On my 300SDL there is a little black unit with a dial and numbers on it on the driver side in the engine compartment, just behind the fuse box. It has numbers on it from 1 to 8 (I believe) and can be adjusted by pulling up and rotating it. Does anybody know what this is and what the adjustments do?

__________________
Mahalo and Aloha,
S. L. "Red" Pike, Naval Architect/Marine Engineer, USCG Licensed Chief Engineer (Steam, Motor, and Gas Turbine)
Former nuc bubblehead (boomers)
"Sustained superior performance through continuous incremental improvement."

1987 300SDL White w/ Gray Leather interior, 160K (mine)
2009 Nissan Murano (leased - wife's)

Of course we do. We know everything.

That dial is your idle adjustment. There are six?? positions and each position will move the idle upwards or downwards by about 40 rpm or so.

This engine has a computer controlled idle so that it maintains idle speed no matter what the engine load (a/c or electrical).