Hi All,
I'm trying to understand the operation of the Oxygen Sensor and ECU combination better. I'm aware of the contrary position that MB takes wrt 'duty cycle', still .... say: the engine is running lean (direct Oxygen Sensor volts is below 0.5V) and the lambda ratio (pin 3 on X11) shows large duty cycle (ie voltage spends most time at 0V and only 1 or 2 mS at 13.6V ... the battery voltage). This suggests to me (probably wrongly) that The ECU at 0V is somehow causing an increase in the fuel flow? Is this done via the EHA valve? What, exactly, is controlled by the lambda ratio.... ie when the ECU is at 0V and/or 13.6V. Could it possibly be the idle control valve (ICV)?
The above numbers are in fact for my '89 300E. I'm guessing that the O2 sensor is working but that somehow the gas/air mixture is not being enriched. The idle is poor and the car easily stalls when coming to a stop. Disconnecting the O2 sensor fixes the stalling of course but is likely not good for fuel consumption and the environment.

would appreciate any insight

cheers, guenter

I want to say you have a Bosch KE-Jetronic system. Do a search on Google for exactly that you will find a wealth of information. More then you will find on the forums. These are very complicated injection systems that not may people know how to really work on.

__________________
Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

..... indeed, found lot's of information! Compliated all right, but it makes more and more sense as one works through it slowly.

Many thanks.