FINALLY!

Took the 300E to Starbuck's this morning, with the DMM still hooked to the EHA test harness. Stopped at a light, just about after the engine reached operating temperature and felt the stumble. Drove it about a half-mile, running badly under 2000 RPM. Reached parking lot and allowed it to die, and restarted a couple of times.

The change in the EHA current readings was that during the episode, they went to -2 to -4 mA, generally staying around -3. Normally at idle and driving, they have fluctuated closely around 0.

My interpretation is that the coolant sensor could be bad, and is telling the control unit to richen the mix, and the oxygen sensor is picking up the richened mix and the EHA to try to lean it.

Other thoughts welcome!

TIA

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe