Some 1975 models have idle solenoids. Due to the leaner carburetor settings required for emission control, the engine may have a tendency to "diesel" or "run-on" after the ignition is turned OFF. The carburetor solenoid, energized when the ignition is ON, maintains the normal idle speed. When the ignition is turned OFF, the solenoid is de-energized and permits the throttle valves to fully close, thus preventing run-on. For adjustment of carburetors with idle solenoids see the section on carburetor adjustments later in this section.