inaccurate speedo

[big_joe]

Hi all. Does anyone have issues with inaccurate speedometer readings on their Ek9? Mine seemed to be really under reading so I checked it with a Gps. It's still in KPH and a true 70mph on the Gps is 130k on the clocks, should be 112k if my maths is correct. I know speedos are never accurate but 20kph seems excessive. Also none of the needles on the dials dont light up so I can barely see them at night.....I wonder if this is connected? Was wondering if someone might have been messing about with a speedo converter previously or something? Any ideas?

 

[nfspeedy]

Hi it must be your tire size. I run 195/50R15 and the speedo shows exact 10km/h more than I measured with the GPS. I tried 30km/h, 50km/h and 70km/h with the GPS and the speedo showed exact 40km/h, 60km/h and 80km/h.
Original tire size is 195/55R15. I didnt go faster with the GPS but it is possible that it is more than 10km/h over the speed of 100km/h.
The same with my EJ6 Coupe because I also run the EK9 speedo in it.
regards
Oliver

 

[big_joe]

I'm running 50 profiles surely that wouldn't change the rolling radius enough to affect it by 20kph?

 

[dk11290]

Yeah your not alone on that mate. I think Mines varies from 10 kph to 20 kph out the faster I go, changed the vss sensor no change. Also used 15, 16 & 17" wheels with no change.