very dangerous for you and other road users.

So at the first sign of enrichment of the fuel mixture, it is better to immediately visit a car service. Moreover, the problem is very quickly and easily determined by the on-board computer memory scanner - it displays error P0172. Also, in many cases, repairs are inexpensive and fairly quick.

In modern cars, and the VAZ-2114 can be called relatively modern for another two or three years, engines with an injection power system are installed. A fairly simple injection scheme is also implemented on the VAZ-2114. However, it can also confuse the owner. The injection power system practically does not require adjustment, it can relax in terms of maintenance and operation, but for the time being, on the display P0172.

What is a rich mixture and error P0172

Too rich a mixture on the VAZ-2114 can happen for several reasons, but the main, most characteristic sign of such a failure will be the error message P0172. Of course, the error can be ignored and reset. However, it is more difficult to discount a whole bunch of symptoms of unstable and incorrect engine operation.

Error P0172 on the on-board computer screen

To begin with, it is worth knowing that a re-enriched mixture is a state of the fuel-air mixture, when the amount of fuel significantly exceeds the allowable rate and prevails proportionally over the amount of air.

Error P0172, what to do?

Consider if software settings have been changed. It is quite possible that after "light chip tuning" by a fuel systems engineer known to the whole cooperative, flashing the controller, the engine can work correctly for some time. However, there is a good chance that the operating ratings of the sensors are incompatible with the new settings. Therefore, the fuel supply will be carried out incorrectly.

It is also possible that the injection system may malfunction after replacing the oxygen sensor, or any of the sensors that are related to the engine power system.

If the malfunction arose “by itself”, and all the problems listed above do not concern this motor, it is necessary to carry out high-quality computer diagnostics of the engine.

Norms of air in the fuel mixture

Fuel mixture diagram

An average engine needs approximately 15 kg of air and one kg of gasoline to operate normally. If this proportion is shifted towards the air, then, if vice versa - rich.

Of course, in different operating modes, the proportions of air and fuel can be different and they must be fully controlled by electronics using several sensors. Thus, with a lean mixture, the fuel consumption will be slightly lower than the passport one, but the engine characteristics will not correspond to the nominal ones.

The appearance of the spark plug with a re-enriched mixture

In addition, there are a number of other symptoms that are immediately noticeable:

1. Strong pops in the muffler , regardless of the speed, more often at high. This is because unburned fuel in the combustion chamber invariably ends up in the exhaust system along with the exhaust gases. It cannot leave the silencer as easily as gases do, so it accumulates in the labyrinths of the silencer and ignites or explodes when a certain temperature is reached. This is fraught not only with special sound effects, but also with torn or torn off resonators and silencers.
2. Exhaust smoke becomes dark or black . This happens for the reason that the fuel burning in the exhaust system is not filtered by anything, more precisely, the gas from the combustion of gasoline in the muffler is not filtered.
3. Engine noticeably loses power . The over-enriched air-fuel mixture burns slowly and incompletely, gasoline residues splatter the candles, significantly worsening the sparking process. Consequently, the mixture does not burn out completely, the piston does not receive the optimal force,. At times, especially after driving at high speed, again, but not for long. Until the rich mixture fills the candles again.

   Visual inspection of spark plugs

4. Naturally, this may mean huge fuel consumption - despite a failure in the control system, the fuel still continues to be supplied to the combustion chamber, where it is used extremely inefficiently and most of it literally flies into the pipe.

When and how does the mixture get too rich?

Despite the fact that we now blame gasoline for having too much of it, in fact, most often it turns out that the proportion of the mixture is knocked down precisely because of less air.

The first thing to do, and this is the easiest,. It can be tritely clogged, so the right amount of air has ceased to enter the combustion chamber.

If the filter is obviously clean, then there may be several reasons:

1. Incorrectly adjusted nozzles . They may open and close on time, but the amount of injected fuel may be too large. As a rule, it can only be carried out on a special stand, as well as their cleaning and adjustment. But more often than not,

   New mass air flow sensor

2. Too high fuel pressure in the rail . The pressure in the fuel rail is easy to check, and this may be due to the fact that the return hose is simply pinched. It could also be a faulty pressure regulator.
3. A crash can cause a hit a large amount of gasoline in the lubrication system , especially often this occurs in the cold season, when it is difficult to start the engine.
4. If the malfunction is of a floating nature, it is quite possible that there is no or intermittent contact on one of the terminal blocks . Each of them will have to be checked separately.