I would say it doesn't matter that much it can't be completely accurate because the speedo isn't completely accurate hence the reason why people say your aloud 10% on top of your speed if you are caught speeding to allow for inaccuracy's. Your speedo isn't calibrated like HGV are.

 

If people want an accurate reading then you will have to do the brim to brim test. Regardless if your motor is running right you should get similar to every other BLT or ASV Fabia.

It's not possible to change it on a Fabia as far as I'm aware. Newer VAG cars, certainly, but not the Fabia Mk I. If you know the relevant location then please share because there are LOTS of BLT owners who want to true their stupidly optimistic mpg displays.

I practically begged Ben at Shark to remap it so it read true but it's not a remappable routine in the ECU unfortunately.

I thought it was a value change in some block that could be done to change it roughly, in the same way you can change how the speedo reads, maybe it's something along those lines if the value it provides is part of the calculation? VCDS is a bit of a mystery to me tbf. Light just came on today, so have filled up (vented again) after 713miles and took 50.37 litres (at 93.9ppl ), works out as  64.26mpg, trip 2 read as 70.8mpg, making mine 10.12% optimistic. Not far off what was expected.

You'll have to forgive me, but that's miles out. My A6 with a correction factor of 103% applied in VCDS is accurate to 0.2MPG.

The car counts the injector pulses per revolution of the wheels (vRS only - other Mk I's use a gearbox sensor) and it should be very accurate. But they cocked up the calculation and fixing it would require one of the comfort modules to be replaced with one with the correct calculation built in.

I would say it doesn't matter that much it can't be completely accurate because the speedo isn't completely accurate hence the reason why people say your aloud 10% on top of your speed if you are caught speeding to allow for inaccuracy's. Your speedo isn't calibrated like HGV are.

 

If people want an accurate reading then you will have to do the brim to brim test. Regardless if your motor is running right you should get similar to every other BLT or ASV Fabia.

I think you'll find the speedo is VERY accurate on a vRS because it's driven off the wheels. In Germany the speedo has to be accurate to 2% so I think you'll find that your speed IS your speed. You're allowed 10%+2mph by the Association of Chief Police Officer's guidelines but that's applied at the discretion of the police officers concerned as the calibration of their equipment is checked every day before they use it, so if you're doing 31 in a 30 zone they can prove it but if they did everyone for 31 in a 30 zone they'd spend their whole lives writing tickets. So they cut us a bit of slack once in a while.

And the MPG should be very precise. It's calculated from the injector pulses and the revolutions of the wheels at the ABS sensor so it should be bang-on but it's not because they cocked up. They admitted it in 2006. But they said as it wasn't THAT bad it wasn't a significant defect and they weren't going to do anything about it.

My first vrs under read. And the new one over reads but by only a few mpg.

I thought it was a value change in some block that could be done to change it roughly, in the same way you can change how the speedo reads,.

Sorry to post again, but can you change the speedo in software? Do you know anyone who can do it because I know someone who needs that done!

Sorry to post again, but can you change the speedo in software? Do you know anyone who can do it because I know someone who needs that done!

 

I found it on here ages ago for my older Mk1 Octy. It's not a fine tune as I said, it seems to change it in massive chunks. Can make the speedo under or over read massively if changed to wrong setting. The wheel sensor pulse rate was changeable also somewhere else? 

You can alter the fuel computer on basic mk1 Fabias, but not the VRS :(

Mine is now telling my average mpg is 29mpg on my DSSR nozzles

Working it out really it's doing just over 40mpg

You can alter the fuel computer on basic mk1 Fabias, but not the VRS :(

Mine is now telling my average mpg is 29mpg on my DSSR nozzles

Working it out really it's doing just over 40mpg

Thats a good way for it to be reading under rather than over