First of all, let me say that I have NOT YET hooked up the VSS wire for speed sensing to my F90BT. I just didn't have time when I installed it to go digging for the wire.

Issue: When I'm going about 80mph and the map is in 2D mode, every three or four refreshes of the page seem to show my car moving BACKWARDS on the freeway - the direction still shows correctly, but it's like my car timewarped back to a few yards behind me.

Anybody seen this? Will hooking up the VSS wire fix this?

Sounds as if you don't have a consistent GPS fix... And yes, if that is the case, hooking up the Vss should solve this. However, I'd first check if there is a problem with the GPS reception...

I'll monitor my gps reception on the way home today - but it doesn't do this in 3D mode - only 2D.

GPS updates position only once a second. To provide for a smooth map movement, software extrapolates your position based on last known speed. If, when it receives actual GPS data, the GPS position is behind where it extrapolated you would be, it will snap back...

GPS updates position only once a second. To provide for a smooth map movement, software extrapolates your position based on last known speed. If, when it receives actual GPS data, the GPS position is behind where it extrapolated you would be, it will snap back...

So you agree that connecting the VSS wire will resolve this?

GPS updates position only once a second. To provide for a smooth map movement, software extrapolates your position based on last known speed. If, when it receives actual GPS data, the GPS position is behind where it extrapolated you would be, it will snap back...

 

So you agree that connecting the VSS wire will resolve this?

AFAIK, not for the F-series. It seems to only use gyro/VSS when GPS reception is lost. If GPS is there it will default to using GPS anyway. OTOH, connecting VSS is useful for all other reasons.

I am having the same issue with mine. Did you ever get this issue resolved?

No - but I also haven't hooked up the speed sense wire yet either.