Early W116 V8s used Bosch D-Jetronic while later cars (and the 6.9) moved to K-Jetronic/CIS. Some owners, especially from the diesel side, say to avoid D-Jetronic 'like the plague' over complexity and parts, while CIS is defended as robust and 'not voodoo,' with a poorly-running CIS car seen as an easy fix that sellers leave money on the table by not sorting.
Fuel injection: D-Jetronic versus K-Jetronic/CIS
Mercedes-Benz S-Class (W116) · mechanical