Possibly simply the oxygen sensor. But read through all the
following.

"cmcski" <skopinski@mchsi.com> wrote
> The car is reving high once the lights, blower motor, or
rear defroster is
> turned on. It will continue to rev high until those items
are turned off.
> If I turn on the A/C and the lights it will rev even
higher. It jumps from
> idle 750 to 2250 without the A/C with the A/C over 3000.
It does not stall
> out at all. I changed the plugs, cap and rotor when I
bought it.

You know the idle is supposed to be higher for every single
item you list being turned "on", right?

Not trying to be a wise-guy/gal. Just wanted to clear this
up.

So among other things, the question is whether this idle is
too high, and, sure, it sounds like it to me. For warm up,
the manual indicates your 87 Civic is supposed to fast idle
at 2300 to 3300 RPM. But should it be that high when you
turn on accessories like those you list above?

If this car landed in my lap, this is what I'd do:

Did you use genuine Honda parts, or aftermarket parts for
your recent maintenance? This is not trivial. Reports are
that non-OEM will affect performance. People seem to notice
this with just spark plugs!

Also, what about the ignition wires? Old ignition wires
frequently are the cause of rough running. Are yours OEM?
Have you checked their resistance? Should be under about 15k
ohms each. Tegger has listed some other checks you can do on
the wires. He also discusses general rough running problems.
The site is based on years of input and experience from this
group and his own explorations. See
http://www.tegger.com/hondafaq/start....html#symptoms

You should also thoroughly purge the cooling system of air,
per the manual's precise directions. The cooling system
cools certain engine control components. Air in the system
can mess up signals from sensors to the ECU, messing up the
idle signal.

Next, the manual directs that troubleshooting of the
carburetor is appropriate, especially the idle settings.
www.autozone.com has a complete manual for your 87 Civic.
There are two sections that explain how to adjust the idle
speed, in the tuneup section and the fuel system section
(under "carburetor," fast idle etc.)

Lastly, the problem may very well, and very simply, be the
oxygen sensor. Bad O2 sensors definitely can cause rough
running and crazy idling. I assume the mileage is a bit
sucky, too, right?

Has the O2 sensor ever been replaced on this car?

Genuine Honda oxygen sensors may be had extremely cheaply
(around $40 for your car) at
https://www.automedicsupply.com/ . I used them 18 months ago
for my 91 Fuel injected Civic. Good service. The sensor
works great. You can borrow, no charge, an O2 sensor wrench
from Autozone.

I don't know how people missed your first posts. Keep
checking back. I am not a caburetor kinda person, so I may
be missing something re the idle settings and adjustment.

Updates welcome, to help others in the future.