As I've been doing a little research on retarding my timing in order to improve emissions, I stumbled upon this thread and find it interesting that the shorted plug condition retards timing by almost 1/2 at 1500RPMs.

But what's more astounding is that the open circuit condition, that I've read many rave review about, seems to have virtually no impact on timing advancement, and therefore engine performance. This is quite a discrepancy. What could be the explanation for this?

__________________
Steven
1989 260E (276K miles)
1995 E320 (50K miles)