What are the common fault phenomena of engine mixture?

After driving many cars for a period of time, there will be a phenomenon of "backfire" or "fire", what is going on? Generally speaking, these two situations indicate that there is a problem with the mixture. If the mixture is too thin, it will be "tempered", and if it is too thick, it is easy to "fire", how to solve the problem of too thick or too thin engine mixture?

Let's learn together!

Too thin of the mixture slows down the combustion rate and ignites the mixture in the intake state, resulting in a "tempering" phenomenon in which the mixture burns in the intake pipe.

The mixture is too concentrated and will cause incomplete and insufficient combustion, and the high-temperature exhaust gas containing more combustible gas will be burned again in the exhaust pipe after it enters the exhaust pipe, and the exhaust pipe is formed to "discharge".

There are three main reasons for the backfire of automobile engines:

1. The mixture is too thin

The oil circuit failure is mainly caused by too little fuel injection in the injector, and the main reasons for too little fuel injection in the injector are: the oil pressure is too low; The injector is clogged. The failure of the air intake system is mainly caused by excessive air intake, and the main reasons for excessive air intake are:

The sensor that controls the amount of air intake fails; The intake manifold is leaking.

2. There is a problem with the ignition system

Another reason for the failure of the car engine tempering gun is the insufficient ignition energy (too much resistance of the high-voltage line; Damage to the ignition coil; The power supply voltage is insufficient) or the spark plug is faulty.

3. Other reasons.

The ignition advance angle is too large; The CKP gap is not suitable; CKP loosening; The temperature sensor is damaged; engine load; ECU damage, etc. Among them, the ignition advance angle is too large, which will cause the combustible mixture to be ignited prematurely, and the expansion pressure generated by gas combustion will hinder the upward movement of the piston, resulting in the reduction of engine power, the increase of fuel consumption, poor idling, and sometimes even the crankshaft reversal, torsion, etc.

How to check and solve it? Mainly start with the following 6 points:

When starting the engine, pull out the choke knob first to close the choke door, if the engine can start, and the operation is normal, it means that the engine mixture is too thin.

Check and adjust the oil plane height of the carburetor float chamber.

Check whether there is blockage and leakage in the engine oil circuit, whether the gasoline pump and gasoline filter are normal, and the gasoline filter should be cleaned or replaced if the gasoline filter is blocked.

Check and adjust the oil supply of the carburetor main bore.

Check if the oil line on the gas tank is blocked.

Check the intake and exhaust manifold gaskets for loose, leaking, or damaged.

The engine mixture is too thin and generally manifested as not easy to start, unstable idling, weak driving, unable to raise speed, poor high-speed performance, etc., I hope it will be useful to you.

Exhaust pipe discharge. The exhaust pipe is discharged, and the fault code and data flow show that the mixture is too thin. Under normal circumstances, too thin mixed steam will cause backfire in the intake pipe, and too thick mixed steam will cause the exhaust pipe to discharge.

However, the evolution of things always follows the law of "from quantitative change to qualitative change". For example, the difficulty of starting caused by low fuel pressure was originally a case where the mixture was too thin, but when the spark plug was removed and checked, it was found that the electrode was wet, indicating that the cylinder was "flooded", giving people the impression that the mixture was too thick.

Before finding the cause of the mixture being too thin, it is necessary to say when it is "too thin", otherwise some people think that as long as it deviates from the theoretical proportion, it is too thin. There are two types of evaluation of the degree of combustion: air-fuel ratio and excess air coefficient. In fact, in the actual operation of the engine, the excess air coefficient is in between, that is to say, the mixture "excites the pants to search for thin" is the norm.

Usually it is only when the excess air coefficient is exceeded that it is defined as "too thin".

<> in addition to this, like the failure of the inlet pressure sensor or air flow meter; Poor operation of the gasoline pump and low oil pressure can also lead to insufficient fuel supply and the problem of too thin mixture. In short, there are many reasons that can cause the problem of too thin mixture, but because there are various sensors to monitor it, you don't need to worry too much. However, if you hear the engine bang bang gun statement, it is difficult to increase the speed after starting, and when the engine is weak in acceleration, idle shaking, and easy to stall at the start, it is possible that the mixture is too thin, and it is necessary to pay attention to it.

