2013 Mustang GT Power Loss at 6000rpm 5th Gear only

[zajac]

On my 2013 Mustanbg GT 5.0L MT82 6 spd, this year at the track is the first time I have noted a immediate power loss on track while on the full main straight at the Utah UMC (formerly Miller) at almost exactly 6000rpm at about 134mph. All other sections of the track it is a normal acceleration to 7000rpm (7200 rev limit) in 3rd and 4th gears. In all 4 sessions on May 06, 2023, the exact same immediate power loss problem occurred at the same 6000rpm and 134mph. NASA TT2 Group
What is going on and what has changed since last year at the track? Two items I changed.......
1. I changed the gearing from a 3:73 Torsen to a 3:55 Torsen.
2. I switched my driving mode selection from 2013 Mustang GT "Sport Mode" (ABS became too intrusive) to AdvanceTrac Off/disabled/ (ESC Stability off/disabled, Traction Contol off/disabled, ABS sytem functional).
3. I have always run my AED Performance Tune in my 2013 Mustang (AED Performance Tune does not disable AdvanceTrac/Traction control. I am looking to revise my tune to AED Track Tune, AdvanceTrac off/Traction Control off.)

Everything else was normal except for immediate power loos at a consistent 6000rpm/134mph on the full main straight at UMC.
Ideas? Suggestions?

 

[TMSBOSS]

I googled 2013 Mustang GT speed governor and found that the factory programs a 135mph limiter. Google could be wrong. I would look into that first.

 

[zajac]

Thank you. I was trying to find out about an ECU mph limiter. However, it would seem that the mph limiter only surfaced on the more advanced "AdvanceTrac Off" mode selection with the 3:55 gearing? When selecting the "Sport Mode", like I did all last year, there was not a mph limiter intrusion and I could hit the 7200rpm rev limit and about 141mph. However, I had to short shift into 6th gear to avoid the 7200 rev limit....before I came to the end of the straight. That is one of the reasons I switched to the 3:55 gearing as l to be able to stay in 5th gear throughout the main straight...nice except for the power loss at 6000rpm/1`35mph. I would have expected a ECU max mph to surface in the "Sport Mode" rather than the more advanced driving style with AdvanceTrac off/disabled. Still searching.......

 

[Dave_W]

Did you program the ECU for the gearing change? If not, it could be seeing an ABS wheel speed above the mph cutoff while the speedo driven from a gearbox sensor (before the diff) is showing you a lower speed. Strangely enough (3.73/3.55) * 135 = 142. If the Interwebs are wrong and the mph cutoff is actually 142, then if the ECU is not reprogrammed for the 3.55 gears and is using ABS wheel speed, it will cut off at an (uncorrected) indicated 135. Could be total coincidence.