Case Analysis And Explanation

1. Check the recommended engine oil viscosity on your maintenance manual
If 5w30 engine oil is used for the original vehicle, the fuel consumption increase is normal after 10w40 is replaced!
The increased viscosity of engine oil increases the frictional resistance and also deteriorates the low-temperature fluidity. Not only does fuel consumption increase, but it also increases engine cold start wear!

2. Check if the engine oil is over-filled. If the engine oil is above the upper limit of engine oil level gauge, the oil seal pressure will be also increased to cause oil leakage.

3. After the vehicle maintenance, the change of engine oil and engine oil filter, etc. will not increase the engine noise. These faults are often caused by inappropriate re-installation of some parts during maintenance. For example, the air filter screws are not tightened when the air filter is changed during maintenance, or the buckle of air filter is not tightened appropriately to cause the air leakage at the filter. In this case, we may hear the engine air suction sound during acceleration. You need to check if it is caused by inappropriate installation of air filter.

4. Why does the fuel consumption of vehicle originally with low fuel consumption suddenly soar? When you find the fuel consumption of your vehicle gradually rises during driving, your vehicle may not have a serious problem, but some accessories of your vehicle need to be maintained or replaced as the mileage increases.

NO.1: No maintenance of engine—fuel consumption increased by 10%
The fuel consumption will normally increase by 10% or 20% for a poorly maintained engine, and a too dirty air filter can also result in the increase of fuel consumption by 10%.
The abnormal ignition system of the engine also has a great influence on the fuel consumption. For example, inaccurate ignition time, high-voltage wire electric leakage and spark plug carbon deposition to cause weak ignition all will reduce the engine combustion efficiency and increase the fuel consumption.

NO.2: low gear and high speed—fuel consumption increased by 10%
If the vehicle travels at a high speed in the gear 3 position for a long distance, the fuel consumption will be increased by 10% compared with the normal travelling at grade 4. If the vehicle travels at gear 2 in replace, the fuel consumption will be increased further.
Any type of vehicle has its economic speed at which the fuel consumption is the lowest during traveling. The fuel consumption will rise in case of lower than or higher than such speed, and will greatly increase after exceeding certain speed.
For example, the fuel consumption of Buick GS car is 6.47 liters per 100 km at the speed of 70 km/h; it rises to 9.46 liters per 100 km at the speed of 120 km/h; it will greatly increase if the speed reaches 200 km/h.

NO.3: Insufficient tire pressure- fuel consumption increased by 1%
Maintaining a normal tire pressure level is also a good way to reduce the fuel consumption. If the tire pressure is insufficient, the rolling resistance will increase greatly. According to the test, the fuel consumption will be increased by 1% when the tire pressure is 2 psi lower than the specified value (pressure unit: pound per square foot). Excessive tire misalignment or excessive wear may also increase fuel consumption.
Always pay attention to the state of the tires and maintain the tire pressure, which not only saves fuel but also increases the service life. If the brake is seized, you can carry out a slow-speed neutral sliding test to ensure that the brake does not have such state.

NO.4: Bad driving habit-- fuel consumption increased by 2-3 times
The incorrect driving habit has the greatest impact on the fuel consumption. During driving, especially in case of unsmooth traffic, red light and lane change, the problems such as rapid acceleration and sudden braking are very common.
Experts have carried out the accelerated fuel consumption test. After the vehicle traveled to the test road section at a constant speed, the vehicle tester stepped on the accelerator to the end to finish driving on the specified distance. The result indicates that the fuel consumption is increased by 2 to 3 times compared with the uniform speed. When the vehicle travels in a low gear position for a long time, the fuel consumption will be inevitably increased.

NO.5: Excessive carbon deposit—soared fuel consumption
The excessive carbon deposit is mainly caused by the use of poor-quality engine oil, and the coke-like substances generated by unsaturated hydrocarbons and colloidal impurities at high temperature will roughen the intake pipe wall to affect the intake effect and the quality of the mixed gas, so that the fuel consumption rises sharply.
Thus, the carbon deposit shall be cleaned once half a year.

