Fast Idle Valve Disabled?
 

My Civic '95 ESi (1.6L SOHC non-vtec D16 variant), had a high-idle
problem before. When warm, there was suction at the TB lower port
(which according to the manual, there shouldn't be). I temporarily
"fixed" the problem by blocking off the fast idle valve.

When started cold, the EACV seems to be effectively taking over the
role of the FITV, raising idle accordingly. Is this a workable
solution? Any ill effects from this?

We don't get winters here, so very-cold-start is not an issue. In fact,
on later Civic models the FITV is missing; there is only one TB port,
and the IACV (EACV) takes over everything.