Steve, I don't know what happened yesterday, I repeated the measurements a couple of times and always had the same results. Today however, I got U12=1.3V at idle and was able to reduce it to .65-.75V. Either I repeated the mistake or the ECU or the multimeter acted different this time.
This pushed idle stability a bit forward to this silkiness that pursue, but still left enough space for improvement.
The idle air valve received 665mA, MB ref is 600+-50. Do you see a problem here?
Unfortunately I didn't read enough about the EHA current before I measured it today
I did not look for the polarization...
First, at idle, I read a stable .7mA. After a short gaz kick and return to idle the current fluctuated between .7 and 7mA (maybe -.7 to -7mA). The idle didn't feel less stable after the kick than before. At 2000rpm it was between 3 and 8.5mA.
Since I have the same rough idle with a cold and a warm engine but a smooth idle with EHA off, I would not focus on the idle valve unless you say, 665 mA is too much. Unfortunately I don't have a duty cycle meter nor can I find my rpm meter (lent?). I intend to check the following next:
-EHA current eng off ign on 20mA to check the OVP relay
-injection cone and throughput of the valves
-0.8mm spacing of sparks (resistance of wiring has been checked already)
Are you aware of anything else I could check without the duty cycle meter that makes sense?