Question from a reader.

« Hello Sergey and all readers of the siteauto-blogger.ru, just want to say thank you especially for your answers to readers. So I decided to ask you a question about my VAZ 2114. I have a LUX version with an on-board computer. Lately I've noticed that my fuel consumption has increased. If earlier, about six months ago, the consumption was 7.5 - 8 liters in the city, now, according to the bortovik, 9.5 - 10.5 liters, although I also drive along the same road to work, and it's not winter yet! How to explain such fuel consumption? I noticed that the consumption began to grow after a trip to the south, 1700 there and 1700 back, about 3500 kilometers, maybe the fuel is not of high quality, did something clog with me? In the morning I noticed that the engine detonates a little (troit), could the consumption be related to this? Help with advice Sergey, fuel consumption has just been scaring me lately! Waiting for an answer, Arthur"

I'll try to help Arthur. This consumption may depend on several reasons, some you can fix yourself, and some need to be fixed at the station. But everything is in order ...

Ignition system

The first reason is the ignition system. Weak points are candles, high-voltage wires and ignition coils.

If you have high mileage and have never changed, then they just need to be replaced. From our "high-quality" fuel, candles die quickly, on average, on one set, I advise you to drive 20 - 30,000 kilometers, if you have them, then the mileage increases slightly to 30 - 45,000 kilometers. It’s not worth saving on candles, you need to take proven brands, preferably in official stores or service stations, let them be a little more expensive, but they will work longer and better. Your morning knock may be due to faulty spark plugs, and fuel consumption may be due to them too.

These are the wires that go from the ignition coils to the spark plugs. They also often fail, under the influence of external factors, they can break through and the spark will “leave” - as auto electricians say. That is, the candle will not have enough voltage and will not be able to qualitatively ignite the fuel, this can also triple the engine and increase fuel consumption. It is quite easy to check broken wires, you need to open the hood at night, start the car and look at the wires, it is advisable to cover yourself with something else so that the light does not get into the engine compartment, if a spark runs through any wire, then this wire needs to be urgently replaced, it is advisable to change the entire group of wires. Soon I will write an article - how to check high-voltage wires.

As a rule, an injection car has two or four of them, each is responsible for its two to four cylinders. The coil can also fail, but it is already more difficult to determine its malfunction, for this you need to measure the voltage, you need to contact the service station. Due to the ignition coil, the engine will also triple and there will be increased fuel consumption.

Fuel supply system

The second reason for increased fuel consumption is the fuel supply system. It consists of a fuel pump, nozzles - filters and a fuel injection mechanism, usually a fuel rail with injectors.

It stands in the tank, is in the nutria of the fuel, from our gasoline, the mesh that filters out small and large debris can often become clogged. The gas pump will strain, and supply either a high pressure of fuel, or a low one, this may give the impression that the engine is troit, there will also be no traction, the car, as they say, will be “cotton”. Fuel consumption will also increase. You just need to pull the fuel pump and clean it. If the fuel pump breaks completely, then your car will simply stand up.

If it is more or less clear with the pipes, they are unlikely to become clogged, then here are the fuel filters, this is a direct reason for the increased fuel consumption. Over time, the fuel filter becomes clogged and needs to be changed. In our realities, replacing the fuel filter should take place every 10 - 20,000 kilometers. If the filter is clogged, then the engine also does not receive the fuel mixture, the car simply does not drive.

I once wrote that the fuel rail needs to be cleaned, and the more often the better. On my FORD FUSION, after a long run, fuel consumption also increased, by about 1 - 1.5 liters, and traction disappeared. After, the car became completely different, traction appeared and fuel consumption decreased. Therefore, it is necessary every 50 - 60,000 kilometers, and maybe even earlier, to clean the injector from any deposits. You are unlikely to do it yourself, you need to carry out work at the service station.

By filtration system, I mean an air filter that filters the air taken from the environment. It clogs from dust and dirt, the engine does not get enough air, the consumption increases. There were cases when only replacing the engine air filter gave fuel savings of 0.5 - 1 liter. It is not very difficult to replace yourself. It is advisable to change the engine air filter every time the engine oil is changed.

