15.6V@WOT normal?
I am also wondering if this voltage is taxing my HP. If so; is there a way to make changes by using HP tuners?
ground?" - PCM ground might or might not be the same
voltage as block ground (should be; assume nothing),
which is what the alternator refers its output to for
regulation. That wants checking.
The first thing to check is the battery,a bad one can cause
a high charging voltage and testing the alternator on the car
is not a valid test w\o a known good battery. One thing for
sure is the battery won't live long at 15+ volts.
Guess I will be checking for lose/bad grounds.
The good: Might have found a few more HP

