I'm having a problem with my initial spark advance, the truck runs great with the tune I have now, but with the initial spark advance set at the stock 0*, my motor however runs best with the disty turned to 8*. When I go in and change the initial spark advance to 8* it runs horrible, it's so bad its un-driveable, has no power and pops out the intake with anything over 25% throttle. That was the ONLY thing I changed between tunes and when I went back to 0* on the chip it was fine. Whats wrong?

 

I suggest that you hit the Tuning Guide book sticky (up top), chapter 5, '8063/'8746/'7747 ECM, then the SA logic thread. That will explain what the changes you have been making do to the SA.

RBob.