Banal reasons for fuel consumption

There was a case, one of my acquaintances also increased consumption on our VAZ, began to eat more by 1 - 1.5 liters. All climbed all right, and the ignition system, and fuel supply and air filtration. But here the car spends more and that's it. Everything turned out to be simple. The rear brake pads were recently changed on the car and the handbrake was pulled almost to the limit, so that with one click up, the car could not be moved. We went back to the service station, slightly loosened the handbrake, so that with 3 - 4 clicks the car was fixed.

High fuel consumption is usually attributed to malfunctions of the car's electronic systems, is this always the case? Now let's find out...

Let's start with the simplest. How do you measure fuel consumption on your car?? If the increased cost of gasoline, then it's stupid (no offense). It is also stupid to measure the consumption of gasoline in the direction of the arrow on the fuel gauge. First of all, you need to correctly measure the flow rate on your car. Of course, the data will still be approximate, but already more accurate than the definition of “by eye” and “by sensations”.

First you need to correctly measure the increased fuel consumption

Fill up a full tank of fuel. You may not be able to fill gasoline to the top of the neck, because many fuel tanks have a check valve, it does not let fuel out through the filler hole. But the tank needs to be filled as accurately as possible!

Now you need to reset the odometer to zero, and you can go. You need to drive along the highway at an average speed of 90 km / h, without sudden accelerations and braking. The more kilometers you drive, the more accurate the measurement will be.

The most effective fuel saver, according to our readers, is the High Performance Fuel Saver. The fuel passes through the magnetic field created by the FUELFREE fuel saver. The fuel molecules are evenly distributed, and its combustion in the engine becomes more efficient. Thereby gasoline consumption(or diesel, who drives what) reduced by 30-40%.

After the trip, top up the tank again to the full (preferably at the same gas station and from the same pistol, because they can snap off in different ways.) Topping up the tank to the full, you will find out how many liters you spent on the train, and look at the odometer mileage. Now there is all the data to find out the consumption.

Divide the number of liters used by the kilometers traveled and multiply all this by 100. You will get gasoline consumption per 100 kilometers.

Example: Let's say you drove 86 kilometers and spent 6 liters of gasoline on this trip. We divide 6 by 86, and multiply the resulting figure by 100. We get approximately 6.98 liters. That is, the consumption is about 7 liters per hundred.

Keep in mind when measuring:

• What you may miss at some gas stations
• The quality of the fuel greatly affects the distance traveled.
• Driving style largely determines the efficiency of the motor

Main reasons

In most cases, high fuel consumption is the cause of the malfunction. We will now talk about these malfunctions and consider the causes of increased fuel consumption.

Fuel rail pressure. Low or high pressure causes high fuel consumption. Check the pressure with a special fuel gauge. The pressure may drop due to a clogged mesh filter on the fuel pump, or due to the "fatigue" of the fuel pump itself.

When the pressure in the fuel rail drops below normal, the engine power decreases, which forces the driver to press the gas pedal harder, and this causes high fuel consumption. The pressure norm for all machines is different, but limits can be distinguished from 2.6 to 4 kPa. These are average pressures with the engine running.

Voltage in the car network. Unstable voltage directly affects the performance of injectors.

The control unit calculates the injection time, taking into account, among other things, the voltage of the vehicle's on-board network. Check the stability of the output voltage from the generator. You can do this with a multimeter with the engine running.

oxygen sensor. If it malfunctions or incorrect readings, the “check” may not light up, but the consumption will be increased. The fact is that the oxygenator is responsible for the optimal adjustment of the fuel supply, and if it is faulty, then the flow rate inevitably increases.

Well, if the mileage of your car is more than 100 thousand and the sensor has never changed, be sure that it shows incorrectly. Sensor resource approximately 80,000 kilometers

Coolant temperature sensor. If fuel consumption has increased, then DTOZH may be the cause. When the temperature sensor is false, the ECU may unreasonably increase fuel supply, mistakenly thinking that the engine is cold.

The fact is that for a cold engine, the mixture is made more enriched, that is, more gasoline is supplied than in a hot engine.

High RPM idling can also be the cause of high consumption. The revs themselves may increase due to the throttle position sensor.

Clogged fuel injectors. With a decrease in the quality of spray on clogged nozzles, fuel consumption increases significantly. At the same time, the acceleration dynamics may drop significantly. The car starts to "stupid", that is, it accelerates poorly. Sometimes misfires can occur, causing unburned fuel to burn out in the catalyst.

