Calibrating speed in Tunerpro RT V5
07-20-2010, 10:14 PM
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Calibrating speed in Tunerpro RT V5 After spending half of my Sunday, I figured out calibrate my speedometer. I will go through the steps on how to achieve the correct speed for your speedometer.
First off, find out if your speedometer is displaying the correct speed and if it isn't find out how much it is off and if it is showing faster or slower than your actual speed. There are a few methods of doing this.
The most simple would be to drive next to a car that you are sure that it has the correct speed (in other words, stock gears, stock wheel and tire size, etc.) and have them drive at a certain speed and put their car on cruise control if they have it, drive next to their car and see what your speed is. This is the most common but their is a greater margin for error and the speedometer on the car you are using couldn't be off as well.
Another method would be to use a radar gun or one of those road-side signs that tell your speed. Drive a certain speed and put your car in cruise if it is equipped with it and drive past the radar device. Once again, the margin of error isn't that small and you don't know if the radar has been calibrated and is showing the true speed.
Last method and most accurate would be to use a GPS. NOT and Iphone or other internet based GPS, but a true gps that shows the true speed. Set your car on cruise or keep a steady speed and compare the two.
Okay now you have found your difference and it's time to calibrate your speedometer. For my car, it was off 10 mph positive (it would show 10 miles and hour faster than the actual speed. EX: actual speed 65mph, speedometer 75mph)
To change the speedometer, open up Tunerpro. Press F6 and you will have the parameter tree open on your left. Select "Scalars" and find "Speedometer Scalar". On my stock tune the value was 12.00. What I figured out is that for every 1 digit you go up, it will decrease your speedometer but 5mph and every digit you go down the speedometer will increase by 5mph.
So what if you want to change a number that isn't 5mph? Then you would change the value by .20 for every mph. If you remember, I had my speedometer showing a 10mph positive difference so I needed to change my number (12.00) to 14.00. However, it was still 1mph positive so I changed the value to 14.20 and I was golden.
I sure hope this help some of you out there, but that's how I figured it out. I just don't know if it is the same with all ECMs.
First off, find out if your speedometer is displaying the correct speed and if it isn't find out how much it is off and if it is showing faster or slower than your actual speed. There are a few methods of doing this.
The most simple would be to drive next to a car that you are sure that it has the correct speed (in other words, stock gears, stock wheel and tire size, etc.) and have them drive at a certain speed and put their car on cruise control if they have it, drive next to their car and see what your speed is. This is the most common but their is a greater margin for error and the speedometer on the car you are using couldn't be off as well.
Another method would be to use a radar gun or one of those road-side signs that tell your speed. Drive a certain speed and put your car in cruise if it is equipped with it and drive past the radar device. Once again, the margin of error isn't that small and you don't know if the radar has been calibrated and is showing the true speed.
Last method and most accurate would be to use a GPS. NOT and Iphone or other internet based GPS, but a true gps that shows the true speed. Set your car on cruise or keep a steady speed and compare the two.
Okay now you have found your difference and it's time to calibrate your speedometer. For my car, it was off 10 mph positive (it would show 10 miles and hour faster than the actual speed. EX: actual speed 65mph, speedometer 75mph)
To change the speedometer, open up Tunerpro. Press F6 and you will have the parameter tree open on your left. Select "Scalars" and find "Speedometer Scalar". On my stock tune the value was 12.00. What I figured out is that for every 1 digit you go up, it will decrease your speedometer but 5mph and every digit you go down the speedometer will increase by 5mph.
So what if you want to change a number that isn't 5mph? Then you would change the value by .20 for every mph. If you remember, I had my speedometer showing a 10mph positive difference so I needed to change my number (12.00) to 14.00. However, it was still 1mph positive so I changed the value to 14.20 and I was golden.
I sure hope this help some of you out there, but that's how I figured it out. I just don't know if it is the same with all ECMs.