In fact, the dilution of the mixture concentration is mainly due to insufficient oil supply, which is generally divided into two situations: the oil circuit outside the injector and the oil circuit inside the injector. The reasons for the insufficient oil supply to the oil circuit outside the injector are generally as follows: first, the gasoline filter (gasoline pump) is blocked by impurities (the filter screen is posted), or the oil pressure is not enough for the faulty workmanship; Second, there is a blockage in the gasoline pipeline or the oil pipeline is damaged; Third, the tubing joint is loose and leaking; Fourth, there is water in the gasoline or gas resistance; Fifth, the inlet and outlet valves of the gasoline pump are not tightly fitted.

When the mixture is too concentrated, due to incomplete combustion, a large amount of carbon monoxide and free carbon particles will be produced in the cylinder, resulting in carbon accumulation in the cylinder head, piston top, valve and spark plug, blue smoke from the exhaust pipe, and serious exhaust pollution. In addition, the carbon monoxide in the exhaust gas may also be ignited by the high-temperature exhaust gas in the exhaust pipe, and the phenomenon of "discharge" of the exhaust pipe occurs. In addition, due to the lower combustion rate of this mixture, the effective power will also be reduced and the fuel consumption rate will be greatly increased.

The reasons for this phenomenon may be that the engine is blocked, the oil pipe is cracked, the oil inlet of the engine is too dirty, the gasoline pump is badly worn, and the engine is not repaired all year round.

It may be due to the carburetor being cautious, or it may be due to insufficient adjustment of the main measuring hole, or it may be because the filter is too dirty, or it may be because the hole is blocked, or it may be because the oil pipe has cracks.

There is a problem with the fuel supply system, or the amount of fuel is insufficient, and there may be a lot of faults and cracks in the intake system, cold start difficulties, gasoline deterioration, carbon deposition problems, and so on.

It is very likely that the filter of the gasoline is clogged with hail. Or maybe the joint is loose. The tubing is damaged. The main quantity hole plug imitates the poor plug. These can lead to an over-dilute engine mixture.

Its slender head is that the filter is blocked, or the wide answer is that the oil pipe is also blocked, the oil pipe has air leakage, etc., and its prudence and wisdom show only these few situations, which can be checked one by one.

EFI mixtures usually do not need to be manually adjusted. Changfeng Cheetah Mitsubishi 4G engine throttle has a bypass channel that can be adjusted, which cannot solve the ,.. of engine exhaust pipe exhaust black smoke, shaking, and firing guns

The mixture is only one of the reasons, since the phenomenon of mixture is thick, it means that it has exceeded the correction limit of the computer, and the computer is powerless. In the case of more fuel and less oxygen, the mixture will be incompletely burned in the cylinder, and the spark plug will be polluted (blackened), resulting in poor ignition, forming a vicious circle, and affecting the instability of idle working conditions. Only by finding out the cause of the mixture concentration can we solve the fundamental solution to the instability of idling.

In addition, how to determine the detection of mixed gas concentration slag liter method and instrument is also very important, such as the method of common laughter, to see whether the exhaust pipe is black, to see whether the spark plug is black, the mixture gas concentration will appear like a liquid phenomenon, in fact, the high pressure fire is weak, this phenomenon will also occur, be careful not to misjudge; Reading the data stream with a detector has certain limitations due to the performance of the oxygen sensor itself; This method of measuring CO with exhaust gas analyzer and HC can also be measured at the same time is highly accurate, and according to the measurement results, the working condition of the engine can be comprehensively analyzed and the cause of the fault can be found.

The engine is judged to be under partial load. In this case, the ECU determines the amount of fuel injected based on the air flow meter and the crankshaft speed signal. At this time, the engine is working under idle condition, and the air intake is small, resulting in an over-concentrated mixture and an increase in speed.

When the ECU receives the "mixture is too thick" signal from the oxygen sensor, it reduces the amount of fuel injected and increases the opening of the idle control valve, which causes the mixture to be too thin. Reduces the rotational speed. When the ECU receives the signal of "the mixture is too thin" fed back by the oxygen sensor, it increases the amount of fuel injected and reduces the opening of the idle control valve, which causes the mixture to be too concentrated and the speed increases.

This repeatedly makes the engine idle unstable, and turning on the air conditioner, steering wheel, and headlights at idle will increase the load on the engine. In order to prevent the engine from stalling due to increased load, the ECU will increase the amount of fuel injected to maintain the smooth operation of the engine. When the idle contacts are disconnected, the ECU thinks that the engine is not in idle condition and will not increase the amount of fuel injected.

