methods of car repair 1. from simple to difficult
when a car drives into a repair shop, we can learn the faults that need to be eliminated from the maintenance. For example: the engine fault light is on, the idle speed is unstable, black smoke is emitted, the refueling is weak, the automatic transmission does not upshift and the gear slips. We can choose the simpler one to solve, and when this problem is solved, other problems will be solved.
Example: A Jielong (four-cylinder engine) car, with engine trouble lights on, black smoke, easy flameout, difficult to start after flameout, and the odometer needle is in disorder.
because it is simple and targeted to retrieve the engine fault code, we will take this as a breakthrough. Call engine fault code: 1) Throttle position sensor fault. 2) Water temperature sensor failure. 3) The main computer is out of order.
first, we check the throttle position sensor, unplug the sensor plug, and measure the change value of throttle opening with a multimeter, which meets the standard value, and there is no fluctuation value, indicating that the sensor is fault-free. I also measured the wire harness from the sensor to the computer, and found that the resistance value was large. So clean up the wiring, strip off the general wiring harness section by section, until the general plug at the left rear of the engine room, and find that the wiring harness has traces of wear. Remove the assembly line of the wire, and find that several wires have been worn out. Clean the wiring harness, load the car, clear the fault code, and test run, and the above faults disappear.
because the car has been repaired in other repair shops, but the effect is not satisfactory, we use the correct method to solve the problem quickly, accurately and economically.
second, separation method
this method is a component (such as a), which controls or protects several other working components (such as b, c and d). When one of the work pieces (such as B) fails, it will affect the control piece (A) and cause other work pieces (C or D) to fail to work normally. When the control part (a) breaks down, we don't know which of the work parts (b, c, d) breaks down. Let one of the work pieces (b) not work first. If the control piece (a) works normally with other work pieces (c, d), it means that the work piece (b) is damaged.
Example: A Mercedes-Benz 32 car sometimes has no air conditioning, the fan doesn't work, and the No.21 insurance is often burned.
It is known from the insurance instructions that the insurance controls the power cord of the speed regulating resistor of the fan, controls the wiper and provides one of the power cords of the air conditioner. So first remove the plug of the fan speed regulating resistor, or burn the safety; Unplug the automatic air conditioner computer and still burn the insurance; So we unplugged the wiper plug, because the power cord mainly provides the fire wire for the wiper nozzle sensor. When unplugging the plug, we found that the wire harness showed signs of looseness between the hood bracket and the nozzle. When the hood was closed, the harness was pinched by the engine bracket and grounded. After correct handling, the fault is solved.
this method is also applied to the repair of automatic transmission, when one or two gears have problems. We can find out the problem by testing the oil pressure and stall point of each gear before disassembling the automatic transmission, and then comparing the direction of the oil circuit.
in addition, according to the unified regulations of international automobile manufacturing, CAN-BUS system will be adopted in vehicles after 2. Using the separation method will be of great help to help us deal with future vehicle failures < P > Third, step by step < P > This method is to use what we have learned and various testing equipment to find faults step by step. This method is often used for some soft faults and intractable diseases.
example: a Mitsubishi V6 car, with the throttle up to 3r/min. We first check the ignition system, replace the spark plug, and measure the high-voltage line, which meets the standard value. Clean the gasoline filter and test that the oil pressure of the oil pump is normal. Cleaned the fuel injector. Clean the throttle intake manifold space agency to ensure the normal intake system. But the problem has never been solved. The engine fault code was retrieved by testing instrument, but there was no fault code output. The main sensors were detected by oscilloscope, which met the standard value. Explain that the circuit system is normal. Check the ignition timing and cylinder pressure, which are normal. Among several major systems, only the exhaust system has not been checked. So the muffler was disassembled, resulting in smooth refueling and the failure phenomenon disappeared.
The exhaust pressure of the muffler is often neglected. In the vehicle with electronic fuel injection system, the muffler is equipped with a three-way catalyst. After a long time, there will be blockage, resulting in too high exhaust pressure, leading to poor engine refueling, high temperature and other faults. This kind of fault often occurs in Mercedes-Benz, BMW, Daewoo and Hyundai.
fourth, the inverse method
this method is to combine all the fault phenomena, think calmly and analyze the causes of these faults before dealing with them. That is, from the reason of the phenomenon, find out the key to the problem and focus on the breakthrough.
v. comparison method
This method is to solve the fault by exchanging components or comparing values of two identical vehicles. This method is suitable for special maintenance stations and dealing with difficult problems. Although this method is unscientific, it can solve the fault in time and accurately, and receive economic benefits in time.
Wrong ways to maintain the car 1. Waxing in a circle-poor effect
Many people habitually wax the car body in a circle, which is an incorrect method.
the correct waxing method is to do it in a straight line, alternately horizontally and vertically, and then make the last beating in the direction of rain flow, so as to reduce the concentric rings on the surface of car paint.
