87 Civic 4 door

I just purchased this car it has 212K. I replaced the ignition cap and
rotor, spark plugs, fuel filters and changed the engine oil. It seems to
run a bit rough, it hunts at idle slightly.

The real problem is when I turn on the headlights, the idle jumps from
about 750 to about 2250.

I have not found any vacuum leaks (doesn't mean there isn't one)

Anyone have any idea why and how to correct the idle situation.
Thanks

 

Forgot to mention the specs
Engine 1.5L Carburated
Trans 5 speed manual

Again thanks

 

Has anyone experienced this problem?

 

Can you describe the exact nature of the problem? Does the
car rev high or low at stoplights? Tend to almost stall at
stoplights? What?

 

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.
Thanks

 

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

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/startproblems.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.

 

I did use the NGK spark plugs, the cap and rotor are GP Sorenson. I did not
change the plug wires. I will check them though.

The O2 sensor may or may not have been changed I will pick up a new one
since i do not know.

I did not realize that the idle would increase by turning on the
accessories. The guy I bought the car from never experienced this. The car
did sit in his backyard for over a year though.

Thanks for the web site. I will head on over to the zone and pick up a
manual.

 

212k miles... if the O2 sensor is the original, this is a
good investment.

experienced this.

IIRC from some discussion here recently about this
(reinforced by some comments in the manual), for my fuel
injected 91 Civic, the computer does this to assist the
alternator, now under higher load from the electrical
accessories. When I turn on the headlights or defroster,
say, I see increases of only around 250 rpm, though. So on
my 91 Civic, it's quite noticeable, but not as stunning as
the revving you're seeing.

Hopefully that will draw other comments. The net has sites
that talk about how to maintain a car after it's been
sitting that long. Might want to google.

I hope you noticed the manual is /free/ online.

 

does it still use a solenoid to boost the idle? could just need a little
turning "down" with all the loads at work.

 

Thanks
I will check to see if that is the case. I did not see one but there are
alot of vacum hoses around the carb.

 

For fuel injected engines, my manual mentions an "A/C [as in
air conditioning] idle control solenoid valve." I don't see
anything similar for carbureted engines.

For the carbureted 87, by way of what to put one's hands on
during the two idle adjusment procedures and when using the
troubleshooting chart, my manual lists:
(1) a "throttle stop screw" (there's a drawing of where this
is);
(2) a "fast idle adjusting screw" (also shows a drawing of
where this is);
(3) a "stuck air bypass valve" (troubleshooting section).
(4) a "stuck open throttle valve" [So try cleaning the
carburetor?]

Again, I'm not a carburetor person. I'm just copying from
the manual here, trying to learn more. I defer to your hands
on and book experience, Mike, of course.

 

Okay,
I located two vacuum leaks on the back of the carb, put new hoses on and
readjusted the idle screw. That seems to have fixed the problem. I still
need to change the O2 sensor.

I lubricated all the linkages and springs.

Once I drive to work and then back home I will see if I need to tweak it
anymore.

I do appreciate the help and web sites.

 

i havent touched a carb in years. thank ghod for that! i just remember
GM using a solenoid setup like that, tho id expect better from honda