How to Diagnose your Vehicle if the Fuel Consumtion Increase? 2of 2


Customer Usage?
1. Warming up and running distance
A long period of warm-up will waste the fuel. When the engine is cold, more fuel is required and the idling speed is high due to fast idling. Based on these facts, when the running distance is short, the running time ratio when the engine is cold increases and the fuel consumption increases.
Warming up
To improve fuel consumption, reduce the warming up time as much as possible. Even in winter, stop warming up when the water temperature indicator begins to move (water temperature 40 to 50 degree centigrade).
2. Laden condition and the number of occupants
As the load and the number of occupants increase, the weight becomes heavier and fuel consumption increases.
3. Use of air conditioner
When turning the compressor of the air conditioner, engine power is used, increasing fuel consumption. The operation rate of the compressor increases as the temperature and moisture becomes higher. The amount of air blow decreases as the vehicle speed lowers, and the cooling performance of the condenser becomes worse. Accordingly, the load applied to the engine increases. Therefore, on a congested road when the temperature is high, fuel consumption increases by 20 to 30 %.
4. Electrical load
The load to the alternator increases as the quantity of electricity used increases, so fuel consumption increases.
5. Running in the city and on congested roads
Running under these conditions increases the fuel consumption, because the average vehicle speed is low, the amount of time the vehicle is stopped becomes longer, and frequent acceleration and deceleration is performed. On a intermittently congested road where there is frequent acceleration and deceleration, the fuel consumption will be greater than on a road where the vehicle speed is considerably low.
• Average vehicle speed Average vehicle speed can be simply calculated by distance and time. But when the vehicle runs long distance, there are congested roads and not congested roads during this running, so it is necessary to obtain each value by separating a certain block. In this case, it is necessary to clearly separate the ratio between the lows peed and high-speed running distances.
• Vehicle stoppage time When the vehicle stops, fuel is consumed, however, the running distance is 0 km, so the fuel efficiency becomes 0km/l. As the stoppage time becomes longer, fuel efficiency worsens
Customer Usage?
6. Running on the highway
On highways, When the vehicle runs at a constant speed, the fuel consumption often increases. But when the speed rises, the fuel consumption increases. Generally, decreasing a speed of 100 km/h to 80 km/h, the fuel consumption is reduced by 10 to 30 %.
7. Starting and accelerating
Fast start or sudden acceleration consumes more fuel than usual in order to reach the same distance or speed. Generally, a fast start or sudden acceleration consumes fuel equivalent to the amount consumed by running run approximately 100 m. To reduce fuel consumption, maintain a certain vehicle-to-vehicle distance and constant speed.
8. Wasting acceleration operation
Racing consumes fuel equivalent to the amount consumed by running approximately 50 m.
9. Shift operation
Generally, unless the driveability worsens, such as the occurrence of knocking, using a higher gear and making the engine speed lower will reduce the fuel consumption.
How is it Measured?
Many customers calculate fuel consumption by the full tank method. However, calculation by this method can lead to different results. Therefore, it is necessary to pay attention to the following points.
1. Fuel filling method and difference
When fuel is filled in the tank after running, the amount has to be equal to that before running. However, vehicle inclination, the person who fills, filling speed, etc. are not same, so the amount filled will be different. Accordingly, the calculated result for fuel consumption will be different.
How is it Measured?
2. Fuel filling timing and difference
When fuel is filled when only a small amount has been consumed, the running distance is also short. Therefore, the fuel consumption under this running condition can be calculated. On the other hand, when fuel is filled when the tank is almost empty, the running distance is long and the vehicle has been exposed to a variety of running patterns. Therefore, the fuel calculation result will be an average of the total results.
3. Important points to remember when measurement
To calculate the fuel consumption accurately, perform a road test based on the diagnostic questioning, with a fuel consumption meter and a hand-held tester attached and record data that shows the change in fuel consumption under different road conditions and driving methods.

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