2. Too much oil-easy to break down
When the oil in the oil pan of the engine is insufficient, the friction between the bearing and the journal will aggravate the wear degree due to the small amount of oil, and even lead to a bearing burning accident.
However, if there is too much engine oil, the crankshaft handle and the big end of the connecting rod will be violently stirred when the engine is working, which not only increases the internal power loss of the engine, but also increases the amount of engine oil splashed on the cylinder wall, resulting in engine oil burning and discharging failure. Therefore, the oil in the engine oil pan should be controlled between the upper and lower scribed lines of the oil dipstick.
3. Too tight bolts-permanent deformation
There are many fasteners connected by bolts and nuts in automobiles, so it should be ensured that they have sufficient pre-tightening force, but they should not be tightened too tightly, on the one hand, the connectors will be permanently deformed under the action of external forces; On the other hand, the bolt will be permanently deformed by tension, and the pre-tightening force will decrease, even causing slipping or breaking.
4. The fan belt is too tight-bearing load is high
In summer, the temperature is too high, and some drivers will increase the tightness of the fan belt, which will cause the fan belt to be too tight, but I don't know that this is wrong.
the fan belt should be kept tight, because too tight will lead to excessive bearing load, increased wear and power consumption, and at the same time, it will bend the pump shaft, lengthen and deform the belt, and shorten its service life.
5, the new battery does not charge-shorten the life
The first charge of the battery is called the first charge, which has a great impact on the service life of the battery. If you don't charge, add it? Water? Direct use, the battery capacity is not high, the life will be shortened; If directly charged, it will also shorten the life. Usually, the initial charging of the battery is after the electrolyte is filled, and it can be installed and used by charging with a small current for about 1 hour.
6. The equipment in the car is added at will, which will affect the driving safety.
Some car owners add all kinds of equipment in the car themselves. If this modification is not handled properly, it will often bring adverse effects on the performance of the car, the convenience and reliability of handling, and it is easy to leave sequelae or affect the driving safety.
7. The cooling water temperature is too low-the engine is worn
It is hot in summer, and some drivers blindly require the cooling water temperature to be as low as possible in order to prevent the engine temperature from being too high; Some drivers simply remove the thermostat in order to achieve the purpose of cooling down. These practices are wrong.
tips for car maintenance 1. when checking the tire pressure, also check the tire wear
difficulty index: ★☆☆☆☆
it is the most important thing you can do in maintenance to ensure that the tires are in good condition. The road traffic law suggests that car owners check the tire pressure once a week, and it would be better to check the tire wear by the way at this time.
when checking the tire pressure, first find the tire standard pressure chart, which is usually located in the door, the fuel tank cover or the vehicle owner's manual, indicating the standard range of tire pressure and used to judge whether people are overloaded.
Because of thermal expansion and contraction, you need to cool the tire to make the measurement more accurate. Remove the dust cover on the tire valve, press the valve interface of the tire pressure gauge against the tire valve, and detect the tire pressure; You can also use the manometer on the tire pedal pump or on the air pipe of the gas station. If the manometer shows that the tire pressure is too low, it is necessary to fill the tire with an air pump to a reasonable value.
when you measure the value, you can also check the tire grooves and tread scratches. If nails are found on the tread, don't pull them out, because it may cause discouragement. At this time, it is necessary to slow down the speed, find a tire repairer or go to a dealer, and repair some damage at a low price, or replace it with a new tire.
finally, check the tread depth. You can use a tread depth measuring instrument, or you can use a one-dollar coin. The outer edge is about 1.85 mm thick, which is the recommended minimum depth of tread. Insert the coin into the tread pattern. If you can see the outer edge of the coin, you need a new tire. According to the road traffic law, The tread depth of the middle three-quarters of the whole tread needs to be at least 1.6 mm. ?
2. If you are a technical house, you can also do it yourself.
Difficulty index: ★★★☆☆
Although this maintenance difficulty rating is three stars, there are different models. Some cars may be finished in two minutes, some cars may take two hours, and some cars will wear their fingers. Compared with modern models, it is usually easier to maintain the old car headlights, because modern models are generally difficult to touch the inside of the headlights.
most headlight bulbs are secured by metal clips in the lampshade. Once the lampshade and base are removed, and then the clip is removed, the light bulb can slide out. Take off the light bulb and then slide the new one in, being careful not to touch the glass. Connect the base, put back the metal clip and lampshade, and you can try the new lamp.
taillights are generally easier to maintain because they are easier to disassemble and assemble. Before opening the bulb bracket, you need to open the interior decorative panel of the car trunk. In most cases, a bracket supports multiple light bulbs. Most taillight bulbs use snap-on devices, so you need to gently press the bulb and rotate it, which is a bit like a child-resistant medicine bottle. Then press the light bulb in the reverse order.
