Trying to sort out a little issue for a friend of mine... '87 Civic, auto, D13A1 engine with Keihin 2bbl and manual choke... it's recently started idling too high, and seems to get higher as the car warms up. She can start it cold without even needing to engage the choke.
I've checked all the cables and linkages, all seem to working properly, nothing sticking. Idle screw is backed out all the way. Primary butterfly appears to be fully closed, yet the idle (if you can call it that) just keeps speeding up.
Only thing I can think of is an internal leak in the carb; there does seem to be some gas leaking down the outside of the carb on the side opposite the float bowl as well, and the hat screws were, if not really loose, then not really down tight... but even then, the butterfly looks fully closed and it's running as if the thing is halfway open.