mpg irregualr readings on computer

[Smeeagain]

My dash computer has started throwing up irregular mpg readings - ranging from 47mpg to 85mpg (if only!)
Any idea what is causing this please?
Its a 2004 E53 X5 3.0d sport
Thanks
Smee

[Turks]

Is your fuel guage working properly?

Otherwise it could be a sensor on your fuel line / rails...


Turks.

[Smeeagain]

fuel gauge is fine as is the 'range' reading on the computer - just the numbers are off the scale !

[Turks]

I think there is a sensor somewhere on the fuel line / rail or on the pump itself which tells the ECU how much fuel is going to the engine, if this isn't working properly it would give the wrong information to the Computer which is why you would be getting the strange readings.

The range is just a calculation made by the computer by the amount of fuel in the tank.

I don't know enough about this sorry to say whether it would have an effect on the actual air / fuel mixture.

Maybe try a reset by un-hooking the battery for 10 mins.


Turks.

[Smeeagain]

thanks - my next question was to ask about soem kind of reset

Will disconnecting the bettery do anything esle ie will I need radio codes etc (which i dotn know as I bought the bar secondhand a couple of months ago) - will the reset have an impact upon anythgin else at all ?

smee

[Smeeagain]

This seems to have sorted itself - which is good and bad - hate intermittent problems that you dont get to the bottom of !

I'll keep an eye and report back

Smee