3. The windshield washer fluid is properly added by itself.
Difficulty index: ★☆☆☆☆
This maintenance is too simple. First of all, find the windshield washer tank, which is generally located under the front hood and marked with a washer nozzle. Generally, the lid of the can is snap-in. If you find a spiral, you have the wrong one. Please check the manual for confirmation.
after opening the cover, fill the funnel with washing liquid. Special cleaning solution is better than ordinary water and mixed liquid of water and cleaning solution, because it has good anti-freezing and cleaning effect. Fill the liquid storage tank and cover it.
4. Don't be careless about antifreeze
Difficulty index: ★★★☆☆
The function of antifreeze is to prevent the engine water tank from freezing. It is also called coolant, because it can take away the excess heat energy generated by the engine during operation, so that the engine can run at normal working temperature, and you can avoid being trapped in the vast steam on the roadside. Therefore, don't just use water as antifreeze.
the coolant storage tank is located under the hood, and there is an identifiable warning sticker on the tank cover. But it's best to check the manual to make sure it's correct. Before opening the cover, please make sure that the engine is in a cooling state, so as to avoid rapid heating and rapid ejection of the frozen liquid.
The anti-boiling and anti-freezing performance of antifreeze is not permanent, so it needs to be replaced every few years. Coolant testers in parts stores can help you measure relevant data to decide whether it is necessary to replace it.
There are many kinds of antifreeze to choose from, so it's best to buy the right product according to the manual and the seller's advice. But no matter which product you choose, you need to add the right water according to the coldest weather. Everyone should make a decision according to the manual and professional advice. Finally, open the liquid storage tank and fill it with liquid. It is best to use a funnel to prevent the liquid from leaking and damaging the car paint.
5. It is not difficult to check the oil
Difficulty index: ★☆☆☆☆
It is also easy to check the oil, but for accurate measurement, it is also necessary to ensure that the engine is in a cool state and park the car on a flat place. After determining the position, insert the engine with a dipstick (the handle is usually yellow or orange).
Pull out the dipstick and dry it with a roll of paper. Be careful not to drip oil. Repeat the operation again and then take it out again. At this time, the oil stops somewhere between the minimum and maximum values. If it is at or near the maximum, everything is fine.
6. Make up the oil at any time
Difficulty index: ★★☆☆☆
If the dipstick shows that your oil is near the minimum value, you have to add some oil. In order to avoid engine damage and warranty failure, you have to choose the correct grade of oil. This is written in the manual, and the dealer will also tell you the relevant information.
oil labels are usually expressed in the form of numbers and letters, such as 1W-3, but also in synthetic engine oil and non-synthetic engine oil. When the engine is cold, find the oil cap (the top of the engine is marked with the oil pot). It is best to clean up the dust and debris around before opening the cover to avoid falling into the engine.
after opening the cover, use a funnel to slowly pour the oil into the engine. Wait a moment and then measure the depth with a dipstick. The value should be less than the maximum value. Add more if necessary, but don't fill it too full. Take out the dipstick and cover it, and wipe off the dripping oil.
7. The air filter should also be cleaned and maintained.
Difficulty index: ★★☆☆☆
The air filter plays a great role in filtering out dust and sundries in the air and protecting the engine, so its cleaning and maintenance is also very important. Most of the filters are located in the plastic box on one side of the engine. To open the top of the bellows, you need to undo some metal clips or screws. Air filters are usually yellow with orange edges. Take out the filter and put in a new filter after writing down the placement direction. Finally, cover it and install the metal clip.
8. Spark plugs are not uncommon.
Difficulty coefficient: ★★★★★☆
The importance of spark plugs is self-evident. The spark it produces can ignite the fuel in the engine, so it must be maintained well. However, because it ignites sparks in the engine, it will produce black deposits in the long run, so it needs to be replaced every few years.
Spark plugs are different, so you should consult the seller or parts store before buying. Its replacement varies from car to car, but no matter what kind of system your car is, you should ensure that the engine is in a cool state before replacement, and only change one spark plug at a time.
many modern cars use ignition coils wrapped in plastic and attached to the top of the engine. We can remove the fastening bolt with a socket wrench, then untie the wire harness and gently take down the coil. In the structure of old cars, each spark plug has a ignition wire (also called HT ignition wire), which needs to be removed every time.
finally, carefully unscrew it from the engine with a spark plug extractor. If you can't rotate, don't use force to avoid damaging the engine. At this time, you should seek professional help. Remove the old spark plug, apply a little copper oil on the thread of the new spark plug and screw it in place. Similarly.