Disconnected Idle Control Valve
 

Good morning to all!

OK...well I've been struggling with a idle surge and occasional stall on my 1991 300E for the last 2 months which has gotten dangerous with Fritz wanting to mate with the car in front of him at red lights.
I've checked for vacuum leaks (none); I replaced the OVP with a new dealer part (no difference); Pulled out and cleaned and lubed my Idle control valve with carb cleaner and WD40 (helped for a day); changed out the idle control valve with one from a pick and pull (stopped the problem for 2 days and then it returned); replaced the hoses on the ICV (PITA); changed coolent temp sensor (no difference); and lubed all throttle linkages.
3 days ago I decided to disconnect the electrical connection on the ICV and havn't had a problem since. It idles at approx. 750 RPM; starts right up with one crank on a 35 degree morning; and runs beautifully.

Are there any long term ramifications of driving around with a disconnected Idle Control Valve?

Nick

Have you ever changed out those pesky idle air hoses? ps2cho has a very nifty DIY/trick to do them on his website. I changed mine out and cured all of those issues.

Yeah, I changed them using his trick. No change in the surge

Wow. Amazing that you are having good perf with unit disconnected. Maybe it leaves it in an open, closed, or halfway position. You said you substituted with a junkyard one and had same issue. Was this with the replaced hoses or before? Have you tested your valve with a separate power source to see if it clicks and works? I did with mine and that is when I saw the splits/cracks in my hoses.

Also check the decel microswitch in the linkages. It's the grey switch with the roller that contacts the linkages. If that's your culprit you may be able to reconnect and have idle control again.

No problem if normal use- it's just air.