Stumped by screwy $^%&*ng odometer...
 

Yes, another odometer post unfortunately... ;) :p

So heres the deal: My odometer doesn't work properly (like most 850's I've encountered lol). I'm starting to suspect that its not my odometer gears that are the culprit. Currently, my odometer is reading about 5x too fast (on a 225 mile trip it read about 1100 miles travelled, give or take). Trip meter is acting the same way.

The following day after driving that 225 miles, the odometer quit reading altogether for about 35 miles. After I laid a bit of tire gunk on the road while winding up the turbo a bit in sport mode, the odometer gear kicked back in and decided to start working "properly" (i.e., 5x too fast) again.

I'm stumped with this problem. Almost seems like a speed sensor issue...Does anyone have any ideas? Its driving me bat crap crazy watching the miles tick off and it makes it difficult to keep track of my maintenance log and mpg (short of following the trip computer in the info center, which works perfectly fine and counts the miles off properly 1:1). No codes stored though in the tranny computer or OBDI port for speed sensor short, etc... Has anyone run into this issue before?

curious if you can have access to a VIDA DICE unit to read the true mileage out of the CIM to see if the data is bad (ie bad input from a sensor or system component) or its mechanical (ie odometer digits )...

possibly. its a long shot but i have a buddy that runs a euro only indie garage, I ***think*** he has a VIDA DICE system. Gotta go see him in a few weeks anyway, I'll double check and see. The obdI system reads out just over 218k miles. I suspect that it is correct, but not sure why the odometer reads 5x fast. I do know the previous owner upgraded the turbo and the ECU on this car, and also has 205-55/16 tires on the car (which would explain in part of why the odometer reads fast, but not 5x fast)....planning to change over to 205-50/16 tires in the near future when these continentals are shot...

Judging by the autocheck/experian report on the car though, 218xxx miles seems to be correct though. Last reported mileage was 180k or so about 4-5 years ago, and given an average of 10k a year it seems pretty close....

I have a used cluster from a '95 (needs the odometer gear) if you want something to play with. It takes less than an hour to swap out the cluster (done this on a couple of 850Ts fixing the odometer gears) so you can try shopping for a replacement even if its to swap for a test...