I have had this problem with idle and starting for a while now, it's not critical, just a bit annoying. I'm especially suspecting the engine don't get the proper values for warm-up enrichment from the coolant sensor.

I have read many posts on this great forum about monitor the values sent to the EHA, but I'm still unsure how to hook up the multimeter.

Will I need additional wires? If I pull out the connector, will I still se the same values? Must the engine be running, or do the ignition just have to be turned on for the warm-up enrichment?

What values should show up depending on coolant temperature?

By the way, the car is a 85 Euro 190E 2.0

Euro cars can be different
 

Unless your Euro car has a factory installed O2 sensor the values are different than the US cars. MOST important items are current flow when cold, & basic fuel pressures. To measure current flow you need a multi-meter with mili-amp range, & a jumper wire.