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Rough Country Speedometer Calibrator

Discussion in '3rd Gen. Tacomas (2016+)' started by alwaysHI, Nov 5, 2018.

  1. Dec 15, 2020 at 4:23 AM
    #121
    JasonT87

    JasonT87 Well-Known Member

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    Lol
     
  2. Dec 15, 2020 at 5:53 AM
    #122
    Kclamer

    Kclamer Well-Known Member

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    2.5" lift, 4.88 gears
    I have the Hypertech module and discovered last month that it only corrects the speed up to a point, once you input a calibration factor that is equal to 1.10 or higher the speedometer will stop working and a bunch of christmas lights will come on. Also after you go higher than 1.05 it really doesn't make a difference anymore so you can get about 5% increase and quite a bit more decrease as I have been able to go as low as 0.80 where the speed readout is over 10mph lower than a GPS reading.

    Also if you follow the instructions and plug in your tire size, gears, original size the formula is way off. I talked with tech support and they told me to just keep playing with tire size until I get a calibration factor that matches a GPS measurement. This is definitely not ideal as its basically trial and error where you have to keep flashing the module until you get it right.

    I have 255/85R16 tires with 4.88 gears and I can get dead on to have the speed readout match a GPS, on my winter tires sized 265/75R16 it is not possible as there is not enough adjustment headroom. All this module does is take in the voltage reading from the speed sensor and adjust it with a calibration factor, it makes a difference on the speedometer and your odometer but not the cruise control as that module gets its own speed reading. So when you set your cruise control it will give you a different speed than what your speedometer shows.
     
  3. Dec 16, 2020 at 4:52 PM
    #123
    poopshute

    poopshute Well-Known Member

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    I just installed the Rough Country version to correct the speedometer readings after installing 285/75r16's. To my pleasant surprise, my speedometer is accurate again. Matches GPS readings on my phone and I tested it against 3 different radar speed signs. Installation was a breeze as well. Pretty sweet! Glad I stumbled upon this shortly after getting the tires installed. No longer need to worry about driving 3 mph slower according to my gauge. I did a quick test of the ODO readings and it appears to be accurate as well. I'll do a better test soon just to make sure.
     
    angelr429, daltondrose, mlr69 and 3 others like this.
  4. Jan 13, 2021 at 1:35 PM
    #124
    TACO TM

    TACO TM Active Member

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    Have you confirmed the odometer was also corrected? I get 50/50 responses to this question so I keep asking people who have done it.
     
    TACOROSSO likes this.
  5. Jan 13, 2021 at 1:40 PM
    #125
    poopshute

    poopshute Well-Known Member

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    This is a good question and my early tests, for shorter trips, showed it to be fairly accurate. The challenge is GPS will always be different compared to the on-board odometer. I think when I tested last, it was off by a fraction of a mile after a 9 mile trip. I'll try it again tomorrow to confirm.
     
    TACOROSSO and TACO TM like this.
  6. Jan 14, 2021 at 11:11 AM
    #126
    poopshute

    poopshute Well-Known Member

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    Ok, tested on an 8 mile trip this morning. Odometer/Trip meter showed 8.0 miles, GPS showed 8.16 miles. I think that's close enough and I'd assume with the stock setup, my 33's would probably have the discrepancy more than a fraction of a mile. Agreed?
     
    TACO TM likes this.
  7. Jan 14, 2021 at 12:08 PM
    #127
    TACO TM

    TACO TM Active Member

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    Man it's hard to say?

    With 32.8" tires you are traveling ~7.2% further than what the odometer displays because it thinks you are on 30.6" tires.

    If it the programmer had not corrected the odometer, your GPS it would have read 8.57 instead of 8.16, but it appears the programmer did correct the odometer to some extent. I think a longer mileage test would yield more accuracy, but also the current error is exactly 2%...so maybe that's as perfect as it needs to be or can be.
     
