For normal ICE operation a certain composition of the air-fuel mixture is required, in a ratio of 1:14, 1:16. That is, for the complete combustion of one liter of gasoline, 14-16 kg of air is needed. If this proportion is observed, the engine runs stably, in economy mode and with full power output. If the composition of the mixture is violated, problems with work begin. power plant. One of the reasons for changing the composition of the fuel mixture is additional air in the connections. In this case, the mixture becomes leaner due to additional air, which immediately affects the operation of the motor.

Malfunction symptoms:

Problems with starting (the proportion of fuel becomes smaller, the mixture becomes leaner, and for a cold start it needs to be enriched);

Reduced power and increased fuel consumption;

Self-diagnosis gives errors on the operation of the engine: misfiring, malfunction of oxygen sensors.

How to find a suction point?

In most cases, excess air appears at the junction of the joints of various parts or due to the formation of cracks in the parts themselves.

Most often, suction is observed in the following places:

Knot throttle valve;

Hose with vacuum booster;

intake manifold seals;

In corrugation from air filter to (the branch pipe itself or the connection points);

x / x regulator;

Gaskets under the carburetor or through its elements (quality screw, starting diaphragm, damper axles and their ovality, economizer membranes);

Fuel injector rings;

When the adsorber valve is jammed.

Diesel air intake

Most often, a malfunction appears in the connections between the fuel tank and the pipe connections, as well as between the filter and the injection pump. On modern diesel engines, suction is caused by a change in the design of the joints.

So in the old motors, the connections were made of brass and were essentially “eternal”, and in the new type of engines, the brass was replaced with plastic, the service life of which is an order of magnitude lower. Plus to this winter period cracks may appear on the plastic, especially for cars with a mileage of about 150-200 thousand km.

The main causes of the malfunction:

Leakage of pipelines (supply or return);

Clamps malfunction;

Deterioration of connecting hoses;

Through the cover of the fuel pump or its drive shaft.

The difficulty in finding a fault is due to the fact that there is no leakage in leaky connections, since the external pressure is higher than the internal one in the pipeline.

Signs of suction on diesel engines:

Difficult morning start of the engine;

Unstable x / x;

The engine stalls while driving.

Causes of malfunction:

power plant;

Gasket damage.

Problems on diesel and gasoline engines often caused by damage to the seal between the head of the block and the intake manifold, or the behavior of the connection plane on the body of the manifold itself, which is quite difficult to determine visually.

Ways to determine the points of air leakage:

close air flow. The corrugation is removed from the air filter, the engine starts. Next, the pipe is closed by hand and the motor should stall, and the corrugation itself will shrink. If the engine is running, and the corrugation is unclenched, then there is excess air;

Spilling joints. With the help of a medical syringe filled with gasoline, all existing joints are processed. If liquid enters the place of suction, the engine speed will either fall or increase. When working, make sure that gasoline does not get on the electrical wiring. You can also use WD-40 or any carburetor cleaner for this purpose.

intake manifold and throttle;

Branch pipe between IAC and valve cover;

Between DMRV and IAC;

intake manifold and block head;

nozzle rings;

Clamp connections.

When contacting a car service, mechanics can determine the location of the malfunction using a compressor, applying pressure through the spark plug hole, and also using a smoke generator, by introducing smoke into the manifold. Smoke will appear in leaky places.

The advantage of using smoke is that it will show any leaks where it is almost impossible to get close with a syringe to spill the compounds.

You can make a smoke generator with your own hands by watching, for example, one of the video clips on the Internet.

Prevention measures

Periodically inspect all connections, hoses, pipes, as well as the reliability of the fastening clamps. If the above signs of air leakage appear, without delay, find problem areas and troubleshoot.

An air bubble entering the heart of a person leads to death. The air that got into the heart of the car - the engine, leads to less tragic consequences, but is also fraught with big troubles, can stop it forever.

Just as a normal person constantly monitors the state of his body, a normal motorist constantly monitors the “health” of his iron comrade. The “organism” of a car, of course, is less complex than a human one, but there are many reasons for various malfunctions and failures, especially if the car is no longer young.

This is despite the fact that such a problem, such as, for example, air leakage, can also be found in a completely new car. Of course, this is rarely inherent in expensive modern foreign cars, but domestic cars quite often suffer from such a "disease".

