I'm a dumb a$$
 

Hey guys I just had my car tuned and I told the tuner that I had 3.42, but I only have 3.23. How far off are my MPH going to be until I have time to go back and get it changed? I feel like such an idiot. :bang:

~4mph slow at 70 (right around 6%) so its not a whole lot, you will put 6% less miles on the car also :)

So if it says that I'm doing 70, then I am realy doing 74, is that correct? Also we set my shiftpoints at 6500 and it is shifting at 6000. I guess that is part of it too? Would this also affect my idle rpm settings? Because I can't get the car to idle for shit now, it's idling too low.

pretty much, depends how far off your speedo is but but just multiply your speed by 1.06 and thats approximately how fast you are going.

The shift points are controlled by two things, mph and RPM, since your speedo is reading lower it may not make the speed needed to shift but thats pretty unlikely (but its possible, setting shift points is kind of a trial/error thing usually and I have seen diffierent tire sizes change WOT shift points) since most people keep the mph for the shift points fairly low and control upshifts with the rpm..

The speedo calibration being that little off has nothing to do with your idle.

ok thanks for the replies