Bruce,

I guess I called it a "Rex issue" because I think a lot of people don't consider that they can take the things apart and clean them. You're right though, the Bosch coils aren't at all immune to bad connections or internal faults. Believe me, I'm not one that needs to be convinced that it's OK to own a Rex-Regina car. I'm on my second one, a 92 745. We drove our 90 744 for 16 years - replaced the crank sensor one time and cleaned the coil once. That was it for ignition issues. On the fuel side of the house I think I replaced the RSR and FPR once each (certainly not Regina-only issues). I replaced the fuel pump once at ~150,000. Original O2 sensor still read good after 175,000+ miles. Personally I like not having to fear a failed mass air meter ($250 + ??), or maintaining two fuel pumps.

Interesting research on the coil grounding issues. Thanks for that. When I cleaned mine I cleaned everything included the chassis mount and all I knew is that it worked OK afterward. So not knowing what really fixed it, I've suggested cleaning the mount to people since then. Supported by your experiment, I think it's not a bad idea to clean the chassis mount just to provide some grounding redundancy in case the wire fails.

Take care...