The cause of suction is often the units that supply the fuel-air mixture to the engine, which, of course, can affect its operation. For example, it may be that the car starts, but after a while it stops responding to pressing the accelerator pedal. Further, as a rule, a deepening of the problem follows, when the engine can be started only with large and repeated efforts of the starter.

If the car does not start at all - see if fuel is getting into the cylinders. This is quite simple to do - you need to see if there is at least a slight smoke from exhaust pipe when trying to run. Of course, it is not easy to do this yourself, but anyone, even a child, can help with this.

A modern car is not just a means of transportation, but also a very complex mechanism, even a group of mechanisms, and therefore there can be many reasons for a violation of the fuel supply to the engine. The most common cause- malfunctions in the fuel-conducting line. This may be hose wear, and a mess with fuel pump, filter with poor quality or worn seals, corrosion fuel pipes,. This problem can also suddenly appear after car repairs, when careless or simply unskilled "specialists" have broken the tightness of the connections. individual elements fuel system.

Air enters the engine cylinders in different ways. Perhaps from the atmosphere, this occurs in cases where air can be sucked in from the outside, and there may be penetration from the internal space of the engine. Be that as it may, in any case, this shows that there is a violation of the tightness of the system in the fuel system and this requires immediate elimination.

Air leaks are just the beginning of problems that can lead to engine failure. Air entering the combustion chamber does not allow the working mixture to fill the volume in the right amount - the burning time of the mixture increases and, accordingly, the engine loses power when trying to increase the load. The driver at this time may notice interruptions in the engine and dull sounds escaping from the exhaust pipe, you can also notice that the engine overheats too quickly. Overheating is the cause of the ignition of the fuel mixture even before it enters the combustion chamber, and this will inevitably lead to engine failure if not responded to in time.

In the event of a malfunction, as usual, you can try to fix the breakdown on your own, but this is only if you have certain skills. If there are none, then it is better to contact specialists who will conduct a thorough diagnosis and competently repair the malfunction.

Consider one of the most simple ways how to check air leak intake manifold injection car without any material costs.

This method is not a panacea, but is the simplest and most effective in finding air leaks in the intake manifold.

As you know, during engine operation, a large vacuum is created in the manifold. At idle, the pressure in the manifold drops to 30 kPa, and atmospheric pressure is usually around 100 kPa.

Such a pressure difference forces the air from outside the collector to get inside the collector by all available paths. If he succeeds, then you should not even think about the normal operation of the engine - all kinds of jerks and dips, as well as excessive fuel consumption are provided!

So our task with you is to find all these “accessible ways” for the penetration of unaccounted air into the intake manifold.

The main symptoms of air leakage are:

• increased turnover idle move
• floating idle speed
• inadequate response of the engine to pressing / releasing the gas pedal
• increased fuel consumption

The simplest and most effective method of checking for air leaks into the intake manifold is to fill the manifold with low pressure smoke. And if there are leaks in the collector, then they can be seen by the smoke coming out of them.

For these purposes, smoke generators are used. But not all service stations have such equipment, and it is somehow expensive to buy it for yourself to use it once every two or three years. How to be?

You can do as I did - collect a free smoke generator "on your knee" from plastic bottles.

In general, I was standing at the checkpoint the other day. And in order not to waste time in vain, I decided to bring to life an idea that had been worrying me for a long time - to assemble a simple smoke generator to check the intake manifold.

From a suitable tool, I found only a small knife and a triangular file without a handle.

A one and a half liter plastic bottle was also freed from water down the throat. I also bought a half liter bottle of a certain drink, which was quickly drained by my daughter

First of all, I cut a large and a small bottle into two parts. I threw away the top of the small bottle. In total, there are two lower parts (small and large) and one upper. I think it's understandable.

Removed the hose from the crankcase ventilation valve. I made a hole in the bottle cap with a file so that the removed hose entered it with effort. I screwed the top of a large bottle onto the cap. Here is a picture

From a different angle

Everything turned out tight

Then he dug a hole in the bottoms of both lower parts. In the smaller one, under the diameter of the cigarette, and in the upper one, under the diameter, the hoses from the compressor for pumping the wheels.

