Oxygen sensor oxygen sensor a mileage of about 116 thousand km, equipped with 16V engine, automatic transmission of Dongfeng Citroen Sega 1.6 three sedan. Users reflect: the fuel consumption of this vehicle is obviously higher than before. Fault diagnosis: high fuel consumption is a difficult problem to deal with. First, it is necessary to confirm whether the fuel consumption is too high by road test. If the vehicle fuel consumption is proved too high, it can find the cause from the vehicle performance, vehicle status, driving habits and so on. Finally, the improvement method is determined according to the specific original cause, so as to solve the fuel consumption. The problem is too high. First, make a road test on the user's high fuel consumption problem, let the user drive the vehicle to a nearby Sinopec gas station to fill the tank with oil (a gas gun), and then let the user drive a long distance (without air conditioning in the process) in the area he often drives in accordance with his usual driving habits, and press the combined instrument at the same time. The daily mileage button on the board is used to record the mileage. After driving the 200km, then the same gas gun is used for refueling at the gas station just after the filling, and the amount of injection is recorded after the filling of the gun. The value of the 100 kilometer fuel consumption is 10.2L/100km, and the normal condition is integrated. The fuel consumption should be 7.6L/100km, and the fuel consumption in suburb should be 5.8L/100km. Although the actual working conditions of the vehicle are not the same as the comprehensive working conditions and the suburban conditions, there is no comparability. However, according to the experience, the oil consumption is more common in 9 ~ 9.5L/ 100km because of the frequent traffic jam, the traffic light and the engine speed, and the oil consumption is more common, and the oil of this user is more common. The consumption is somewhat higher. Air pressure check on four tires (if the tire gas is too low, it will increase the resistance of the vehicle running, and eventually lead to high fuel consumption). It is found that the pressure is a little lower than the normal standard value, so the air pressure is adjusted to the standard value with the pump, and the model of the four tires is compared with the reference vehicle. There are problems (displacement, model, and load are the same, if the A car uses the original type of tire, and the B uses a larger tire, then the B is more resistant to fuel than the A car). As far as possible to reduce the load of the vehicle, each increase of the vehicle weight, the fuel consumption will rise accordingly, allowing the user to remove unnecessary ornaments and articles from the car, such as the spare parts of the trunk. Check the user's maintenance records to determine whether the user's engine oil is marked according to the specified label, and the inspection result shows that it meets the requirements. The viscosity of oil is the main index of oil performance, such as 10W-30, in which W indicates winter, the number of its front is smaller, the thinner viscosity of the oil is thinner and fluidity, the lower the environment temperature can be used, the better the protection ability of the engine at the cold start; the number of W after the oil is the index of the high temperature resistance of the oil. The higher the flow of high temperature, the better the protection performance of the engine oil at high temperature. The excessive selection of the high Bob oil will increase the working resistance of the engine components, both power consumption and fuel consumption. Every user's maintenance is carried out on time at Dongfeng Citroen's designated outlets, and all the replacement brands are designated brands and models. Communicate with users and understand their driving habits and styles. It is best not to overtake frequently to reduce oil consumption at a constant speed. At the same time, we should master the distance between the car and the car and reduce the unnecessary braking. The good driving habits can reduce the oil consumption as much as possible. The Dongfeng Citroen Sega 1.6L is equipped with a high speed engine (TU5JP4 engine), whose minimum fuel consumption speed is around 2500r/min, allowing users to run as much as possible at this speed in normal time. If the speed is longer than this or below this, the fuel consumption may be increased. The state of the spark plug and the ignition coil is checked (if the bad work of the spark plug or the ignition coil system may cause the engine to burn badly, the fuel consumption is too high), the spark plug of the four cylinders is dismantled and replaced, and the operating wave form of the ignition coil is read and operated. The work waveform is compared with the normal waveform, and no anomaly is found. After the operation of the above steps, the effect of spark plug and ignition coil on fuel consumption can be reduced. The deposition of engine carbon is the deposit produced by the combustion of fuel and lubricating oil after incomplete