W126 low ICV voltage
 

My '91 300se has developed sluggish idle fluctuations. When you put it in gear the idle drops low then corrects itself. I checked the ICV and it works fine. However, I'm getting only a constant 2.5V to the ICV. The wiring diagrams show a different arrangement for the OVP for this model year. Does anyone know if the OVP would be suspect in this case ? Any suggestions ?

The fluctuating idle may very well be related to the ICV. I would at the very least clean it and replace time-hardened hoses. Look for other vacuum leaks as well.

There's a very recent thread by "RonInSC" regarding the ICV. Here's a pointer to it:

http://www.peachparts.com/shopforum/tech-help/157171-idle-control-valve-hoses-changed-300-te.html

The OVP gets blamed for everything imaginable. In my case I was dealing with the following situation:

After a lengthy drive(enough to get it good and warm), I'd pull over to do business somewhere and come back in 10-15 mins. Start car and drive off, but not for long. Car would die. Put it in park and restart. Most often the vehicle would restart and drive if I got back on the road and kept it at speed. If I came to another stop shortly after the restart, car would often times die again.

Replaced original single-fused OVP with revised dual-fused model. Problem solved.

Mike, thanks for the info. I've already replaced the hoses and cleaned it. I get proper operation of the ICV when connected to battery. However, the connector to the ICV is only providing 2.5v KOEO. The manual states 12v. Also, when I disconnect the connector there is no change in engine speed. Other threads have pointed to the OVP but the wiring diagram for this model year shows the ICV wired to the CIS-E control unit, not the OVP. So, maybe there is a still a connection but it's not clear. At any rate it's a nuissance. Other than that the car runs like a champ.

Consider what Steve Brotherton had to say in this thread.

http://www.peachparts.com/shopforum/tech-help/44442-car-stalls.html?highlight=ovp+powered