Thought I would check my ignition timing on the 1990 256 YJ. Checking at
700 rpm showed only about 3 degrees advanced. I advanced it to 9
degrees. I had to back the idle screw almost all the way out to get it
back to 700 rpm. The strange thing is that now after letting off the
gas, the idle is very rough and about 300-400 rpm higher. After a
varying amount of time 5 to 20 seconds, the idle drops to about 700 and
smooths out. When the idle smooths out and drops to where it should be,
there is a click somewhere on top of the engine. My guess is that it is
a solenoid. Anyone know what the computer might be doing after coming
back from high rpm to curb idle. It doesn't seem to be the sol-vac that
is doing it.

The good news is that the Jeep is way more responsive and has never run
better. If I could just get rid of the rough faster idle period I would
be a happy camper.

I have checked several times for a vacuum leak and so far no luck.

Also I am somewhat confused about the procedure for timing adjustment in
my Haynes book It says to disconnect the electrical connector from the
CEC sys switch located on top of the valve cover. What is this? It also
says to increase the idle speed to 1600 rpm and the the timing mark
should appear stationary. Does this mean that there should be no advance
between spec idle at 700 rpm and 1600 rpm? It seems there was some
advance on mine as you went to 1700 rpm, which I attributed to the a
centrifugal advance. When I checked and reset the timing, I only
disconnected the vac advance, but not the CEC system switch since I
could not find out what that was.

Guess I am missing something here.

Aloha from Maui
Joe