- May 29, 2013
- 2,631
- 19,526
- Funster No
- 26,231
- MH
- Chausson best of Flash 10
- Exp
- Several years now
In the above vehicle would anyone know how the average fuel results are arrived at ?
It would seem to be a pretty simple calculation, count the number of injection pulses and measure distance travelled, a bit of maths and there you have your average fuel. And it should be pretty accurate. But is it ?
So, it is easy to count the injection pulses, but what provides the distance input ? I'm guessing some form of toothed cog sensor on a road wheel, anybody confirm that ?
Then we come to the calculation itself. I read a snippet somewhere that says the average fuel is calculated from the last press of the reset button as a continuous calculation. Like if you pressed reset on the day you bought it then 10 years later it would be showing you the average fuel consumed over those 10 years.
So why am I asking I hear you ask. Well, when I first got the MH brand new, on a Ford 2.2 140ps engine, weight 3t, it always showed an average fuel of 26.9 mpg. sometimes dipped a little under, but never above that. I thought that when the engine had done 10,000 miles I would see the average fuel increase. Nope, stayed the same.
But lately the reading has been all over the place. Bearing in mind I normally do 62mph on the motorways, the following is referring to motorway travel only. So sometimes the average shows 22.4mpg. I press the reset button and it will again show that reading over say 20 miles. I press reset again and the reading might show 24.7 mpg over the next 50 miles. Press again and it might show 26.9 for the next 50 miles. So I am wondering what might be affecting the average mileage so dramatically, bearing in mind I am doing the same speed on normal motorways, having the same weight and in the same weather conditions.
It would seem to be a pretty simple calculation, count the number of injection pulses and measure distance travelled, a bit of maths and there you have your average fuel. And it should be pretty accurate. But is it ?
So, it is easy to count the injection pulses, but what provides the distance input ? I'm guessing some form of toothed cog sensor on a road wheel, anybody confirm that ?
Then we come to the calculation itself. I read a snippet somewhere that says the average fuel is calculated from the last press of the reset button as a continuous calculation. Like if you pressed reset on the day you bought it then 10 years later it would be showing you the average fuel consumed over those 10 years.
So why am I asking I hear you ask. Well, when I first got the MH brand new, on a Ford 2.2 140ps engine, weight 3t, it always showed an average fuel of 26.9 mpg. sometimes dipped a little under, but never above that. I thought that when the engine had done 10,000 miles I would see the average fuel increase. Nope, stayed the same.
But lately the reading has been all over the place. Bearing in mind I normally do 62mph on the motorways, the following is referring to motorway travel only. So sometimes the average shows 22.4mpg. I press the reset button and it will again show that reading over say 20 miles. I press reset again and the reading might show 24.7 mpg over the next 50 miles. Press again and it might show 26.9 for the next 50 miles. So I am wondering what might be affecting the average mileage so dramatically, bearing in mind I am doing the same speed on normal motorways, having the same weight and in the same weather conditions.