Does retarding -.5 deg on the timing table takes out -.5 deg of spark advance or -1 deg of spark advance?

 

I am not sure what you are asking, if you put -0.5 in a cell, it ECU will run the ECU's preferred timing - 0.5 degree. That means if your ECU wants to run 16 deg, XEDE will modify the signal and have run it at 15.5 deg.

Hope it helps.

 

Thanks, that was along the lines I was asking. Someone told me it was double the value you entered in the cell. If you entered -.5 the actual change was -1.

 

no other poster is right