00 z28 timing trouble

[derek0122]

Ok so def need an expert on this one. Had my ls1 tuned, its a motor tune. (also had nitrous tune and done same thing ). The issue im having is when I accelerate hard to race my car drops timing. We had it at 23 degrees and it dropped to 10 degrees. You can force it with the laptop to hold the time but on its on it drops. What could cause this. Thanks in advance for any help or suggestions.