Big discrepancy between FIT and GPX file total distance, and as displayed on Trip Computer

This matches one of several distance error issues I'm having on my 66st. Trip Computer distances are often far too high compared to other measures (PC mapped MS Streets & Trips distance measure for walks, my old 60csx and car odometer for a drive).

A recent neighborhood street walk measured 3.7 miles on the trip odometer, whereas MS-S&T said 2.7.  (Spouse's FitBit was much closer to the later).  Pulling up the track log in Basecamp, the log initially showed 3.7 miles.  But deleting a single point, the very last, shortening the track by merely 3 feet, caused Basecamp to refigure the distance as 2.7 miles, matching MS-S&T and my sense of reality.

Several prior walks in the 3 to 6 mile range displayed similar patterns, dropping to a realistic number after any sort of editing of the track file.

A weekend trip one-way drive for an elder care work shift measured 404.9 miles on the car's odometer, 403 miles on the 60csx, and 631.0 miles on the 66st.  Looking at the 66st track file, it contained four separate momentary giant leaps backwards, of 32 to 46 miles each.  The first two were clearly associated with rest stops, where I turned on the display to check it.  The later pair were while moving, but could be associated with checking the display on long empty rural highway.  There were some additional smaller anomalies too, including a repeated position while driving at 60 mph, and a 290 mph claimed speed between two logged points.

Top speed of this trip: 137444 mph according 66st's trackfile, 71.9 according to 60csx, 74 was highest observed on car speedometer.  66st's Trip Computer also claimed a higher average than max speed: average 81.8, max 63.7.

The 66st had Battery Saver turned on, Expedition Mode set to Auto, satellites GPS+GLONASS.  Both units had track recording frequency set to least for the drive.  Walking was done at Normal.  I'm still learning on this new unit, so may not have everything set right.  Since the Expedition Mode has been called out in some past bugs, I'll turn it off for the next driving test, next week.

Firmware 6.0.

Thanks.  I'm sending on to customer support.

Looking closer at available files, I just now notice that the car trip is recorded in two separate track files, marked with the same icon in Basecamp.  As a newbie on this unit, I hadn't noticed that before. My old 60csx wrote only one version to its microSD card, a *.gpx.

On the new unit, one track file is labeled in the same format mentioned above as FIT format, and that is the one with the multiple momentary giant leaps backward.  And it also seems to be the one that provided data to the trip computer page.  The other is labeled in the same format mentioned as GPX, and it doesn't contain those momentary giant leaps.  When displayed on a map, the GPX version looks clean.

Both files open with an excess total distance, before editing, but the FIT version has a larger excess.

There is some added confusion from my 66st's tracks including a few extra points from the previous day's outing, from just after saving an activity track but before shutting it down.  But that accounts for less than a quarter of the excess total distance initially displayed from the unedited track files.

This is actually a known issue, many Garmin devices are currently having issues with the *.FIT file recordings. I believe they are working on a correction, but we will have to wait and see....

To followup, I drove that same route in reverse today, but with Expedition Mode turned off (set to Never).  This seems to have fixed the Trip Computer problem:  My 60csx and 66st show matching trip distances, at least to the limits of their differing display resolutions.  And both were only slightly different than the car's odometer, which currently has snow tires instead of the A/S tires it was calibrated for at the factory.

I haven't yet reviewed the track log files, that will have to wait a few days.  Logging rate was increased from Least to Less on both units, but hopefully that does not interact with the Expedition Mode problem.

Thanks, appreciate the update,  - as the problem is not solved with v8.10

Hi hope you are okay , still looks like the problem is still there will incorrect elevation and distance data in the .fit files compared to the .gpx, did you receive anymore updates from Garmin about a firmware update ? Kind regards

Firmware version?