w169 Merc A Class A150 Wrong Reading Trip Computer

[jay786]

Hi,

I duno whats wrong with trip computer coz when i put petrol in and it shows how many miles i have in the tank ... when im stationary it just keeps going down (a mile per 2 secs) as if im losing fuel.
Am i getting wrong reading ... is this a common fault?

For example i put £20 petrol in and it states 193 miles ... 5 minutes later it shows 130 miles ... ??!

Please help

Thanks

 

[GP801]

Does the range go back up again once you start driving? If so thats normal. You are using fuel but going nowhere. (unless of course its dropping with the engine off)

 

[DrNick]

Sounds normal. The computer is trying to predict (guess) how many miles are left based on recent history of use.
If you left it idling on the drive until it used up all the fuel, how many miles to the gallon would you have done?

Its quite instructive to see what the effect of stop/start traffic is on average mpg. (Something to do when bored in a queue)
Answer: A lot!

Cue discussion on merits or otherwise of stop/start technology!

Nick

 

[jay786]

it kept going down and then stuck at one point and as i was driving it goes down as it should.

Yesterday, i put £10 petrol in .... the gauge did not move at all and the mpg stated 13 miles ... same miles before i even put petrol in.
I went back to the petrol pump and i went and complained ... did i actually put petrol in or did i pay for nothing. I decided to put another £10 and then the gauge and the trip computer adjusted.
Is that normal?

 

[nigel cross]

I think that putting £10 of petrol in isnt a great deal, not even 2 gallons.
The mileage range is based on your previous reading, ie starting from cold etc.
Once tha car is warmed up or on a A road take a look at you mpg and keeping at a stady 60 or 70 reset the trip again and the reading will change

 

[jay786]

Hmmm ... fair enough .. so roughly how many miles should i get in a gallon?

i put £15 in and got 96 miles ?

Also ... what engine oil do u recommend for this car:

Castrol Edge 5w-30 or Castrol Edge 0w-40?

Thanks