Air filter. A clogged air filter prevents sufficient air from entering the cylinders. Because the mixture becomes rich. The oxygen sensor, of course, regulates the composition of the mixture, but as a result, the engine power drops and the driver presses the pedal again, thinking about why the car has a high gas mileage.

With a heavily clogged air filter, engine speed may not rise to the possible limit.

Cold engine. If the engine is not warmed up to operating temperature (on Solano and Smiley 92 - 98 degrees, on Geely Emgrand and Lifan X60 - 95 degrees.) On a cold engine, the ECU prepares a re-enriched mixture for a successful start. But if the mixture is rich while driving, this will cause a strong overspending of gasoline. When the engine is overheated, a similar situation occurs.

Camshaft position sensor. In the systems of modern cars, multi-point injection is organized, which is provided by a camshaft sensor. When the sensor fails, the system switches to asynchronous injection, fuel is injected into all cylinders simultaneously, regardless of the phase of the pistons.

Multipoint or multiport fuel injection is a process in which gasoline is injected into each cylinder separately and only on the intake stroke. With asynchronous injection, fuel is injected into all cylinders at the same time, but in a smaller amount.

Use of leaded gasoline! At the beginning of the 20th century, Americans came up with a way to raise the octane number of gasoline. They just added tetraethyl lead to it. Such gasoline is called leaded. Tetraethyl lead additive is highly toxic. In addition, a lead film settles on the oxygen sensor and "poisons" it. The oxygen sensor starts to lie and fuel consumption is constantly increasing.

What does it mean? This means that when refueling with gasoline with a higher octane rating (95, 98), you run the risk of running into exactly the “planted” fuel. The higher the octane rating, the less knocking of the fuel (self-ignition during compression). But in this case, more is not always better. Although the 92nd is not immune to fraud, it still has more confidence.

Ignition system. Even if occasionally, the fuel consumption will be greater. Gasoline from a non-working cylinder is directly thrown into the pipe and, in addition, kills the catalyst. Check the ignition system, wires, modules and spark plugs for possible "breakdown".

Mass air flow sensor. Or in some cars intake manifold absolute pressure sensor. The readings of these sensors are used to adjust the injection time and the composition of the fuel-air mixture, therefore, if they do not work correctly, the consumption increases by leaps and bounds.

SORRY FOR OFF-TOP!
BUT ON THE IDEA_USEFUL.
THOSE. WHAT NOT EVERYTHING IS SO IN THE CAR IS DEFINITELY!
(authorship is not mine. This is copyright. Taken from other forums)

________________

A topic like "does not pick up speed when I press on the gas?!?!?"

