Ok sports fans, I've been workin on my 420SEL for a while now. I've overhauled the intake manifold and vacuum lines, switches and gaskets. The check engine light is still on. I've got some really strange readings, like no current at the EHA, easy starting but stalling when cold. I've got a X92 or X11/4 diagnostic connector with a push button but no LED and connectors at Pins 1, 6 and 7.
The idle speed goes up and down which indicates a vacuum leak. I didn't replace the rubber CIS air horn base because it looked OK. When I unplug the idle air valve, idle speed goes way up.
Here are some pics:
X11/4 or X92
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0026.jpg
Only pins 1, 6 and 7
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0027.jpg
Pin 1 Brown wire or ground
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0028.jpg
Pin 6 pink and pin 7 green
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0029.jpg
Pushbutton wires
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0030.jpg
Builder's plate
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0039-1.jpg
Air horn gap
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0042-1.jpg (while running)
No duty cycle
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0037-1.jpg (KOEO)
I suspect the ecu is shot
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0035-1.jpg
The idle valve works, I made sure it worked OK and was clean
http://i19.photobucket.com/albums/b177/wb300se/MB_420SEL/DSC_0031-1.jpg
There doesn't seem to be any voltage at either the CIS-E air flow pot despite it's position.
I think I need a similar 420SEL to use as a basis for testing.