On "other" cars from the same era (dare I say "foreign"), the solenoid is called idle shut off solenoid. Sole purpose being to prevent *any* fuel being drawn in the engine after shutdown, so it wouldn't self ignite after a hard run in the hot combustion chamber. On old american iron, I don't know for sure. What is the purpose of having two idle speeds?
I did check in my old Chilton book and it has a short section on adjusting my '70 230/250. It mentions setting high idle first to 600rpm and finish off with solenoid wire disconnect to set the idle to 400rpm.
Heck I might as well quote the whole section:
With air cleaner in place and engine fully warmed up, "fuel tank" line disconnected from the vapor canister (EEC). Distributor vacuum line disconnected.
a. turn in the mixture screw until it gently seats, then back out the screw FOUR turns.
b. Adjust the solenoid screw to obtain 830rpm for manual transmissions (in neutral) or 630rpm for automatics (In Drive).
c. Adjust the mixture screw to obtain 750rpm for manual transmission (In neutral) or 600rpm for automatics (in Drive).
d. Disconnect the solenoid wire and set the idle speed to 400rpm, then reconnect the wire.
e. reconnect the distributor vacuum line.
I have no vapor canister, thus no fuel tank line to disconnect from it.
Glad I checked, now I know. Still, I can't see why I need two idle speeds and potential dieseling. I use the solenoid to prevent dieseling as I explained above. Yes it won't start or idle unless I tap on the gas pedal once after ignition is turned on. The solenoid is not strong enough to open the throttle from closed position when energized.
