speedo reflash
Thread Starter
2nd Gear Member
Joined: Nov 2006
Posts: 219
From: Oregon
speedo reflash
Ok I just got my T-Lok and gears put in and Im running 19's....its buggin me how off my speedo might be. Are the delaerships able to reflash to make my speedo acurate again? I have to wait a month and a half for my C&L Xcal and I cant stand not knowing if Im speeding or not.
5th Gear Member
Joined: May 2007
Posts: 2,388
From: Central Texas
what gears did you get? Unless if you went with a lower ratio number, like 3.27s or lower (not likely), then your speedo is likely reading lower than actual.
If you can drive on an interstate highway or other road with mile markers at 1 mile increments, you can time your time between the markers: a steady speed of 60mph will take exactly one minute. Or if you have a gps device, you can usually estimate your speed that way too.
Once you get the xcal, you can set it in there. You should also set your tire revs per mile in the tune if the height is different than stock; that will throw the speed off, too a little.
If you can drive on an interstate highway or other road with mile markers at 1 mile increments, you can time your time between the markers: a steady speed of 60mph will take exactly one minute. Or if you have a gps device, you can usually estimate your speed that way too.
Once you get the xcal, you can set it in there. You should also set your tire revs per mile in the tune if the height is different than stock; that will throw the speed off, too a little.
MF Administrator
Joined: May 2005
Posts: 8,193
From: South Carolina
Don't take it to the dealer. I wouldn't trust them to alter computer settings, if they can even do that. Mike is right. Another choice would be to have a friend pace you at 60, and you see what your speedo reads. At least that will work until you install the tune.
The X-Cal settings for Tire Revs Per Miles are as important as selecting the gear, especially if you are running an automatic. Check the website for the tire company of your 19's to see if they list revs per mile for that size, and use that number once you get your tune. You should be able to change the optional parameters with the handheld. Double check with the company doing your tunes to make sure they will unlock those settings (some don't). If you cannot find the listed revs per mile for your size tire, then you will have to calculate it by dividing the tire circumference into a mile. A small variation occurs with this method because the tire's contact patch throws off the actual circumference. So minor adjustments with the handheld may be needed to get your speedo dialed in.
The X-Cal settings for Tire Revs Per Miles are as important as selecting the gear, especially if you are running an automatic. Check the website for the tire company of your 19's to see if they list revs per mile for that size, and use that number once you get your tune. You should be able to change the optional parameters with the handheld. Double check with the company doing your tunes to make sure they will unlock those settings (some don't). If you cannot find the listed revs per mile for your size tire, then you will have to calculate it by dividing the tire circumference into a mile. A small variation occurs with this method because the tire's contact patch throws off the actual circumference. So minor adjustments with the handheld may be needed to get your speedo dialed in.
Cut & Paste Expert
Joined: May 2007
Posts: 13,322
From: NW Arkansas
Get a CAI/tuner and a tune.
Its a win/win situation.
The tuner lets YOU adjust for gears and different
tire sizes for correct speedo readings.
It also has the benifits of a tune to wake up the stang.
Its a win/win situation.
The tuner lets YOU adjust for gears and different
tire sizes for correct speedo readings.
It also has the benifits of a tune to wake up the stang.
Last edited by 157dB; Feb 28, 2009 at 04:30 PM.
Thread Starter
2nd Gear Member
Joined: Nov 2006
Posts: 219
From: Oregon
what gears did you get? Unless if you went with a lower ratio number, like 3.27s or lower (not likely), then your speedo is likely reading lower than actual.
If you can drive on an interstate highway or other road with mile markers at 1 mile increments, you can time your time between the markers: a steady speed of 60mph will take exactly one minute. Or if you have a gps device, you can usually estimate your speed that way too.
Once you get the xcal, you can set it in there. You should also set your tire revs per mile in the tune if the height is different than stock; that will throw the speed off, too a little.
If you can drive on an interstate highway or other road with mile markers at 1 mile increments, you can time your time between the markers: a steady speed of 60mph will take exactly one minute. Or if you have a gps device, you can usually estimate your speed that way too.
Once you get the xcal, you can set it in there. You should also set your tire revs per mile in the tune if the height is different than stock; that will throw the speed off, too a little.
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