The largest and best supported Jaguar cars enthusiast site on the Internet!

Serving Enthusiasts since 1993
The Jag-lovers Web

Currently with 3,166 members

Jag-lovers' Ebooks
- Jag-Lovers' xj40 Ebook -

6.13 - Trip Computer (early models) ( Pete Crosby,  December 4, 2001 )

Don't give that little computer and the Jag engineers too much credit with regard to range.

It seems that the range shown is based strictly upon the amount of fuel the computer thinks is in the tank (based upon the level and NOT based upon fuel usage calculated from injector "on" time) and the currently calculated average fuel economy (which IS calculated based upon miles traveled and injector "on" time). Hint: check your range after filling the car up but before you reset the computer. It will calculate the range based upon the current average MPG and the amount of fuel it decides is in the tank, as read from the level sensor.

Average speed is calculated from engine run time and distance traveled.

Fuel used is calculated from the amount of time the injectors are open (i.e. injector "on" time). This is why dirty injectors or a bad fuel
pressure regulator will cause the computer's calculation of fuel usage to be way off when compared to how much fuel it actuall takes to refill the tank.

Instant fuel economy is calculated using injector "on" time and distance traveled and is recalculated about every 5 seconds.


sepbar.jpg (3094 bytes)

This section currently maintained by Pascal Gademer; questions, comments, submissions and suggestions, email


Please help support the move to the new site, and DONATE what you can.
A big Thank You to those who have donated already!



Go to our Homepage
Improve your Jag-lovers experience with the Mozilla FireFox Browser!

  View the latest posts from our Forums via an RSS Feed!

Jag-loversTM Ltd / JagWEBTM 1993 - 2022
All rights reserved. Jag-lovers is supported by JagWEBTM
For Terms of Use and General Rules see our Disclaimer
Use of the Jag-lovers logo or trademark name on sites other than Jag-lovers itself in a manner implying endorsement of commercial activities whatsoever is prohibited. Sections of this Web Site may publish members and visitors comments, opinion and photographs/images - Jag-lovers Ltd does not assume or have any responsibility or any liability for members comments or opinions, nor does it claim ownership or copyright of any material that belongs to the original poster including images. The word 'Jaguar' and the leaping cat device, whether used separately or in combination, are registered trademarks and are the property of Jaguar Cars, England. Some images may also be Jaguar Cars. Mirroring or downloading of this site or the publication of material or any extracts therefrom in original or altered form from these pages onto other sites (including reproduction by any other Jaguar enthusiast sites) without express permission violates Jag-lovers Ltd copyright and is prohibited
Go to our Homepage
Your Browser is: CCBot/2.0 (, IP Address logged as on 27th Jun 2022 05:06:53