Serious Rough Idle and stalling on 89 Civic

89 civic with 200K miles on it. I'm having a very serious rough idle
and stalling problem
lately for past 2 weeks. Previously I did had a little rough idle
problme during warm-up and
I ignored it as the car warmed up the rough idle is gone. Now in past
2 weeks, it got
worse. I thought it has to do with cold weather. During warm-up the
rough idle is so bad that the RPM needle is moving up and down crazy
and I've never had this terrible idle problem before. Not only that,
the car is stalling when I stop at red signal. Never had
that before although the car has never shut off. One thing I do know
is that the car does not stall when I push the gas. Why is that
stalling at idle? Is fuel filter is about to go? Shall I replace
rotor or igntion coil? O2 sensor? PCV valve? Other?

 

Possibly a worn out distributer shaft. I had a 92 Civic that idle rough
and stalled. Took it in and the guy diagnosed it to worn out
distributer shaft. I had the distributer replaced and the problem went
away.

A worn distributer shaft could cause the rough idle and stalling as the
timing is not steady and varies all over the place.

A way to check for distributer shaft, is open the distributer cap, and
see if you can shake the shaft, ie does it rattle? Also connect a
timing light and see if the timing is steady.

 

Here's what I would do, in order, based on my experience and
some reading here:

Properly purge the cooling system of air. Use the manual's
directions. www.autozone.com has a free online repair guide
for your car. Remember, it will likely take at least 40
minutes for the fan to come on twice. The coolant has to get
as hot as possible, so as much air as possible is released
during the procedure. The cooling system cools not only the
engine but certain engine sensors which will affect RPM. In
particular, the cooling lines to the EAC valve are a high
spot where air can accumulate. This valve directly affects
the idle.

Ensure the ignition wires and plugs are genuine Honda or the
ones Honda specifically recommends. NGK plugs seem to be the
preferred ones. Prior to replacing the ignition wires, run
the car and with an air mist sprayer, spray them down
thoroughly with water. If the idle changes, definitely
replace them. See www.tegger.com/hondafaq 's section on
running problems for elaboration on this.

I am doubtful the air and fuel filters are the problem, but
I would still replace them, and at least clean and check the
PCV valve (with WD-40 or PB Blaster) as well. If it's the
original PCV valve, I would consider replacing it with a
new, genuine Honda one. Replacing these last three things
(air filter, fuel filter, PCV valve) will minimize
interference with your efforts. Besides, they are all
routine maintenance items that have to be changed every so
often, anyway. Total cost should be under $75.

The distributor cap and rotor should be genunine Honda and
not too old, also.

Check and adjust as necessary the idle speed. See the manual
for how to do this. Check and adjust as necessary the
ignition timing.

I would not suspect the oxygen sensor or coil at this point.
An old O2 sensor can be a problem /after/ warmup. An old
ignition coil also tends not to be a problem until after
warmup, as well.

On the other hand, replacing your O2 sensor pre-emptively is
not a bad idea at this point. Aged O2 sensors do affect
performance in general. The place from whom I bought my 91
Civic's new, genuine Honda oxygen sensor had very low prices
for them. I don't know if they ship outside the U.S., but
for price comparison purposes, see them at
https://www.automedicsupply.com/ . A sensor for your car
from these folks should be under $50.

Updates are welcome, to help someone else in the future.

 

Thanks for input but I'm looking for a specific part that is direct
causing
the problem.

 

Do tell.

Ever notice how manuals have "troubleshooting procedures"?
For example, a certain troubleshooting procedure will list a
number of symptoms, and the steps have the technician (or
amateur do-it-yourselfer) investigating a number of possible
causes.

But please give this tip of yours to all local mechanics and
physicians. I too am tired of them not being able to
diagnose a problem, and then fix it, the first time I
present it. They mess around trying different things, and
after an hour, some still haven't diagnosed the problem. Or
worse, they'll insist (in true macho style) they have fixed
the problem, and I'll be back within two weeks, with the
problem still present.

Anyway, I don't want to push you around. The School of Hard
Knocks is superior to any old person sharing their
experience. ;-)

 

Yeah I unassembled rotor and cap and cleaned the metal part bit of
decomposed area with
sand paper and I replaced PCV valve. The rough idle seemed to bit
disappered. I will try to
replace fuel filter next and see what happens.

 

Did you shake the distributor shaft to see if it was loose? Did you
connect a timing light to see if the timing was steady? Also do you
hear ticking noise from engine? This is usually a sign that the valves
need adjusting. All of these troubleshooting steps do not cost any
money and do not require replacement of parts.

 

If the ticking goes away after warmup, perhaps a check is
appropriate, but an adjustment may not be. The valve lash
may simply be set at the high end of the spec, which is less
risky than it being at the low end.