Im troubleshooting my elr and here is what is happening so far:

Car is an 86 300sdl, with the om603. When I move the elr position from 1-7 the idle speed does change slightly, but not enough. Then, when I disconnect the plug from the back of the IP the idle drops as it should, and when I connect it again it raises and the elr behaves as it should, with positions 1-7 having a noticeable change in idle speed. Then if I turn off the car and restart it, it goes back to a lower idle again with positions 1-7 not having as much of an effect. Any ideas what part of the system may be causing this?

Service manual here:

http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/07.1-1120.pdf

The procedure for your engine starts on page 22.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech