Monday 20 October 2014

TOYOBD1 Android Datalogger :: Correct speedometer error due to wheel size

Sometimes in life you get to wear shoes that are too big or too small, it happens to cars too,sometimes by choice, sometime out of necessity...

In TOYOBD1 you can configure the application to take into account an 'incorrect' wheel size.
doing so will make sure the MPG calculator and speedometer input is accurate.

the Speedometer correction factor can be adjusted in the 'Configure Displayed fields' dialog.
the value must be a positive value greater than 0.0
correct wheel size value for your ecu would be 1.0

 Here`s a good example, my own car! wheel size is way off from what the ecu is expecting.
AE102 corolla, 3VZ-FE V6 and MT Camry transaxle, ae102 wheels

this car needs a 0.85 wheel size ratio to get correct speed and MPG figures in TOYOBD1.
Fact is, the corolla wheel size is in the 185/65/14 range but the native CAMRY wheel size is in the 205/65/15 range.

To find out what is the correct wheel size ratio I use a GPS device to find out constant speed at around 100kmh / 60 mph and adjust the ratio as needed in TOYOBD1 to see the results. (Please don't endanger yourself doing everything alone, ask a friend) When you have found the correct ratio try it at various constant speeds to make sure it still fits with GPS readings.

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