NO.6: Old battery
You may not know that the battery is a gas guzzler. In fact, the relationship between the electric circuit and the oil circuit is far beyond your imagination. When the battery service time reaches 2-3 years, it will cause loss of electricity, which will result in insufficient starting voltage. The motor will drive the engine to be weak. The spark plug will not jump out of the strong and powerful spark, so that the ignition energy will be low and the fuel consumption will soar.

NO.7: Vehicle overload—vehicle damage, fuel consumption
Some car owners regard the trunk as a warehouse. Everything, useful or not, is stuffed in the trunk, which increases the self-weight of the car. However, the vehicle weight is in direct proportion to the fuel consumption. The fuel consumption will be reduced by several percentages whenever the vehicle weight is reduced by 10%. Therefore, reduce the burden of your car in order to save the fuel consumption.

NO8.: Fuel
In summary, to reduce the fuel consumption of the car, in addition to routine inspection and maintenance, good driving habit is the key.
In addition to the above-mentioned common causes, winter factors, car start in winter, full opening of air gate, large fuel injection and thick oil will also cause high fuel consumption. If you only check the fuel consumption displayed on the ECU and do not drive for a long distance, the fuel consumption will rise normally.
Generally, the engine oil and engine filter are changed together. The standard change cycle depends on the vehicle model. Generally, they are changed once per 5000 km or per year, whichever is earlier.

5. Now some car owners find a problem. After the maintenance at the 4S shop, the noise of their cars gets bigger and the fuel consumption is increased. Many car owners want to know the reasons.
According to the conventional thinking, after the car is maintained, the working condition of the vehicle will be improved, its performance will be enhanced and the mixed gas in the engine will be combusted better. The fuel consumption and noise shall be effectively reduced. Why are the fuel consumption and noise increased on the contrary after maintenance?
In fact, in the current automobile industry, this phenomenon is still relatively common. There are many reasons, some of which are normal, and others need to be noticed during maintenance. We simply analyze this phenomenon below:
1). Does the car owner drive his/her car in a place with particularly poor road conditions soon after the maintenance? If so, it is normal for the fuel consumption to increase.
2). Environmental factors can sometimes cause such problem. For example, is the maintenance made in summer or winter? After the air conditioner is switched on in summer or winter, the fuel consumption will increase. If the air conditioner is not switched on in winter, the opened windows will also increase the fuel consumption. The ventilation and cooling by opening windows will lead to an increase in the driving resistance of the vehicle. Especially when the vehicle is traveling at a high speed, the driving resistance will seriously affect the fuel consumption of the vehicle.
These factors are normal phenomena. As long as the car owners always pay attention to these problems during the daily driving, the problems of fuel consumption and noise can be greatly improved.

There are some other problems to be noticed during vehicle maintenance:
1). Is the throttle valve cleaned during vehicle maintenance? If so, the accumulated carbon deposits at the throttle valve will be cleaned, the opening of throttle valve will be increased and the corresponding oil injection amount will also increase. So, the fuel consumption will increase correspondingly. Therefore, during the vehicle maintenance, the program matching shall be re-made by the computer for the throttle valve after cleaning on the one hand; the throttle valve needs to be self-adjusted in some time. In this period, the fuel consumption and noise will increase. However, you don’t need to worry about that, for it is only temporary.
2). If the engine is filled with too much oil during the vehicle maintenance, the fuel consumption will also increase. Excessive engine oil volume will increase the running load of engine, and part of power generated by the engine will be lost accordingly, indirectly causing insufficient engine power output and increased fuel consumption. Attention shall be paid to the details during the vehicle maintenance. Add appropriate engine oil to the engine according to the relevant markings.
3). If tires are replaced during vehicle maintenance, incorrect size of new tires replaced or insufficient tire pressure due to some reason will increase the oil consumption and noise. The car owners shall pay attention to it.
4). Spark plug problem; if the spark plug is replaced, it is necessary to note whether the spark plug quality and model meet the original vehicle requirements. If the spark plug is not replaced, it is necessary to check whether the spark plug electrode gap meets the requirements. If the spark plug gap does not meet the requirements or is damaged, the ignition quality will be degraded, the mixed gas will be combusted insufficiently, the noise will increase, the power will be insufficient, and the fuel consumption will increase.
Friendly reminder: Low temperature, tire slipping due to rain and snow and low friction all may cause certain fuel consumption.