He shot a cigarette from the driver of a neighboring car, lit it and inserted it into the hole of a smaller bottle, and shoved the whole thing upside down into a large bottle

I put it all in the top of the bottle and connected the car compressor

Here is a general view of this constructor

When foreign air enters the carburetor, the fuel mixture entering the car engine cylinders is depleted. The share of gasoline remains the same in it, but the share of air increases significantly. Such a composition simply does not ignite or ignites with difficulty and for a short time.

Therefore, the engine may not start at all (as well as), it may be possible both when starting off and in motion.

If the suspicion falls on the leakage of connections, seals and hoses, then it is necessary to check them as soon as possible.

General check for "suction" of foreign air into the carburetor

There is one effective way check if foreign air is being sucked into the carburetor. It is necessary to remove the air filter housing from it, start the engine, let it run for a while, and then cover the carburetor from above with your palm.

In the event that the engine continues to operate with blocked air supply channels, an attempt should be made to search for places of this very “leakage”.

If the carburetor has stalled, look for the cause of the malfunction in something else, and not in the "suction" of extraneous air. Of course, this check does not claim to be exceptionally accurate, but in some cases it can help.

Possible places for foreign air to enter the carburetor

- Check how tightly the carburetor solenoid valve is wrapped or an idle fuel jet holder inserted instead.

For a number of reasons, they sometimes turn out and even get lost. It is necessary to wrap the valve or holder, and if the engine began to work normally, by wrapping or unscrewing the solenoid valve, we achieve stable idle speed.

The fuel jet holder (on a number of carburetors it is installed instead of the solenoid valve) should be wrapped with a little effort.

solenoid valves for carburetors 2108, 21081, 21083 Solex and 2105, 2107 Ozone

It is also necessary to check whether the sealing rubber ring on the solenoid valve is damaged.

- Check the presence and condition of the rubber sealing ring on the screw "quality" of the fuel mixture.

In the image, as an example, the screw for adjusting the "quality" of the fuel mixture at idle speed of the carburetor 2107 "Ozone" with a rubber o-ring.

screw for adjusting the "quality" of the fuel mixture of the carburetor 2105. 2107 Ozone

- Check the tightness of the vacuum hoses

- From the ignition distributor (distributor) to the carburetor.

— From the vacuum brake booster to the intake manifold.

- Crankcase ventilation hose It is necessary to make sure that they fit tightly on the fitting, that there are no cracks, cuts, punctures and abrasions.

Clamp the hoses in turn near the carburetor fittings, and try to start the engine. If the "suction" of air is blocked in this way, the engine will work normally. In the image of the place of the probable "leakage" of extraneous air into the carburetor 2108, 21081, 21083 Solex.

places of probable “sucking” of extraneous air into the carburetor 2108, 21081, 21083 Solex cars VAZ 2108, 2109, 21099

- Check the tightness of the gaskets under the carburetor and intake manifold

If the breaks are not visually visible and the whistle of the intake air is not audible when the engine is scrolled by the starter, then we try to tighten the nuts of the carburetor and intake manifold. Tightening torque 13 -16 N.m - carburetor nuts, 21 -26 N.m intake manifold nuts. That is, it is not necessary to pull hard, especially on a warm engine.

The tightening did not help, we remove the carburetor and change the gaskets, since they are not expensive.

It is possible to cover the checked connections with soap foam or VD-40 liquid, in the place of "suction" a window is formed in the soap foam.

As a result of excessive tightening of the carburetor mounting nuts or for any other reason, the carburetor seating plane may be deformed and then excess air will be sucked in for this reason. To identify this defect, it is necessary to put the carburetor removed from the engine on a deliberately flat surface, for example, a sheet of thick glass and see if there is a gap between the lower plane of the carburetor and a flat surface. There shouldn't be any gaps. There are two ways out either to grind the landing plane of the carburetor or put an extra gasket under it.

Not only the maximum engine power depends on the composition of the air-fuel mixture (its “quality”), but, what is sometimes more important, its controllability - excess air entering the intake tract can cause the engine to stop at the most inopportune moment. Let's say you're leaving a secondary road for a main one. Estimated the distance to the flow of cars moving along main road- and when you try to “take off”, the engine stalls ... Damage to the car from a side impact may not be the most serious consequence in this case.
What could be the symptoms of air leakage in the intake manifold and “how to deal with them” is the topic of this article.

Insignificant "surpluses" of air may not manifest themselves in any way, since they are not able to greatly change the composition combustible mixture, and only engine diagnostics can identify them.
But with major damage to the intake tract, symptoms of air leakage can be:

The first symptom of air leakage in the intake tract is the unstable idling of the engine.