combustion. First, the car itself contains colloid, impurities, or dust and impurities brought in in the process of storage and transportation, and accumulating mud like sediments in the car oil tank and the oil pipe. Secondly, the volatile components such as olefins in gasoline are oxidized and polymerized at a certain temperature to form colloid and resin like sticky substances. These sticky deposits will become hard carbon deposits in the nozzle, intake valve, combustion chamber (cylinder head and piston top). In addition, due to urban traffic congestion, cars are often at low speed and idle state, which will aggravate the formation and accumulation of these sediments. The carbon deposition in the throttle body is cleaned by special cleaning agent, the carbon deposition of the engine cylinder block is disintegrated, and then the engine is run. After the related inspection, the user can operate according to the above requirements when the vehicle runs. The fuel consumption of the vehicle is reduced obviously when the user is converted. It is basically maintained at about 9L/100km to meet the requirements of the user. Maintenance summary: we believe that the fuel consumption of users is too high for the following reasons: (1) users' use and driving habits. When running the vehicle, attention should be paid to the control of engine speed, minimizing the number of pedal on the brake pedal and reducing the number of acceleration. The state of the vehicle. The vehicle load should be reduced as much as possible, and the tire pressure should be kept at a standard value. 3. The working state of the engine's carbon deposit, spark plug and ignition coil. All the above reasons will more or less affect the fuel consumption of the vehicle, and all the factors superimposed together will have about 10% of the oil consumption changes, so the problem of determining the high fuel consumption of the existing vehicles should be taken in a multi - pronged strategy to produce immediate effect. Comment: from the diagnosis and exclusion process of Shijia fuel consumption too high, we can see that the author still knows the three points, but the rules are missing. Because of the high fuel consumption of EFI vehicles, there are generally three, one is vehicle condition, two is road condition, and three is driving technology. The vehicle performance and vehicle condition described in the article are actually the same problem. Among them, fill the filling station with petrol, test the car back, the same gas station, the same refueling gun, fill the test method is correct. On the test road, the best way to choose the highway, because in the expressway on the same speed, usually do not have driving technology problems, there is no road conditions, in such an environment side test 100km, oil consumption is normal, generally shows that car conditions have no problem. The reason for the high fuel consumption is not the road condition or the driving technology problem. If the test is a problem of car conditions, there are some trouble, because in practice, there are dozens of reasons may cause excessive fuel consumption, but we must grasp the main contradiction. In order to quickly diagnose the cause of high oil consumption, the key point is to carry out the condition of the fault code detection side and the data flow analysis of the electronic control system, and can also carry out the oscilloscope analysis and the endoscope examination. Without conditions, it can be tested from three aspects that affect engine performance. The first is the compression ratio, the two is the mixing ratio, and the three is the ignition timing. If the author starts with compression ratio check side, it may be found that it is increased due to too much Coke in the combustion chamber and smaller volume. If the mixing ratio is detected, the range of voltage change will reach the limit of the two ends, that is, the change between 0.1 and 0.9V will be found to be the fault of the high oil consumption caused by the carbon accumulation. Because new cars and carbon vehicles are very few, voltage signals usually change between 0.3 and 0.7V, and a little more Coke will change between 0.2 and 0.8V. The heavier carbon deposits will change between 0.1 and 0.9V. If the ignition timing is detected, it may also be found that ignition is early or even detonation, which will cause high fuel consumption. Once the diagnosis of carbon accumulation is the main cause of high oil consumption, it is possible to remove the carbon or only remove the cylinder cover, and to remove the coke on the combustor and the intake gate pole, and to grind the valve to restore the normal fuel consumption. It is not necessary to disassemble the engine assembly to remove carbon deposition, which will increase the maintenance cost. It is necessary to know that as long as there is no fault in the oil burning, the high oil consumption failure caused by mechanical causes is simply removed, as long as the cylinder cover is dismantled, the cylinder cover is cleaned and cleaned to eliminate the hidden danger, and it will be effective.