And what is the EHA amperage doing (mA)? It is correct at 8 mA mid range

Lambda (Duty Cycle %)? It is correct - 70% idle, goes to lean as it should with O2 disconnected (open loop). With O2 connected when it switches to closed loop it stalls. See my description above.

[With oxygen sensor connected / disconnected?] *

Is that a heated Oxygen Sensor with separate wires for the heated portion? Yes....2 white wires for heater, 1 black for signal.

* The car should still run with the oxygen sensor disconnected. Or with other CIS-E sensors not functioning/wires shorted/disconnected - Called "Limp Home Mode". The computer replaces the "improbable value" with a midline value which should allow the vehicle to still operate. More and more of these features were added to later model cars. I don't know which years had which limp home features? (Or if earlier years had no such features on the CIS-E computer or not?) It appears that the negative sensor readings will not allow the limp home to operate. It runs in open loop until heat up but after switch to closed loop it loses control and will stall. If I disconnect the wires to the EHA the car will now do the limp home. Like I state this strange negative response from the sensor kills the limp home capability and this surprises me. I will know the picture when I change to a new sensor.

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Dionysius