The old Buick is unstable in the morning when the car is cool, and the car is just hot, what s going

Hello, it is generally caused by too much carbon deposition in the oil circuit, and the landlord can make a reference.

The cars are all the same, and the idle speed is 1200 in the morning, and it will be 8000 after a while of preheating.

The main reason is that the engine idle is unstable due to excessive carbon deposits on the throttle.

1. Diagnosis method for idle switch not closing: turn on the air conditioner when idling, and turn on the steering wheel The engine speed does not rise, which can prove to be this fault. Troubleshooting:

Adjust, repair, or replace the throttle position sensor. 2. Idle control valve (ISC) fault diagnosis method: check the actuation sound of the idle control valve, if there is no actuation sound, the idle control valve is faulty.

Troubleshooting: Clean or change the idle control valve, and use a special decoder to set the idle speed basically. 3. Diagnosis method of air leakage in air inlet pipeline:

If you hear a snort of a leak in the intake pipe, it is a sign that the intake system is leaking. Troubleshooting: Find leaks, reseal or replace phase parts.

4. The injector is dripping or clogged.

Diagnostic method: Use a stethoscope to check whether the injector makes a "click" actuation sound or measure the fuel injection volume of the injector, if the injector does not make a sound or the fuel injection volume exceeds the standard, the injector is faulty.

Troubleshooting: Clean the injectors, check the amount of fuel injected into each injector and confirm that there is no clogging or dripping.

Go to the 4S shop and check it and clean the idle motor.

The problem of oil quality, the oil products in the country are not very good for a while, plus the black box operation of the gas station, you add 97 oil is equivalent to 93. There are more impurities in the oil, which causes the valve to occasionally close loosely, so it will cause the engine to shake. Other than that.

When the car first started in the morning, the oil sprayed by the fuel injector was absorbed by the carbon deposit, resulting in insufficient oil supply to the cylinder body, and there would also be a phenomenon of shaking, you can clean the carbon deposit, the method is to open the cylinder head for cleaning, the disadvantage is that the cost is high, but the cleaning is clean and thorough. Another way is to add carbon cleaning liquid, but there are many types of cleaning solutions on the market, so choose a good one!

The main reason for the instability of the car idling is the leakage of the intake manifold, when the air, gasoline vapor and combustion exhaust gas that should not enter enter the intake manifold, resulting in the mixture being too thick or too thin, causing the car to idle unstable.

1. When the air intake manifold leaks, when the air, gasoline vapor and combustion exhaust gas that should not enter enter the intake manifold, the mixture is too thick or too thin, causing the car to idle unsteadily. The car owner can identify whether there is an air leak in the intake manifold by opening the engine compartment cover and removing the air filter of the throttle.

Start the car and block the throttle with your hand (if the car stalls after the blockage, it means that there is no air leak, if it is not stalled, it means that there is an air leak somewhere). If there is no flameout, there is no need to rush to extinguish the flame, at this time, check the nearby pipes to see if there is any inhalation, if there is inhalation, it means that it is leaking.

2. Excessive carbon deposition on the throttle: excessive carbon deposition in the throttle and the surrounding air intake, and the change in the cross-sectional area of the air channel, make the control unit unable to accurately control the idle air intake, and also cause the mixture to be too thick or too thin, resulting in unstable car idling.

3. Failure of the actuators of the intake system: There are many actuators of the engine intake system, such as throttle motors, idle stepper motors, duty cycle solenoid valves, air flow meters, intake pressure sensors, etc., which cause the idle speed of the car to be unstable.

4. Fuel system failure: Fuel injector blockage, fuel filter blockage, fuel pump filter blockage, fuel pressure regulator failure, oil return pipe blockage and other faults will lead to incorrect fuel injection, resulting in over-concentrated or over-thin mixture, resulting in unstable car idling.

5. Ignition system failure: ignition module failure, incorrect spark plug clearance, spark plug electrode ablation or damage, high voltage line resistance and other faults lead to ignition spark energy decline or misfire, resulting in unstable car idling. If the car has an unstable idle speed, then it should be dealt with as soon as possible, knowing that the engine is no longer at the ideal idle speed, and the fuel economy and environmental protection will deteriorate.

If the engine is unstable when the engine is running cold, it is easy to stall, but the idle operation is basically normal after the hot car, and the reasons are usually as follows:

When the additional air valve is not opened or the opening is too small, the idle speed of the engine is too low when the engine is cold, resulting in unstable idling.

