When did Lambda ( O2 sensor ) start?
 

specifically in the 280E series? Would a 79 have it?

I'm not sure, but I think that one had the mechanical FI. The Lambda sensor came about when the "electrified" the K to make it the KE. See the disclaimer below though.

On USA versions 1980, 450's & 280's

IIRC the K-lambda system was used nationwide on the 1980 models, might have been as early as 1979 on California-bound cars, but I would have to check that out. The main identifying feature of that system is what Bosch called the frequency valve which looks like an electronic fuel injector in the control pressure circuit of the fuel distributor. This is not the same as the KE-Jetronic system used starting 1986 with the EHA mounted to the fuel distributor.

For you guys who have worked on these... which do you find easier to get working correctly, K-jet plain vanilla or K-jet lambda? I am in the market for a R107 for SWMBO and simplicity is a concern...

Rick

Have seen several R107's with OM 617 turbo diesel engines.
That is the best of both worlds!

The thought has crossed my mind as I have a spare OM617 and there's a "roller" R107 locally...but my wife says I don't need another project car, especially one that she wants to drive before one of us dies.

thanks guys!