Many factory cars have a charcoal canister which stores the fuel vapour coming from the fuel tank. A purge solenoid allows the charcoal canister contents to be vented into the engine during light load.

There are no settings to adjust as other than selecting the output controlling the solenoid.

 

The purge function will turn on the purge solenoid when the following three conditions are met:

 

Therefore the engine must be warmed up and operating in vacuum, but not at idle.