Civic idle variation

Hi,

When my 1990 civic (~180,000 miles, 1.5L, manual transmission) is
started in the cold, engine rpms tend to drop to almost stalling in few
seconds of running, then they recover to the usual "cold" 1,500 rpm
after few seconds. The idle rpms also occasionally drop to about 500 rpm
on the warm engine when I stop at a stop light and the engine seems to
hesitate for few seconds. My first step will most likely be to purchase
OEM wires/distributor cap and new spark plugs. All of those are
currently about 3-4 years old and the wires and the cap are aftermarket.
Would anyone care to comment on this and maybe suggest more
troubleshooting steps before I start spending money. I'd really like to
minimize the expense on fixing this problem.

Thanks a lot,

Alex.

 

Try thoroughly purging the cooling system of air. For this, follow the
manual's instructions to the letter. As part of this procedure, note that
it may take 40 minutes or more for the cooling fan to come on two times, so
have a magazine.

Something called the EACV (if I recall correctly) has a cooling passage in
it. If the system has air in it, it will affect the idle. EACV = electronic
air control valve or similar. It is the same as the idle control valve on
some Hondas, IIRC.

This was the problem I had with my 91 Civic (150k miles, 1.5L, manual) this
past summer. I went so far as to take apart the EACV. Air instead of
coolant was in its cooling line.

You might want to consider a new Oxygen sensor, too. Online the OEM part
runs around $45.

But I'd suspect the cooling system, first.

I think OEM wires are worth the extra bucks, by the way, and I'm a
cheapskate.