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Tweaking with Forscan - Will it explode?

Old 02-10-2019, 08:56 PM
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Default Tweaking with Forscan - Will it explode?

Will putting a wrong setting on my axle ratio on forscan break something?

I have a speedometer inaccuracy of 6-8mph on my 2013 F150 FX2. My understanding is that these are generally caused by changes in tire/wheel size or gear ratio. The rear end was damaged and repaired 2 owners ago and I suspect the gear ratio was changed during the repair. When I hooked up forscan it was set on 3.31, but according to a tattered sticker on the axle the ratio is 3.73. The truck already has the correct tire settings.

I have changed the setting on forscan. Too late tonight for a test drive. I ASSUME that if this is incorrect the only negative effect will be an inaccurate speedometer/mpg readout. I am not an auto expert and I don't want to change some setting that's going to cause my transmission to grind up. Your input is appreciated. If I donít hear anything Iíll just drive it to work tomorrow morning with speedometer app open on the phone and see how close they match up & cross my fingers hoping nothing breaks.


Drove it this morning. The change in settings seemed to have no effect on the speedometer error. Not quite sure what to try next. Suggestions?

Last edited by sharps99; 02-11-2019 at 10:09 AM.
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