MPG display reading....

[thegoal007]

I recently started to monitor my last 2 fills of petrol with accuracy whilst looking/resetting the corresponding value being displayed.

So the patteern seems to be that the diaplay is out by about 3 MPG. SO in my case I worked out i had done 27 MPG and the display was showing 30.

Is there a VCD approach to re-calibrating or adjusting it manually so its minus 10% ?

NOTE: I use to monitor my MPG consumption religeoulsy when i first got the car for about a year and decided to start again. I dont think back then I ever tried to corrolate with whgat the displayed showed up.
So many years of ownership and very pleased to say it's along the same lines. When most driving is motorway i get even better results.

 

[Stuart B]

10% is quite a lot.. is your speedo also out by 10%?

My Golf TDI speedo is out by 10% it shows 33mph when a community speed watch shoes 30mph, and my MPG shows 64mpg which I think is too high. I have tried changing tyre size to get it correct, you can do that with vcds, but that didn't help.

There are proper calculations for flow rate in the map, I assume you've not changed injectors and not updated the map?

 

[thegoal007]

10% is quite a lot.. is your speedo also out by 10%?

My Golf TDI speedo is out by 10% it shows 33mph when a community speed watch shoes 30mph, and my MPG shows 64mpg which I think is too high. I have tried changing tyre size to get it correct, you can do that with vcds, but that didn't help.

There are proper calculations for flow rate in the map, I assume you've not changed injectors and not updated the map?

I would not know whether the speedo is accurate - i assume it is....failrly!
My tyres are standard for the 17" allolys and so is my BAM engine.
As I read more into this and get educated it becomes an even more complicated subject!

Its OK, I will just live with knowing this.

 

[Dohcwp]

Economy calculation is never accurate its just an estimation, faulty maf or 02 sensors can affect that reading.

to check if your speedo is calibrated correctly do an output test in vcds and the rpm needle should land on 3k rpm when staged and the speedo on 100km/h and both temp and fuel gauges at 90 and half tank respectively

 

[thegoal007]

OK, manaaged to get around and do the test. This is what i see. I make it dead on 65mph so slightly higher than the 100km/h.
Is this adjustable to read precisly 100 ?