Something must have broken.
Are you aware that you don't have a cable from the gas pedal to the throttle? That is, when you press the gas pedal, there is no mechanical opening of the throttle. Or the following might happen:
ECM (engine control unit) Guys! Received a digital signal from the throttle pedal that the car should go faster by 53%, report ready!
Front Lambda - tell the injectors not to pour gasoline drain, I say that DOFISH it!
Rear Lambda - Damn! Girlfriend! I have enough of it here, but how do you work there? And the poor catalytic converter has finally been rumbling with displeasure lately, although it used to squeak.
ECM - Yes! Harosh market! Moreover, you are not in business in this operation, because if you listen to you, then the car will never accelerate.
Nozzles - What are we? They opened us at a lope - we missed the runoff. The massmeter is probably lying, but they are slandering us.
Massmeter - Lana! I have been working here for 5 years and it’s not easy to slander me, it’s better to ask with candles, they have been sentenced more than once in my lifetime.
Candles - Kaneshna! Some counted, others missed it, but then we have to burn all this muck! So not only is the gasoline *****, but also the compression is awful.
Piston rings - What can we do? If only they poured human oil and changed it regularly, and then it drips from above ...
Exhaust Valves - Right! The intakes are constantly cooled with gasoline, and we stick out in the very hell. So there is no one to help us, and the hydriks also beat with all their might, especially on the cold ...
Oil seals - YES! YES!
Intake Valves - Uh-huh! We cool off with petrol. Here they will put the phase adjustment on you, then we'll see how you will dance.
Hydraulic lifters - Guys! We are here with the last of our strength! You try to release the coked spring - go wild!
ECM - Calm down! Since you are all such sissies, I am making an adjustment! Are we going to go? CCM (climate control unit)?
SSM - Leave me a bit of power, it should be cool in the cabin.
Coolant Temperature Sensor - Knock It Out! We’ll all die here right now, and he’s all about stupid things to think about! And tell the fan not to let it slip, otherwise it's hot here.
ECM - I will turn off the condo, but we'll wait with the fan. Here, when you show real numbers, then we will add power to it.
BCM (ABS) - Sorry to interrupt, but we have a speed spread on the front axle. Haldex needs to be tightened up.
ECM - I'll figure it out without you! I also found an adviser! Haldex had passed out a long time ago, and by the way, before his death, he complained that you were clogging up the entire network and not letting signals through to him. I have everything fixed - where, who and with whom! Lana, report back when these speeds equalize...
We work, we work! ETM (throttle control unit), what is the throttle opening angle right now?
ETM - Like 36%...
ECM - What does LIKE mean?
ETM - Well, one sensor shows 38, and the other jumps from 33 to 35, but I still had to adapt, after complaints from Lambda ...
ECM - Okay, did you get the signal for an additional 53% open?
ETM - No, nothing came
ECM - How did it not come? I sent it to you half a second ago.
ETM - Well, there is nothing
ECM - Why are you silent then? Then I redirect the analog signal directly to you from the gas pedal, work on it
ETM - Oh ... is it for me to think adits myself? I can't think as fast as you...
ESM - Well, who else? If you screwed up the digital connection. It will be necessary by the way in the next working cycle to check what kind of garbage.
So, the ETM has started working, we are counting the air consumption, revolutions, load, taking into account the temperature ... The nozzles have gone, the coils have tensed ... we are not in a hurry, we are not in a hurry: 1-2-4-5-3, 1-2-4-5- 3...
Lambdas - FUCKED at all? We have a flood here!
ECM - Yes? Then I see that the crankshaft sensor reacts somehow strangely. Okay, don't yell! I will check it in the next 1000 cycles, but you yourself understand that any bumps in the road can affect it. Therefore, if I don’t make sure for sure, then I won’t officially indicate misfiring!
Brake pedal - STOP!
ECM - Everyone listen! Rota stop - one, two ...

Do you understand what I mean? You can hardly get by without a specialist. Well, if you yourself want to understand something, then you need to describe everything in more detail, preferably with numbers, and give more detailed information about the car ...

Can a malfunctioning fuel pump cause excessive fuel consumption?

Engine Basics

Essentially, an engine is a chemical transformation device. It uses the energy in the fuel to create pressure and heat, which pushes against the pistons to create mechanical power. This process occurs as a result of combustion, when you mix fuel and oxygen in the correct proportions and ignite it.

Fuel system

The fuel pump not only pumps fuel, as its name indicates, it also creates pressure in the fuel line. In a carbureted engine, high pressure is not required, since fuel is supplied to the carburetor's float chamber, and from there to the engine. Fuel injected engines require much higher pressure. Low fuel pressure results in poor fuel atomization and carburetion resulting in reduced engine power. In response to a reduction in engine power, the driver usually gives more gas to compensate for this, and this already leads to an increase in consumption.

rich and lean mix

Both rich and lean mixtures cause increased consumption, but for different reasons.
A rich mixture causes increased fuel consumption because more gasoline enters the combustion chamber than can be burned. That is, part of the gasoline simply "flies into the pipe", into the exhaust in this case.

With a lean mixture, a drop in engine power is observed, which ultimately also leads to an increase in consumption. However, this happens due to the fact that the driver presses harder on the gas to compensate for the lack of power.

Possible causes of malfunction

There are a lot of possible causes of a malfunction in pumps, but let's try to highlight the main ones:

1. Low quality fuel and the presence of water in it. Water is the enemy of fuel pumps, and it gradually destroys them. Also, water compresses much worse, which also negatively affects the life of the pump.

2. Clogged fuel filter - A clogged fuel filter creates excess pressure upstream of the filter, which reduces pump performance and shortens pump life.

3. A faulty fuel pressure regulator, as well as a clogged fuel filter, creates problems for the pump and shortens its life.

4. Use of alcohol-containing fuel with pumps not designed for this.

5. Poor quality of the fuel pump, plastic elements inside the pump in cheap pumps often fail.

In our store you can always choose high-quality pumps from world-famous time-tested manufacturers.