ECM values for MPH about half of actual
ECM values for MPH about half of actual Finally getting into tuning everything and notice that even when I enter the correct values for my tire size and axle ratio (deablosport predator tuner) and compare that to GPS it's nearly half of actual speed.
Even to verify I've used various calculators and used my values and compared them to what I know the rpm is at 60mph and it confirms my numbers.
Is this a known thing or should I triple triple check my numbers?
The numbers
axle 3.41
tires 255/50/17
.62 6th gear
engine rpm @ 60MPH = 1550
Even to verify I've used various calculators and used my values and compared them to what I know the rpm is at 60mph and it confirms my numbers.
Is this a known thing or should I triple triple check my numbers?
The numbers
axle 3.41
tires 255/50/17
.62 6th gear
engine rpm @ 60MPH = 1550
Last edited by rotor vs. piston; Jun 11, 2013 at 09:52 PM.
Sounds like the PPM counts to speedometer are incorrect. Dakota digital makes a unit that will allow you to match the PPM's sent from the GM PCM to your speedometer. Of course, I have a$$umed that you are using the Toyota speedometer.
Wish that was the issue, but it's the stock (to the swap) VSS signal to the ECU. And the ECU is reading that at about half actual vehicle speed... probably will have to keep testing and flashing until it's right or close enough.
OK, then it must be a calculation issue. I know that doesn't help, but, same PCM, speedo, trans, known rear end & tire size...
