Steve,

You inspired me to focus on the meter (or the way I used it) as the root of the problem and that was it. I was considering getting a used computer but hesitated since they probably rarely go bad and are often unneccessarily replaced.

My friend, a former MB shop forman lent me a home made device that he used on the early 80s cars. He recalled needing that devise set on 100. His more modern tester didn't work but his older devise (a black box cryptically labeled 100, 101R and Test) did. The unit's LCD displayed numbers that were reasonable and varied up or down as expected when adjusting the Lambda screw so i adjusted to 45. At higher revs (~2500) the Lambda stabilised within +/-5 the targeted 45.

On a side note i never could get either of my digital V-meters (don't have an analog) to vary from battery + voltage on pin 3 at idle and never got a 50, 70 or 85 reading on my friend's mysterious meter with KOEO. Maybe the lambda computer on cars such as an 83 380SL do not generate a "fingerprint" duty cycle with KOEO.

The new O2 sensor, a universal Bosch single-wire, splice-in part definetly made the difference for passing CA smog. Unlike the old sensor the new one moved above 0.9V with a squirt of propane into the throttle and below 0.1V with an induced air leak when disconnecting the booster hose.

Thanks for everyones help.

__________________
1972 450SL
1982 300D Turbo