    Last edited: Jan 14, 2021 at 12:50 PM
  8. Jan 14, 2021 at 12:50 PM
    #128
    poopshute

    poopshute Well-Known Member

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    Agreed with your logic. I’ll take this over nothing at all. At least it gets it more near to stock accuracy. My main concern was for speed-correcting so that I’m not going faster than I think I am. I’m sure you can fiddle with the numbers on the brains but at least it looks like it is indeed correcting (or attempting) the odometer as well. I have a manual transmission 3rd Gen just to add a little extra detail.
     
  9. Jan 14, 2021 at 1:14 PM
    #129
    TACO TM

    TACO TM Active Member

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    For sure man. I edited my earlier post and noted the odo error is exactly 2% Maybe that's as close as it can get?

    The ultimate test to see what the odo is doing...change the tire diameter in the programmer by 2% and do the same distance test again the same way...if the programmer is correcting the odo, then both the odo and GPS would eventually match each other with diameter input changes if it the programmer is changing the odo. Or change it to the extreme to make these results more obvious knowing the speedo is no longer accurate. I totally get if you don't care to do this...just an idea!

    Your trans gears and/or diff gears do not come into play because the sensors read wheel speed.
     
  10. Jan 14, 2021 at 1:39 PM
    #130
    poopshute

    poopshute Well-Known Member

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    Your understanding of how the programmer is correcting the odo sounds accurate to me. You can literally put in any value you want to the new tires (both in inches and metric) to continue to skew the values that show up on your instrument cluster. If I had the time (or cared for better accuracy), I'd definitely tweak it. I know others have done this as well but could only get it to a certain margin of error before going the other direction. I do feel that with my current/recommended settings, the speed is very close to accurate compared to my phone's GPS as well radar speed limit signs. My main concern was not to get pulled over because I couldn't do the math some day while driving. I have two young kids and they have made my brain mush. :D

    With all that said, maybe this is enough for you to pull the trigger and buy one? I think Rough Country has a 30-day money back thing (though you'll probably have to pay for shipping back). Although, even if it is slightly inaccurate compared to stock, it's still much better than running without it if you're running bigger tires.
     
    58electricman likes this.
  11. Jan 14, 2021 at 1:44 PM
    #131
    TACO TM

    TACO TM Active Member

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    Yes sir! I totally get it.

    My only problem is that:
    A. I don't even have the truck yet...build date coming soon...ish..or something like that according to my salesman.
    B. These don't work on the 2021 as something was changed in the connection points. I already asked Hypertech and they input the request to expand product to 2021 "when possible". Ha
     
  12. Jan 14, 2021 at 4:33 PM
    #132
    poopshute

    poopshute Well-Known Member

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    Ah... yes. All makes sense. I'm sure you've figured it out by now but the Hypertech and Rough Country are identical and use the same software to program. I hope they come through with an updated version for you! I would think they would.
     
    TACO TM likes this.
  13. Jan 14, 2021 at 4:35 PM
    #133
    trl1990561

    trl1990561 Well-Known Member

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    Just ordered BFG KO2 265/75/16 will my speedo be off with only going up in size a little? I understand my MPG might go down but hopefully my speedo won't be off.
     
  14. Jan 14, 2021 at 4:39 PM
    #134
    poopshute

    poopshute Well-Known Member

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    It will be off a bit. Not as much as 285/75r16s. Basically, anything other than stock tire sizes will be off.
     
  15. Jan 14, 2021 at 4:41 PM
    #135
    trl1990561

    trl1990561 Well-Known Member

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    Dang ok, the only reason I ordered the bigger size is because (1) the 265/70/16 are out of stock in my area and (2) they are $60-$70 more per tire.
     
  16. Jan 14, 2021 at 5:16 PM
    #136
    TACO TM

    TACO TM Active Member

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    You might luck out. Many members have reported the stock speedo reading too high and after adding an inch taller tire, they say it became more accurate. Let us know!
     
    poopshute likes this.

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