• unstable operation of the engine at idle, up to its stop;
• dips during acceleration, and at hard pressing on the “gas” pedal, the engine may again stall, especially at the beginning of the car;
• increase possible operating temperature engine due to its running on a too lean mixture.

It should be noted that the uneven operation of the engine is “smoothed out” at medium and high revs, we can only note a decrease in the traction qualities of the engine.

How can "extra" air enter the cylinders?

Excess air entering fuel mixture possible not only directly through a violation of the intake manifold gasket, but also through the parts associated with it. Let us consider in more detail the possible places of violation of the integrity of the intake tract for the carburetor and injection engines separately.

carbureted engine

Possible places for air leakage at the intake

Possible "weaknesses":

A common cause of air leakage is deformation of the "sole" of the carburetor when the carburetor is tightened on a hot engine.

• gasket for the carburetor;
• carburetor diaphragm. Basically, these are the diaphragms of the trigger and the actuator of the shutter of the second chamber - not all models have the latter;
• vacuum hoses for controlling the advance angle (goes to the distributor), for all kinds of pneumatic valves; also sometimes the carburetor fittings themselves are loosely inserted into the body at the factory;
• deformation of the "sole" of the carburetor; a very common cause of suction, caused by the fact that the carburetor is tightened on a hot engine.

injection engine

Suction is possible through:

• nozzle seals;
• receiver gasket;

Generalization

In addition, for both types of engines, suction is possible through a damaged hose of the vacuum brake booster, as well as through the seal of its valve (fitting) inserted into the booster housing. Moreover, many motorists ignore the fact that if the free play of the brake light switch (“frog”) is incorrectly set, the correct operation of the amplifier itself can be disrupted, as a result of which the air intake from it will be “wrong”, which will cause excessive air intake into the intake collector. The correct setting of the "vacuum" is also affected by the amount of protrusion of its rod from the body. The most unpleasant thing in this situation is that the air leak "through" vacuum booster not detectable from the outside during inspection.

Troubleshooting

You can easily and clearly determine the air leakage in the intake manifold with a smoke generator.

The most accessible way to find air leaks in the intake manifold is a visual inspection. Cracks and ruptures in air hoses can also be seen with the "naked" eye. You can also check how tightly the parts are connected to each other. It often happens that during the repair, for example, the nuts of the carburetor or other components were not tightened properly.
If there are no visible causes of malfunctions, then it is very effective to spray from a can of "Quick Start" compositions made on the basis of ether along the joints of the parts. The procedure must be carried out with the engine running. The ether that has entered the collector through the slots will cause changes in the operation of the motor - its speed should increase for a short time.
Finally, the question of how you can detect air leaks in the intake manifold is easy to resolve if you have a smoke generator. With its help, the search for places of leaks does not present any particular problems. Having “pumped up” the intake tract with smoke, you can visually observe where the integrity of the intake system is violated - in this case, it is better to use a blue lamp (flashlight) - it becomes more noticeable in its light.

Elimination of air leakage in the intake manifold

When repairing the intake manifold, do not apply force to the sensors - excessive force can damage them.

Repair, basically, is reduced to the replacement of gaskets, seals and vacuum hoses. Moreover, it is not necessary to restore cracked hoses with a sealant - its excess, once in the air path, can cause blockages.
When repairing, remember that you should not put effort on trying to check if some of them are jammed. This is especially true of the idle speed controller - it is just installed in the intake tract. By pressing on its core, you run the risk of completely spoiling the regulator, which is a stepper motor.
And finally - keep in mind one more important point. Sometimes air leakage "from the side", although it does not affect the operation of the engine in any way, can lead to very unpleasant consequences. We are talking about cases where air enters the manifold, bypassing the air filter. For example, if that part of the filter housing is split, from which the dust-free air enters the collector. It happens that a person drives for a long time with a fair crack in the filter housing or in the corrugated air intake hose from the filter to the throttle body. At the same time, the idle speed and engine power will be normal, but you risk greatly reducing the resource of the motor itself.
An automobile magazine once published an article about an experiment carried out by a group of inquisitive people - they drove through the desert without an air filter. The engine completely "ended" without even passing 100 km. Therefore, look carefully!