The evil lamda control
My '91 300SE exhibits lean condition on warm startup.
It chugs and struggles for a couple of seconds, then smooths out and runs fine.
-I checked the EHA current - approx 7ma at idle.
-I checked terminal 3 on the round connector with a voltmeter (my old dwellmeter died). Approx 3 volts, which indicates approx 75% duty cycle - it's adding fuel, correct?
So... it seems I am indeed a bit lean on the base setting.
But the 02 sensor is correcting when it comes online.
I assume it's time, after 13 years, to adjust the Lamda screw a bit. The motor runs great, but has exhibited this warm-start stumble for about 12 years - so maybe it was always set lean?
Does my analysis seem valid?
should I look for another problem before I jump on the Lamda screw?