What causes negative spark timing

[AL]

Thanks for the info Bob, I appreciate it, Im glad I am seeing this as normal operation

[douellette]

my 97 cutlass says the same exact thing when i scan it so i was also wondering if that was normal.

[BXX]

Yup, perfectly normal..

 

Jut remember, when it says -30* at idle like yall were saying, its not really 30* positive. Idle timing is around the 18* mark

 

I have to make the PID modifier in my HPT setups scanner so I can datalog timing correctly.

 

I was kinda startled when I first hooked it up and saw negitive timing!! Then I read the 'help' in the HPT Suite