idle hunts only when cold
 

hi.
i have a 92 190e 2.3.
new problem started last week out of the blue. first thing when cold and only when cold the idle will hunt badly, it goes to about 1200 rpms down to almost dieing and back up and back down over and over untill after a few mins and once its warmed up it idles fine (not perfect but ok). after that it runs normal upon restarting. i cleaned icv, checked ovp fuse (no lights are on), cleaned throttle postion switch. been looking at past threads alot lately and cant quite figure that problem out. any guesses what i should try? thanks batman

clean your air intake temperature sensor, i know it sound crazy, but two guys on benz-world have reported weird cold idal problems (on 320's but exact same issues)that completely disappeared when they cleaned the intake temp sensor.

forgot to mention that i tried that also. took it out and sprayed it with carb cleaner, no effect.
keep em coming. thanks

update...
 

last night i was feeling it and opened up opv relay and reflowed all the solder joints, and while i was in the area i did the same to the fuel pump relay. i took out the temp sensor which is only about 25,000 miles old as is the 02 sensor. i replaced spark plugs which helped it run better after it was warm. still stalls when cold. any more ideas? thanks

A cold engine requires a richer than normal mixture and a little extra throttle to compensate.

Components involved are
temp sensor
cold start injector
idle control valve

Vacuum leaks defeat the purpose.

Start spraying carb cleaner around, you'll find the vacuum leak.