Trip computer range error

Dorset Bob · 9th March 2012, 10:28

Yesterday when I pushed the stalk for the comupter it came up with a range of 990 miles (I wish it was true!). Having driven about 30 miles it is now showing 639 miles.
All the other readings like MPG, Average speed etc seem sensible and the fuel gauge looks to be working OK.
Anyone got any ideas? Thanks.

T-Cut · 9th March 2012, 10:53

I suspect it hasn't collected sufficient data to calculate a meaningful result. The system appears to compute from averages collected over a period of time. If the computer is reset, the calculations it provides are likely to be unrealistic. For the 'best' results, the computer should never be reset.

It also uses the calculated mpg data to predict the Range. If the current mpg figure is over-optimistic (which it usually is) then the range will be unrealistic. The mpg data should be calibrated by practical measurement (like a series of brim-to-brim tests) so the displayed mpg matches the actual mpg. There's detail on recalibrating the mpg data in the Diagnostic Mode HowTo.

TC

David3807 · 9th March 2012, 16:11

Quote:

Originally Posted by Dorset Bob

Yesterday when I pushed the stalk for the comupter it came up with a range of 990 miles (I wish it was true!). Having driven about 30 miles it is now showing 639 miles.
All the other readings like MPG, Average speed etc seem sensible and the fuel gauge looks to be working OK.
Anyone got any ideas? Thanks.

Commonish problem in cars around 2002. Glitch in instrument pack. Will gradually revert to proper figure as you have found. Adding some more fuel to the tank should also correct the figure - well it does with my 2002 tourer.

Adding more fuel forces the 'computer' to recalculate the range figure and it usually gets it right second time.

Dorset Bob · 12th March 2012, 19:33

Many thanks for your help on this one guys.
I will put some fuel in it and see what happens. I last reset the trip about 700 miles ago and it was working fine up until now. A glitch explains it, as I could not understand why the range is greater than the MPG x the maximum tank capacity in gallons.
The post by T-Cut in the "Diagnostic Mode HowTo" is brilliant and has revealed some interesting facts about my car (like it was built in June 2000 and registered on the 1st March 2001, just in time for the emissions road tax!).

I did not know so much information was held on the car and I am going to get one of those Bluetooth OBD2 devices so I can have a furthert look on my laptop.

Thanks again, a great site for help!

9th March 2012, 10:28	#1
Dorset Bob Senior Citizen Rover 75 2.5 Connoisseur SE,Chrysler 300C,124 Spider, Daytona 955i,Honda XL250 & Royal Enfield 650GT Join Date: Feb 2008 Location: The Kingdom of Wessex Posts: 6,976 Thanks: 2,391 Thanked 2,685 Times in 1,686 Posts	Trip computer range error Yesterday when I pushed the stalk for the comupter it came up with a range of 990 miles (I wish it was true!). Having driven about 30 miles it is now showing 639 miles. All the other readings like MPG, Average speed etc seem sensible and the fuel gauge looks to be working OK. Anyone got any ideas? Thanks.

12th March 2012, 19:33	#4
Dorset Bob Senior Citizen Rover 75 2.5 Connoisseur SE,Chrysler 300C,124 Spider, Daytona 955i,Honda XL250 & Royal Enfield 650GT Join Date: Feb 2008 Location: The Kingdom of Wessex Posts: 6,976 Thanks: 2,391 Thanked 2,685 Times in 1,686 Posts	A great help thanks Many thanks for your help on this one guys. I will put some fuel in it and see what happens. I last reset the trip about 700 miles ago and it was working fine up until now. A glitch explains it, as I could not understand why the range is greater than the MPG x the maximum tank capacity in gallons. The post by T-Cut in the "Diagnostic Mode HowTo" is brilliant and has revealed some interesting facts about my car (like it was built in June 2000 and registered on the 1st March 2001, just in time for the emissions road tax!). I did not know so much information was held on the car and I am going to get one of those Bluetooth OBD2 devices so I can have a furthert look on my laptop. Thanks again, a great site for help!

9th March 2012, 10:53	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,752 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	I suspect it hasn't collected sufficient data to calculate a meaningful result. The system appears to compute from averages collected over a period of time. If the computer is reset, the calculations it provides are likely to be unrealistic. For the 'best' results, the computer should never be reset. It also uses the calculated mpg data to predict the Range. If the current mpg figure is over-optimistic (which it usually is) then the range will be unrealistic. The mpg data should be calibrated by practical measurement (like a series of brim-to-brim tests) so the displayed mpg matches the actual mpg. There's detail on recalibrating the mpg data in the Diagnostic Mode HowTo. TC