2.When the engine is cold, the idle control valve is faulty, and the opening is too small, so that the idle speed is too low when the engine is cold, resulting in unstable idling.

3.The water temperature sensor is faulty, so that the engine computer does not increase the idle speed and thicken the mixture according to the engine temperature when the car is cold, resulting in unstable idling.

4.The injector is poorly atomized or partially blocked, which makes the quality of the mixture deteriorate or the amount of fuel injected is too small under the idle condition of the cold car, resulting in the mixture being too thin and causing the idle speed to be unstable.

1. Too much carbon is deposited on the throttle and air flow meter.

Throttles and air flow meters are still relatively easy to get dirty. Most cars today are electronic throttles. Small amounts of carbon deposition may affect them. Excessive carbon deposition on the throttle may cause the fuel throttle to jam, power drop, unstable idling, etc.

2. Excessive carbon deposition in the cylinder combustion chamber and piston!

There is too much carbon deposit in the combustion chamber of the cylinder, which will have a certain adsorption effect on the gasoline! So it will take a little longer for the ignition to start!

In addition, excessive carbon deposits will be mainly formed on the valve and piston rings, which will indirectly lead to insufficient cylinder pressure! A cold start can easily lead to unstable idling, and a warm car will eliminate these symptoms!

Remind everyone to pay attention to the carbon deposition cleaning and throttle cleaning of the engine when repairing. The more kilometers you run, the more you know how important it is!

There are several reasons why the idle speed of the cold car is unstable when it starts:

1. Caused by excessive dirty throttle;

2. Caused by the failure of the oxygen sensor;

3. The water temperature sensor is faulty;

4. Caused by excessive carbon deposition in the spark plug.

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After this phenomenon occurs, this is mainly because the throttle is dirty, and the throttle valve appears slightly stuck after the cold car starts, and this phenomenon will appear, and the throttle needs to be cleaned, and the computer can match it after cleaning. This can be solved, if there is still this phenomenon after matching after cleaning, then you need to check the spark plug, check that the engine cylinder has more carbon, and it also needs to be cleaned.

The vast majority of this may be the throttle valve needs to be cleaned, the requirements for the air-fuel ratio of the engine are relatively high when the car is cool, the lack of air intake will cause the mixture to be too thick and difficult to burn, and the requirements are relatively low when the car is hot, so it is better to start some, you can first consider washing the throttle to observe it, I hope it can help you.

Volkswagen's common problem, the cold car throttle is not sensitive, when stepping on the accelerator, I feel that the car is very reluctant to go, and the front suspension makes a weird sound, but after the car is hot, these problems are gone

1. Too much carbon deposition in the throttle and air flowmeter is still relatively easy to get dirty, and a little carbon deposition may affect it, and excessive carbon deposition in the throttle will cause the accelerator to be stuck, the power will drop seriously, and the idle speed will be unstable.

2. There is too much carbon in the combustion chamber of the cylinder, which will have a certain adsorption effect on gasoline, and too much carbon will be formed, most of which will be formed on the valve and piston ring, which will indirectly cause the cylinder pressure to be insufficient, and it will be easy to idle and unstable when the cold car starts, and the hot car will be good.

How to prevent cold starts and maintenance of cars in winter:

1. Check whether the battery shell is leaking electrolyte. If there is a leak, the battery should be replaced; If there is no leakage, the oxide on the surface of the battery and the poles of the battery should be cleaned with hot water, but care should be taken not to allow water to enter the inside of the battery through the vents. After the water is dry, it is best to use sandpaper to polish the contact surface between the pole and the joint, and tighten the fixing screws on the joint to ensure that there is enough current to pass through when starting.

2. Check the voltage of the battery. The method is: when the engine temperature is normal and the starter is in good technical condition, the engine can be started smoothly for several consecutive starts, indicating that the battery is in good condition and the voltage is normal.

If the engine speed gradually decreases with each start, or the engine barely starts, it means that the voltage of the battery is in a state of loss and should be charged.

1. Introduction to air flow meter.

The role of the air flow meter.

The air flow meter measures the amount of fresh air entering the engine intake manifold and the intake air temperature, and the ECU uses this information to make injection corrections, smoke limits, and EGR opening control.

