Limp Home Mode

[MercedesTech]

:sniffle:

Was playing with customizing my tunes yesterday after work (stock tunes, waiting for Bill's custom tunes). I was using #3 performance tune. I changed tire size to try and dial in my speedo, I adjusted WOT shifting, but not by much. I am around 5100 on the 1-2 shift and a little less on the 2-3 shift. I then bumped up my timing to "1". I programmed it, went to drive off to see how it feels. Made it 100 yards with no issue. Then "pop" and instant loss of power. Engine stayed running, the wrench came on, and I was in "limp home mode". I then stopped, went back into the gryphon and reset previous (befre these changes) settings. Loaded those and was good to go.

What I'd like to know, was it my timing bump ? How much does each .25 actually advance the timing ? What would be a safe timing bump ? if any.
My truck is a 2004 Ford F150 4x4 w/ 4.6 L motor. I have a Fabtech 6" lift, 35" M/T tires. No other real drivetrain mods. I only run Chevron 91 octane (highest octane out this way).

Thanks for any info.