according to my friendly local smog check guy, 88-91 civics no longer
need to have "california" emissions equipment to pass california smog
testing - all they have to do now is pass the federal standards that
were in force at the time.  [can anyone confirm this?]

this apparently means that you can disable the pesky egr system, or even
get rid of it since it's no longer required to be present - a big
benefit since the egr system is hugely unreliable.  [on this age civic,
honda evidently didn't anticipate the very low quality gas we have since
federal detergency standards were decreased, and they welded the inlet
manifold back up after drilling the egr ports.  [these days, the egr
ports are blanked with a removable plug.]  the only way i can see to
clean the port is to drill the welded section back open - a giant pain
to re-close.]

getting back to the egr, to make the game a little more interesting, you
can't just disconnect the egr system from a california vehicle without
tripping a code on the ecu, so the easiest thing to do is simply get an
out-of-state ecu that doesn't look for the egr or operate it if present.
 instantly, you then have a vehicle that runs much better, shifts more
smoothly, and maybe even gives better gas mileage [although i haven't
tested that bit yet].  i know the first two bits because i scored a
non-ca ecu at a junk yard today [$35], and have been driving it.  all
the usual egr activity has gone and no code trips when the egr is
disconnected.

interestingly, the new ecu also immediately set a code for my lockup
solenoid that had been causing some concern, so i swapped that out too,
the code disappeared and lockup is completely back to normal.  i'm not
sure why there would be no code with my old ecu - maybe there was some
funky degradation in the output transistor.  it was doubly confusing
because regardless of the ecu, the solenoid appeared to test ok, but it
just wouldn't work right.  anyway, all is now back to normal and life
without egr is great.

ps. it's useful to have a backup ecu just in case of weird diagnostics.
 it's extremely unusual for one to actually malfunction, but it seems i
have one that has, partially at least.  current pricing being what it is
for this older generation ecu, a spare is a handy, affordable tool.