Causes the engine to idle unsteadily, shake, etc. 2. Idle control valve (ISC) failure.

The correct idle speed of the EFI engine is ensured by the electronically controlled idle control valve. The ECU adjusts the idle control valve according to the engine speed, temperature, throttle switch and air conditioning signals. When the idle speed is lower than the set speed value, the computer commands the idle control valve to open the air intake side channel or directly or directly increase the opening of the throttle to increase the air intake volume to improve the engine idle speed.

When the idle speed is higher than the set speed value, the computer will instruct the idle control valve to close the small inlet and fly side channel, so that the intake air is minimized and the engine speed is reduced. Due to oil pollution and carbon deposits, the idle control valve is sluggish or stuck, and the throttle valve is not closed properly, so that the ECU cannot correctly adjust the idle speed of the engine, resulting in idle speed.

When the mixture is too thin, the combustion rate of the fuel decreases, and the combustion of a part of the mixture will be carried out when the piston moves to the dead center (referring to the four-stroke engine, that is, the combustion chamber space volume gradually increases under the condition of collapse). In severe cases, the combustion process will even be postponed until after the start of the intake stroke of the next cycle, so that the flame remaining in the cylinder is ignited by the open intake valve to ignite the mixture in the intake pipe and the carburetor outlet chamber, forming a tempering (also known as carburetor tempering) and producing a slapping sound.

This part of the mixture combustion not only releases relatively little heat that becomes mechanical work

There will be problems such as Wang Wuxian's lack of motivation; If the concentration of automobile mixture is too high, that is, there is less air and more fuel, there will be incomplete fuel combustion, increased fuel consumption, pollution trapping or increased mass purity or material emissions, pollution spark plugs, and it is easy to cause poor ignition, forming a vicious circle.

The fault phenomena of gasoline engine mixture too thin are:

The engine is not easy to start.

The engine is idle and easy to stall.

The engine power is insufficient, the car is weak, and it is very difficult to accelerate.

When the throttle is slammed on, the carburetor sometimes backfires or even stalls. Because the mixture is too thin, it will slow down the combustion rate and prolong the combustion time.

If the combustion concentration of the automobile mixture is too low, that is, there is more air and less fuel, and the car will have problems such as insufficient power; If the concentration of automobile mixture is too high, that is, there is less air and more fuel, there will be incomplete fuel combustion, increased fuel consumption, increased pollutant emissions, polluted spark plugs, and easy to make liquid brothers into poor ignition.

What will happen if the gasoline engine is too thin? The engine mixture is too thin and generally manifested as not easy to start, Chongzhou first idle unstable, weak driving, unable to raise speed, poor high-speed performance and other phenomena, I hope it will be useful to you.

The mixture is thick or the mixture is leaking, which will cause the engine to idle and shake, lack of power, weak acceleration, black smoke, fuel consumption, engine failure light will be on, and in serious cases, it will also report a multi-cylinder fire or fail to match the land car.

If the gasoline engine with a curved ruler is too thin, there will often be failures such as stupid high car driving frustration, engine shake, and obvious lack of power during the driving of the car.

If the concentration of the automobile mixture is too low, that is, there is more air and less fuel, and the car will have problems such as insufficient power; If the concentration of residual gas in the car mixture is too high, there will be less air and more base oil, which will cause incomplete fuel combustion, increased fuel consumption, increased pollutant emissions, polluted spark plugs, and easy to cause poor ignition.

The mixture is too thin and the idle speed is too high, and it is difficult for the engine speed to drop to the idle speed in a short period of time when the accelerator pedal is retracted quickly. At this time, if the spark plug is removed, you will find that the electrode color is white, which is a sign that the flammable gas mixture is too thin.

If the gasoline engine mixture is too thin, the car will shake, and then the power will be insufficient, or the car will turn off.

The gasoline engine mixture is too thin, which will affect the start, the running speed is unstable, and the intake pipe will be discharged in serious cases.

When the mixture is too thin, the combustion rate of the fuel decreases, and part of the combustion of the mixture will be carried out when the piston moves to the dead center.

There may be a lack of power, the speed cannot be increased when accelerating, and there will be certain difficulties when the car is ignited.

When the mixture is too thin, the combustion rate of the fuel decreases, and the combustion of part of the mixture will be carried out when the piston moves to the bottom dead center (referring to the four-stroke engine, that is, when the space volume of the combustion chamber gradually increases).