I picked up a programmer cheap as heck used. The main reason why I did was because I had 3.73's installed, and when I had a shop edit the pcm for it, they ajusted the ratio change, but not the shift points

So the car would hit revlimiter before the 2nd-3rd gear shift. Well now with the programer, I've fixed the issue, and the car shifts fine. I didnt add or choose the shift firmness, or powerprograming options to on, cause of what I heard in the past.

But I noticed that my shift tables have changed even under part throttle shifting. Which seem logical because before I was probabaly shifting on the 2.73 shift tables (my old gears). Well the yesturday I went through one of those radar stations next to the road that cops setup to show peoples speed so they slow down. And according to it, my speedo is off about -4 or -5 mph. (wasnt like this before the programming). Im wondering if this is because of the tire hieght I selected in the HPPIII settings?

So what tire height do you all have selected for your cars? Im running 245/50/16. Which should be a 24" tire if Im not wrong. Does anyone on here with 3.73s w/HPP3 know what tire setting they have theirs on?

Thanks in advance,
Mike

 

a 245/50/16 tire has a diameter if 25.6 inches

 

stock wheel 16x8 with 245/55/16 should be about 26.1"

jesse

 

lol which one?

 

 

Lay out a measuring tape on the ground, find a reference point on the tire, and roll it forward one revolution to get the circumference. Diameter=circumference/3.14159 If you want to get it exact.

 

well I did measure tire from height from top to bottem. And it was a little over 24 inches. But I think I need to set the programmer height to somthing else. In order to correct the speedo.

Mike

 

The stock tire on the F-Bodys with the Z-rated tire option was a 245/50-16, with a diameter of 25.65". That is what you will find programmed in the stock PCM.

 

thanks folks. Im going to play with the tire heights, and hopefully that radar unit is still up. So I can get it right.

Mike