Speedometer calibration help

[Ralph67]

I did a quick search but couldn't find exactly what I was after. I just got hp tuners yesterday and am trying to go through a few things. One is my tire size and gear ratio settings to make sure it is not affecting my transmission shift quality. So under the speedometer window I have the "calibration" tab open. So these are the numbers I need to make sure I have figured out:

VSS Pulses per rev - trans.

Trans revolutions/mile

Final drive (3.70)

VSS pulses per distance

Pcm output calibration pulses per mile

Speedo abs ppm.

So any help is appreciated, for what it's worth it's an 05 gm truck ecu, 3.70 final drive, 4l60e, and a 27.3" tire diameter. Thanks!

[5FDP]

Do the gear ratio and tire size match in the gear/tire wizard under the edit tab?

[Ralph67]

I didn't even know about the gear and tire wizard. It's very close, looks like the mail order tune had 3.73 and 28" tall tire. So I will adjust those numbers, is that what the gear and tire wizard is for? Once I enter that it figures out all the other vss pulses etc? Thank you

[5FDP]

Yes, pretty much.

Change the tire/gear and then click auto scale transmission, it will adjust just about everything for you. Of course fine tuning your shift points/pressures and if you installed an aftermarket stall converter will take extra adjustments.

[Ralph67]

Thank you very much I got it figured out now. I see the changes it made.

[ryanh1986]

On my M6 vehicle I used the calculator but it made my ABS light come on. My stock tune (which had been messed with prior to owning the ECU) didn't do this, and since I don't have an auto I wasn't worried about shift points... so I plugged in my cheapo bluetooth OBDII scanner and logged the average percentage the speedo was off vs GPS. Then, I simply subtracted that percentage from my VSS Pulses Per box. My speedo is dead-on now and the ABS light doesn't come on. I might also add that I have a Ford 8.8 rear diff and I haven't been arsed to see which gears are in it yet. Once I eventually find out all the unknowns, I may try it the right way, however this has been working fine.

[Ralph67]

I will keep this in mind if I need to adjust, thanks.

[watman02]

maybe a dumb question but in the gear tire wizard when it ask for tire size it wants hight right?

[Jason B]

in the gear tire wizard when it ask for tire size it wants hight right?

Yes.
Click Tools - unit conversion. In the upper right hand side you can put in your sidewall numbers and get the height from there.