4L80E Swap - Commanded shift MPH is not equal to actual shift MPH

[Super73]

Hi everyone, hoping someone can help trouble shoot this with me.

We have done a segment swap and all gears function properly from a physical stand point, they just don't line up with what the tune is showing.

The other thing I notice is TCC PWM is commanded even before the 1-2 up shift is made.


Attached is the current tune and the latest log.

The only things that are different from the stock 80E file I used (also attached) are:
1) The Sensor Calibration --> VSS Pulses per mile.
2) Gear & Tire Size
3) Gear ratio

Changing the VSS Pulses per mile was the only way I could get the speedo to be accurate. I tried Gear Ratio & Tire Size with the correct 3.73 gear but it was way off from GPS and this was moving it either direction. Not sure if this is screwing me up.

Stock file I used has 111,684 in VSS Pulses per mile
With 50,602 speedo and log file is dead on to GPS


Truck has a 32" tire and 3.73 gears.


408 with stock 80e.hpt
8.4 2nd run.hpl
80e.hpt


Any input would be greatly appreciated.


Shaun

[5FDP]

Using the gear tire wizard under the edit tab, neither tune had correct values for tire size and gear ratio. One was 29in tires and 4.10's, the other was 59in tires and 3.73's.

[Super73]

Haaa.. I feel like a dummy. I could not find the calculator with the newer version of the editor... This should make life easier I was manipulating fields with a dart board approach until I got speedo lined up with GPS.

VSS set to 94,035
GR & TS set to 2,349
Gear ratio set to 3.73
Let's see if this helps

[Super73]

Updated the tune with the tire/gear calculator, please see attached.

Speedo reads 54% of what GPS says:
Truck at 20mph ? gps at 37
Truck at 40 ? gps at 75


Looking at where the commanded shifts are against the tune, it appears to line up with each other but in reality it is shifting at a much higher mph due to the speedo and datalogger reporting inaccurate mph. What ever datalogger reads divide it by .54 to get to the actual MPH. Please see attached for examples.



Any thoughts?

[Super73]

Still trying to figure this out. Any thoughts?

Why is the speedo and datalogger so far off from the GPS if tire/gear ratio is corrected in the tune?

[Super73]

Any one?? Staff at HPTuners?

[5FDP]

My only other suggestion is to try the segment swap over.

Start fresh, apply the segment swap with a known good file or even a different file from what you previously used. Apply the rest of your changes to the gear ratio and tire size. Flash the tune and see what you come up with.