I have been diagnosing the air-fuel system on a 190 E 2.3 with KE ll Engine #102.985. Engine would not start. With the help of this forum I was able to check, test many components. Found OVP relay coil was bad. Contacts would not pull in. Still no start. Replaced cap, rotor, plugs. Rotor was burned up,cracked. Engine fired up OK but idle is rough. With vacuum gage connected to barbed fitting at lower intake manifold, needle on gage pulsates from 9 to 13" Hg. When connected to either of the 2 fittings on side of throttle body, vacuum reads 0. If I open throttle plate to 25%, RPM's go up and vacuum only goes up to 5" Hg.
I suspect a vacuum leak and have checked all around the IACV hoses and rubber boot above throttle body. Checked with mirror and small light under intake plenum. Also checked with flexible viewer scope at every place I could. No visible cracks or splits. I do not hear any hissing sound that a vacuum leak would make. Even tried propane through tubing placed at side of throttle body. RPM's went up only once. Couldn't get it to do it again with the propane. I didn't want to leave the valve open more than 10 seconds.
I need to find out:
1. What should vacuum at throttle body be at idle.
2. If IACV does not close off tight, will it lower the throttle body vacuum?
3. What should vacuum be at intake manifold. I thought is was 17 to 22" Hg.
4. What is the normal position of 3 pin IACV unplugged? Spring return?
I have searching the forums for days and haven't been able to find info.
Any information or ideas would be a great help.