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Hey guys,

I just bought this Jeep used from a dealer and the speedometer was never calibrated correctly. I purchased the Superchips flash cal f5 and it calibrated the right tire size but not the speedometer. So Superchips did some testing and sent me an upgrade to the trailcal. Same results.

Wondering why its calibrating everything but the speedometer?

Thanks,

Mike
 

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I believe the speedometer adjustment is a reflection of the tire size you input.

Measure the actual tire size you have, input that into your Flashcal. Use a GPS speedometer app on your phone. Verify it is close to the speedometer on your dashboard. If not, adjust the tires size up and down accordingly.
 

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Discussion Starter #3
I believe the speedometer adjustment is a reflection of the tire size you input.

Measure the actual tire size you have, input that into your Flashcal. Use a GPS speedometer app on your phone. Verify it is close to the speedometer on your dashboard. If not, adjust the tires size up and down accordingly.
I already did those things. what im getting is the gps is about 7-8 mph slower than the speedometer. which tells me the calibration did not help fix the speedometer but did change the tire size. these things were already looked at by the techs at superchips.

However, I'm trying to see if anyone knows why the speedometer isn't correcting when everything else did?

thanks
 

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First how are you verifying that "never calibrated correctly"?

Remember don't just think that a "35" tire is actually 35". It is trial and error, start about .5" below what the tire is advertised then like Shadowmaker said compare to a phone GPS ap and then adjust as needed.
 

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First how are you verifying that "never calibrated correctly"?

Remember don't just think that a "35" tire is actually 35". It is trial and error, start about .5" below what the tire is advertised then like Shadowmaker said compare to a phone GPS ap and then adjust as needed.
This is the correct way to do this.
 

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Discussion Starter #6
First how are you verifying that "never calibrated correctly"?

Remember don't just think that a "35" tire is actually 35". It is trial and error, start about .5" below what the tire is advertised then like Shadowmaker said compare to a phone GPS ap and then adjust as needed.
I measured from the ground up on the tire. got 33.5". calibrated that to 33.5" on the jeep. they said it took to 33.5" but my speedometer is still showing mph is off compared to the gps. mileage is correct and tire size is correct. speedometer is showing off. 7-8mph. calibrated to stock and went all the way to 40" inch tires. nothing changed on the speedometer. went to the computer and uploaded my data to superchips.

just trying to see if anyone is having the same problem. not trying to re diagnose. Something isnt taking on the speedo.

thanks again
 

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Oh... that could be a Superchips issue. It now sounds as if the programmer is not transfering the settings.
Yes. thats why they sent me a new unit with different software. the new unit still didnt take.

I am wondering if anyone else has had the same issue and what they did or who they used(manufacture of calibrator) to correct this issue.

Best
 

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It looks like that you already are in communication with Superchips, I'm assuming you updated your unit with a computer.
 

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It looks like that you already are in communication with Superchips, I'm assuming you updated your unit with a computer.
Yes, this is also how they receive the information from what i did to my vehicle was through there updating software.
 

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Have you been able to program any other function? See if you can successfully change how long the interior lights remain on after you exit and close the doors. Just trying to see if its only an issue with the speedometer or the unit itself.
 

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My first impressions was that the speedo was swapped out from the Jeep. Did you purchase from a Jeep dealer or a used car lot that gets auction vehicles?
Also, take a look at the car fax.
 

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If it was a 2nd hand JK, have the diff ratios been changes as well?


You say it is off as, "gps is about 7-8 mph slower than the speedometer". Is that a constant, or does it scale with speed?


If scaled, it seems to indicate you either have, say, either smaller tyres than the Superchips measurement, or the diff ratio is, perhaps 4.1 instead of 3.21, or 3.78.


When I changed mine, I used the measured circumference, (that's what the Aeroforce gauges work on), as a starting point, then adjusted until it was accurate & ignored what it thinks it is. I treated the 'measurement' as just a number to be adjusted for accuracy.
 

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Does it transfer data with a simpler change? Say... TPMS on/off or DRL on/off?



Whoops... Dupe from above...

Have you been able to program any other function? See if you can successfully change how long the interior lights remain on after you exit and close the doors. Just trying to see if its only an issue with the speedometer or the unit itself.
 

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Im with Nemo, sounds like diff ratio. Had that issue with a Nissan Titan i owned, speedo was off after new tires, tuned, and tuned, and did the whole trouble shooting thing only to find-out the truck had the tow package, which was a different diff ratio than was default in the programmer. Reset the diff ratio with tire size, fixed.
 

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Hey guys,

I just bought this Jeep used from a dealer and the speedometer was never calibrated correctly. I purchased the Superchips flash cal f5 and it calibrated the right tire size but not the speedometer. So Superchips did some testing and sent me an upgrade to the trailcal. Same results.

Wondering why its calibrating everything but the speedometer?

Thanks,

Mike
You need to make sure it is programming the correct gear ratio. I'm pretty sure the F5 can do this but you have to know your gear ratio first.

Its possible the previous owner changed the gears but I would start with stock numbers.
 

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I measured from the ground up on the tire. got 33.5". calibrated that to 33.5" on the jeep. they said it took to 33.5" but my speedometer is still showing mph is off compared to the gps. mileage is correct and tire size is correct. speedometer is showing off. 7-8mph. calibrated to stock and went all the way to 40" inch tires. nothing changed on the speedometer. went to the computer and uploaded my data to superchips.

just trying to see if anyone is having the same problem. not trying to re diagnose. Something isnt taking on the speedo.

thanks again
Is this the stock built in GPS, an aftermarket GPS, or an external GPS? I ask because the stock built in GPS gets its speed from the same place the speedo does.
 

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Discussion Starter #20
If it was a 2nd hand JK, have the diff ratios been changes as well?


You say it is off as, "gps is about 7-8 mph slower than the speedometer". Is that a constant, or does it scale with speed?


If scaled, it seems to indicate you either have, say, either smaller tyres than the Superchips measurement, or the diff ratio is, perhaps 4.1 instead of 3.21, or 3.78.


When I changed mine, I used the measured circumference, (that's what the Aeroforce gauges work on), as a starting point, then adjusted until it was accurate & ignored what it thinks it is. I treated the 'measurement' as just a number to be adjusted for accuracy.

The gear ratio is fine. Like I said in a previous post. All is correct when it comes to the computer readings. The only thing not working is the speedometer which I’m having the dealer look at at this point since it wasn’t working correctly when I bought it from them with the upgraded 35’s.
I’m not trying to rediagnose anything. Just looking to see if anyone on here has heard of this happening.

Best,

:beerme:
 
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