M

mecho

New Member
Hi all,
I have RR P38 2,5 diesel 1998,and one small but iritating problem - on display, fuel scale is working perfect(showing exactly how much fuel is in the reservoir),kilometars to drive is allso showing real, but medium consumption allways show about 40% less than real(as a example, if there show that mediim comnsumption is 9,3 l/1per 100km, in reality it's 13 l/per 100km)! Can somebody tell me what is the problem,and how eventualy can I fix these false reading fuel consumption problem?Thanks in advance.
P.S.Sorry for my english. I'm from Macedonia,country with only wev P38.
 
Hmm, in the UK, the comsumption display is in MPG (miles per gallon), although I've never questioned mine, it was last reset over 1000 miles ago and currently shows average as 14.6 MPG (it is a 4.6!). The display is controlled by the BeCOM and I'm wondering if yours is set to metric units correctly rather than imperial, it's something that can only be done with proper diagnostic systems connected to your car.
 
Alan C said:
Hmm, in the UK, the comsumption display is in MPG (miles per gallon), although I've never questioned mine, it was last reset over 1000 miles ago and currently shows average as 14.6 MPG (it is a 4.6!). The display is controlled by the BeCOM and I'm wondering if yours is set to metric units correctly rather than imperial, it's something that can only be done with proper diagnostic systems connected to your car.
Click to expand...

I read the OP and thought something similar but couldn't get the numbers straight in my head, mind you it was rather late last night. The closest I got was something like miles per litre!
As already said I think you're going to need the car hooked up to a good diagnostic and see what's there.
 
Thanks for efforts buddie. On displpay all readings are "european"(my RR zas "born" in Italy),and fuell consumption is displaying l/100km. In the begeaning I only change language(italian>english), but, as you both sugest, maybe readinng miles per 100km maybe still stay i BCM. I'll inform you after diagnostic.... Thanks again.
 
The fuel consumption on the message display is at best 20%-25% accurate....whether that be km/l or mpg....

The best method is the brim to brim technique....

Brim the tank do a whole bunch of miles then brim the tank again....take note of the mileage/kilometres covered and the fuel quantity added....do some maths and that will give you the best reading.

I fill my tank every Monday lunch time and have a spreadsheet of figures, I currently average 26.45mpg....
 
Hi all good RR pals. Today I was in garage for diagnostic the problem - everything was fine with BCM and other setings. EU norms,english,consumption is in l/100km.... So, and I know that every car have false reading fuel consumption from 5(bmw) to 15%(Korean...), but when my RR display 7,1 l/100 km on autoban,and 9,3 l/100km urban it's like driving Fiat Seicento. Real consuption(wich I measure like you Saint) is 11 liters on autoban,and 13,5 in the town(allso normal considering 4wd,mass and so...).These paramatetars(11 and 13,5) was exactly readen in my previous P38,allso diesel.... Maiby some bad corenspodence betvean fuel tank,engine and display, or some problem with electronic "calculator" on display... If I,or somebody from these forum, find the solution lets post that. However,these is not comon and big problem. Best regards to all who want to help...
 
Dont trust the trip computer - mine got me all a tizzle when the consumption dropped off massively. I log the fuel consumption using my own maths, and it ranges from 24-36mpg on a DSE. The huge difference is the inaccuracy when filling up anything other than full. The Fuel gauge, as per owners manual, sometimes has problems displaying increase/decrease of fuel in the tank when its less than 15 litres. Therefore I can say my average is a healthy 30mpg (PSI fitted) not the 21MPG its telling me.

Wippersnappers and their computers and iboxes...
 
Silly question, do you always do a reset before monitoring the reading? If you only check it when cruising at a constants speed it will of course under-report. Best to reset it and drive normally for a couple of weeks. Then you a get a reasonable average. However note that this does skew significantly if you do a lot of idling at standstill or are in stop-go traffic a lot.

ps. about the only time i envy you diesel boys is every time i go to the pump. which is actually rather often. :p
 
Never bother mine now used it when I first bought car it was a novelty but it's a big v8 so it's a case of putting the stuff in cos I have to it'll never be economical
 
You must log in or register to reply here.

Similar threads

P
Range Rover P38 EKA and BeCM Lockout
Replies
6
Views
6K
Doolinjames
D
M
false display fuel consumption
Replies
0
Views
576
mecho
M