waggz

So I'm a 100% nooooob to messing with the tune on my car. Before I can really learn the art of tuning I have a few issues that I need to address and one of them seems to possibly involve a gear change we did.

I looked around a bit and didn't see any guides on this so I'm hoping someone can help. How/where in EFI live will I change the gear ratio? We went from a 3.70 to a 3.50 and I need to make that change in the tune I think to address an issue and fix the speedo.

Do I have to pull the whole tune, change it, then stick it back in? I have no idea how to do that and I don't want to brick the car.

PeteS160

What type of Pcm, if it's a P01 or P59 it's pretty hard to miss if you looked under the tab makers Speedo. If it's something newer you'll need to look at the TCM to find that data. Knowing what type computer your working on would narrow it down and I can post a screen shot.

waggz

It's a 2000 trans am

PeteS160

On the left side of the menu open the tree Speedometer and then click on Parameters. Click on "Speedo Calculator" and the new box will open. At the top enter the tire size information and click the button next to the Rim box with the circular arrows. Then enter the gear ratio in the box that says Final Drive Ratio. Click Apply and it will update the data in the speedo parameters menu with the correct information and your done.All the information has been updated and will now reflect the correct tire size and gears and your done. Flash the calibration only back to the pcm and your finished.

joecar

Just in Case:

if it complains about permissions when saving the tune file, then close the tunetool, right click on it and select "Run As Administrator" and go back in to the Speedo Calculator and do again.