Interesting,
This isn't the easiest reading, but explains the difference in two seperate distributor/advance systems available in the mid 90's,
ESA and
VAST. It also discusses the DLI or "distributorless" system that came about in the later 90's. If I'm not mistaken, in a nutshell, the VAST system assumes cam position info. directly from the distributor location and self times. The ESA system uses a sensor to find cam position and requires "base" timing being set at 10 degrees and works advance from that point. Enjoy??
fixed link
Chris