urhunden
Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
  
|
| info screen fuel consumption |
|
I have a TDV6 auto. On the info screen I get a figure for fuel consumption, but looking at trip meter and actual fuel from the gas pump, gives a different figure.
In fact the difference is 12.6 litres/ 100 kms at the info screen and 14.5 litres/100 kms actual figure.
Is there a way to adjust the computer in the car to get a better figure.
|
 25th Mar 2010 3:17 pm |
|
|
al cope
Member Since: 08 Nov 2005
Location: Oldbury, WM
Posts: 10297
|
in a word - no. some are OK, most seem to be rubbish. My old one wasnt too bad, latest one is hopeless. Ignore it, its only distracting you from the joys of having a D3 anyway 
Al Volvo XC90 B5 Plus Dark
Gone - MY18 D5 HSE - Corris on 22's with Black Pack
Now gone - MY16 D4 SE Tech, Loire Blue, Almond Leather, Privacy, plus some other goodies.
Old - MY12 D4 SDV6 XS Auto - Ipanema Sand with Almond Leather - Plus other niceties, and D4.com sticker
Older - D3 TDV6 XS Auto - Lugano Teal with Almond Leather, 20" Stormers, Shiny Tailpipes, DVD/TV - and obligatory D3 sticker
Ancient - D3 TDV6 S - Tonga with Ebony, 20" Stormers, satnav & DVD
|
| 25th Mar 2010 4:16 pm |
|
|
wvlenthe
Member Since: 07 Jan 2009
Location: Arnhem
Posts: 1967
  
|
| Re: info screen fuel consumption |
|
urhunden wrote:Is there a way to adjust the computer in the car to get a better figure.
Changing tyre size would be the only option. But that will give other problems.
Glad my trip computer is dead on!
regards,
Wiljo D3 V8 HSE Auto in Zermatt silver - driveway version gone but not forgotten, only the living room cupboard version remains
|
| 25th Mar 2010 8:46 pm |
|
|
DaveS
Member Since: 15 Aug 2009
Location: Weybridge
Posts: 241
 
|
Does anyone know whether fuel used by the Fuel Burning Heater is included in the MPG calculated by the computer? If not, this could account for the difference between the computer and driver's calculations, especially in colder climates such as Sweden.
|
| 25th Mar 2010 11:16 pm |
|
|
urhunden
Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
|
good thinking, but would the burner take that much fuel?
|
| 26th Mar 2010 12:30 am |
|
|
ronald.soak
Member Since: 29 Apr 2008
Location: London
Posts: 516
|
I understand that the FBH is rated at 5kw which would probably equate to 0.5 litres / hour so at 80kmph the fuel consumption would increase by 0.625 litres/100km. The efficiency of the FBH might be low. but, even in Sweden, I would be suprised if the FBH ran continuously unless all journeys were short.
|
| 26th Mar 2010 1:18 am |
|
|
Navigator
Member Since: 17 Mar 2010
Location: Stay at Home. One of the lives you save could be your own.
Posts: 5104
 
|
Even if the trip computer's figures are wrong it can still be very useful.
You can still use it to minimise fuel use - it is just the NUMBER that will be different from the real value. The minimum will still occur with the same driving/speed combination as shown on the screen. A vaccine does not stop you catching a virus, or passing it on, or getting ill from it, really ill. It does reduce the likelyhood of you dying when really, really ill. Stay Alive - KEEP AWAY FROM PEOPLE.
|
| 26th Mar 2010 1:22 am |
|
|
discoBizz
Member Since: 20 Sep 2008
Location: Manchester
Posts: 1416
|
If it helps, the deviation on average on my car is 2.8 lt/100km (after 50 or so tankfuls of measuring), so knowing that I mentally adjust when I can be asked... though with VAT at 21% and extra fuel duties where I currently live, fuel consumption does become an issue 
I can't see how the car's meter would adjust for the FBH, as far as I can tell it's throttle position+speed+tank fuel level that it's using  (not checked this, just empirical evidence)
|
| 26th Mar 2010 10:58 am |
|
|
Bob.
Member Since: 05 Apr 2009
Location: 52�N 2�W
Posts: 94
|
I think the average fuel consumption may be calculated in a similar way to the FL2. so would include the FBH.
"The instrument cluster receives 2 fuel tank level readings and calculates an average value of the amount of usable fuel in the tank from the 2 signals. Every 200 meters of vehicle travel the instrument cluster re-calculates this value to determine how much fuel has been used. This value is then averaged over the last 31 miles (50 kilometers) of travel and displayed in the trip computer. The distance traveled signal originates in the ABS module."
|
| 26th Mar 2010 11:17 am |
|
|
discoBizz
Member Since: 20 Sep 2008
Location: Manchester
Posts: 1416
|
Bob, then yes, whatever the FBH uses is implicitly included in the calculation (though in my case the FBH has only fired once or twice - pretty warm down by the med 8) )
|
| 26th Mar 2010 11:26 am |
|
|
TallPaul
Member Since: 03 Jan 2008
Location: Near Reading
Posts: 1214
|
Its been programmed with optimistic calculation, over several thousand miles and litres, its consistently 2 MPG optimistic.
I guess they just hope you look at the readout, don't feel bad about the poor consumption, and hope you never work it out yourself?!
|
| 26th Mar 2010 11:35 am |
|
|
discoBizz
Member Since: 20 Sep 2008
Location: Manchester
Posts: 1416
|
 until eventually you become your usual petrol station's "customer of the month" at which point you've got to wonder  
|
| 26th Mar 2010 11:42 am |
|
|
DaveS
Member Since: 15 Aug 2009
Location: Weybridge
Posts: 241
|
I find it hard to believe that the MPG could be calculated by readings from the fuel guage sender and give anything like a real time reading. I had assumed that it would use information from the electronic fuel injection system. This was why I thought that it might ignore the FBH although it could monitor the number of times that the FBH fuel pump operated.
|
| 26th Mar 2010 9:33 pm |
|
|
chrisc
Member Since: 18 Oct 2009
Location: Staffordshire
Posts: 362
|
my father in law says the best way to find out the mpg is to fill the tank to the top run it till its nearly empty then fill it again,check how many litres you have had to put in,then you can find out how many litres its used,then compare the miles that youve done,that said i cant afford to fill my d3 to the top and im not that bothered any more about economy i try and skip the mpg display whenever i can now
|
| 26th Mar 2010 9:41 pm |
|
|
urhunden
Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
|
Dear Chrisc,
this is how I get my "real" consumption.
Unfortunately the car computes in a different way that get a wrong result.
|
| 26th Mar 2010 9:59 pm |
|
|
