speedo correction math in tuner pro or tuner cats

[cholmes729]

Anybody know the Speedo correction formula for tuner pro or tuner cats.

[MeanTA]

There are two ways to calculate the speed calibration parameters; by tire size or by the number of revolutions per mile of the tire. The most accurate way is to determine the actual revs per mile for your vehicle but you can enter the tire size and the program will calculate an approximate revs per mile. To use tire size, click on the 'Tire Size' option button and enter the tire size in the boxes provided. To use revolutions per mile, click on this option button and enter the appropriate revs per mile. To properly calculate the vehicle speed, the PCM also needs to know how many pulses per revolution of the driveshaft are generated by the speed sensor. If you are using the original transmission, click on the 'Stock Speed Sensor' option button in the Speed Sensor Information Box' and then select the appropriate 'Car Type' and 'Transmission Type'. The Tuner program will then insert the correct value of pulses per revolution. If you are using a non-standard transmission, then you will have to enter in the correct number of pulses per driveshaft revolution for the speed sensor that is being used. To enter in this value directly click on the 'Pulses Per Driveshaft Rev.' option button. This will disable the 'Stock Speed Sensor', 'Car Type' and 'Transmission Type' option buttons and enable the 'Pulses Per Driveshaft Rev.' text box. Enter in the correct value of pulses per revolution for your speed sensor. Finally enter in your rear end ratio. To calculate the new speed calibration parameters, click on the 'Calculate' button. The 'New Calibration Values' box will now display the speed calibration parameters. The 'Current Calibration Values' box displays the current calibration parameters stored in the calibration file for comparison. When you are satisfied with the new values, click on the 'Apply' or the 'OK' buttons to enter these new parameters into the calibration file (just as if you changed them from the Constants Table.) The 'Apply' button applies the changes but leaves the Speedometer Calibration screen open. Clicking on the 'OK' button also applies the changes but closes the Speedometer Calibration screen. Click on the 'Cancel' button to close the Speedometer Calibration screen without making any changes to the calibration file. If you use tire size, you should get close to the correct calibration values but you may have to make some corrections after testing. To then fine tune the speedometer calibration further, use revs per mile to make small adjustments

[MeanTA]

these are instructions for tuner cat.
17152
17153

[cholmes729]

Thanks, I will check it out.

[bobdec]

17206