Lately my Lg4 has developed issues at idle. It will idle at a low rpm and one time stalled. The M/C solenoid does the initial clicking when the key is in the On position for about 20 seconds then stops. But once I start the engine it starts clicking again, I don’t recall it doing that before. If I disconnect the solenoid the idle becomes normal. Does this mean it needs to be replaced?

 

That's normal, since its constantly adjusting the fuel mixture. Unplugging it while the engine is running should set a trouble code, so if it was malfunctioning already, you would of seen the CEL.

 

No codes. Guess I just never noticed it clicking after the engine started. By why would the idle improve by unplugging it?

 

Not sure, but i guess it runs somewhat on the rich side when you unplug the MC. You may need to adjust it mixture settings, but thats a more involved process.

 

If, as 84 1LE said, unplugging it makes it run richer, and as you said unplugging it makes it run better, the logical conclusion should be that something is causing it to run too lean. Before ya go turning any adjustments of any kind, your first order of business should be to check it very carefully for a vacuum leak, vacuum hoses and vacuum operated devices can and do suddenly malfunction, whereas the carb's adjustments really don't go changing by themselves all of a sudden .

PS, unplugging the MCS very well should have set a code and activated the CEL, so that's something else ya may want to look into as well

 

IIRC, the primary mixture needles are spring loaded and tapered. When the MC is off the needles unseat (due to the springs) being tapered the narrow tip is metering rich. The MC paddle is also loaded the same way, the paddle regulates the needles.

 

Thanks for the suggestions. I’ll start by hunting for vacuum leaks. Hopefully it’s something that simple