2.Installation location.

The sensor is mounted on the engine intake duct and at the rear end of the air filter.

3.How it works.

The principle of an air flow meter.

The air flow sensor is to integrate some electronic components on a ceramic substrate, when the engine is working normally, the diaphragm is first heated, and the fresh air flows through the sensor will take away part of the heat, at this time the ECU will control the Wheatstone bridge on the diaphragm to supplement the diaphragm, which will cause a change in the electrical signal, when the signal is transmitted to the ECU, the ECU will calculate the air intake according to this change.

The principle of the air temperature sensor.

The inlet air temperature sensor is a negative temperature coefficient resistor, when the inlet air temperature changes, the resistance value of the resistor will change, causing a change in the signal voltage at the ECU terminal, and the ECU calculates the inlet air temperature based on this change.

Determination of the direction of the airflow.

There is a same temperature resistance at both ends of the hot film of the air flow meter, and when the air flow flows through the hot film, it will take away part of the heat, so the temperature at the front end of the hot film is lower than the temperature at the rear end, and the ECU judges the direction of the air flow according to this signal!

4.Wiring diagram of an air flow meter.

5.Control policy.

The ECU will monitor the working condition of the air flow meter at all times, and when the ECU judges that the air flow meter is faulty, it will take corresponding control, as follows.

The engine mil light is lit, the EGR system is withdrawn from work, and the exhaust gases will no longer participate in the system work;

The engine speed will be limited to a certain speed, and the power will be limited;

When the air flow meter fails, the engine start is not affected and can be started normally;

Second, the detection of air flow meter:

Fault codes related to air flow meters.

It is recommended that you check the battery, valves, etc., to see if the battery capacity is reduced, especially the low temperature cold car start, whether the valve of the oil circuit is blocked, and the oil is not good, the low temperature cold car start oil can not be fully burned, so the power reduction causes the idle speed to start unstable!

First of all, the idle speed value set by each brand is different. Second, don't get into the habit of getting into the heat of the car. For a normal car, the time from getting on the car to leaving the car should not be more than one minute.

Idle speed. Instability can be due to the following reasons:

1. The engine has serious carbon deposits.

When there is too much carbon deposits inside the engine, a cold start.

The gasoline sprayed by the fuel injection head will be absorbed by the carbon deposit in large quantities, resulting in the mixture of cold start being too thin, making it difficult to start, in this case, only when the gasoline absorbed by the carbon deposit is saturated, it is easy to get on the car, and the gasoline adsorbed on the carbon deposit after the car will be sucked into the cylinder by the vacuum suction of the engine for combustion, and the mixture becomes thick, and the combustible mixture of the engine is dilute and thick, causing idle shaking after cold start.

2. Throttle.

and excessive fouling in the inlet tract.

The excessive carbon and dirt deposits in the throttle valve and the surrounding air intake, and the change in the cross-sectional area of the air channel, make the control unit unable to accurately control the idle air intake, resulting in the mixture being too thick or too thin, and making the combustion abnormal.

3. Individual spark plugs.

The spark plug spark caused by the fault is too weak.

Spark plugs also accumulate carbon.

Carbon deposits can be cleaned to restore spark plug activity, but some spark plugs are nearing the end of their useful life and their performance will be reduced. The spark plug spark on the individual cylinder is weak, which will affect the performance of the car, and the spark plug failure will cause the car to have the symptoms of "lack of fire", but the spark plug of the individual cylinder will have idle instability symptoms if there is a slight fault.

4. Fuel pressure failure.

If the oil pressure is too low, the atomization state of the fuel injected from the injector is poor or the fuel injected is linear, and only oil droplets are sprayed in serious cases, and the amount of fuel injected is reduced to make the mixture too thin; The oil pressure is too high, and the actual fuel injection volume increases, making the mixture too concentrated.

5. Failure of various parts.

Leakage of intake manifold or various valves, failure of fuel pressure, low oil pressure, failure of ignition system, etc., can also cause engine idling instability.

If the idle speed is normal when the engine is running cold, the idle speed is unstable after the hot car, the idle speed is too low or the engine stalls, the reasons for the failure are usually as follows:

1) The idle speed adjustment is too low.

2) The water temperature sensor is faulty.

The idle control valve is faulty.

4) The spark plug is not working well.

5) The injector is working poorly.