w124 koeo is 90%, not 70% or 85%, meaning what?

[richard28]

On my 87 300e, built in October 1986, I'm trying to eliminate off the line sluggishness first by leaning the mixture. So, using my Sears digital multimeter, with key on engine off, the reading at pins 2 and 3 on the diagnostic socket near the left fender is 90.5% (there is no pulse counter socket near the battery). According to the manual, with the engine on and warm this would mean a bad EHA if the engine was warm, but would that apply before the car is even started? When the car is on, the duty cycle stays unchanged at 90.5, and I was going to swap the EHA for a known good one to see if anything changed. I'm also planning on calculating duty cycle using the voltage test to see what that produces. Is the % duty cycle supposed to work on a car that old? Any thoughts? Thanks.

[richard28]

In researching this forum, i found a post by Zorin, who said that for a 103 engine a 90% duty cycle reading means the duty cycle is nonfunctional, without fault. So this weekend I made adjustments based on the voltage from the oxygen sensor. When the fluctuating readings were approximately .5volts, I stopped, and then took if for a test drive. The sluggishness from a dead stop had disappeared, pickup was good and the idle was pretty smooth, minimal shaking, but was reading lower than before, less than 500 rpm if the tach is correct. I then was going to swap the EHA with my parts car, but I noticed I need a t-20 socket to remove the two screws (the parts car, a 1988, used regular screws). Seems like MB made EHA removal unnecessarily time-consuming. To be continued...