Ok my 93 rx7 had a problem with idling. I would idle at 1800 rpms and bounce to 2100. Then at night the rpms would rev higher when I turned my headlights on.

So I was checking all my fluids and I noticed my coolant was low. So I filled it up and I left it run for 10 min then went to bed. I woke up this morning and started my car and my idle went to normal! It now idles at 700. I'm shocked.

Can anyone explain what happened?

 

My guess is the Thermowax was not getting coolant, so it was not pushing the piston out to kick the idle down.

 

Hmmm. Ok well thanks for shedding some light on it for me. I'm just happy is fixed.