'88 Civic hatch high/unsteady idle problem once warmed up...

I have an '88 Civic hatch, base model fuel injected 1.5L, 4 speed manual.

The idle on the car is usually fine and normal at maybe 750-800 rpm when I start it up for the first time in the day (I'm estimating, since it has no tach). After the the car has been driven 10-15 miles and is completely warm, it starts idling at ~1500 rpm. If I blip the throttle, it'll usually try to settle back into a normal idle, but instead it starts fluctuating monotonously between 800-1500 rpm, like a roller coaster, up and down, up and down, like its trying to find idle. Every once in a while I'll come to another stop and it'll be back to normal idle. The next stop, it'll probably be back to either high or fluctuating idle, etc.

Another occasional phenomenon that I think is related is that the car sometimes doesn't want to start, usually after its warm and running earlier in the day, or if I happen to stall out (only happened once, lol). It will crank and crank, and finally throw the Check Engine light. If I hold the throttle wide open, it will crank 8-10 times, then barely start up, and immediately begin the roller coaster style idle hunt fluctuating like I mentioned above.

To me, this sounds like an idle air control issue. In April I let my friend, who is an auto tech, borrow this car for about 6 weeks, and he mentioned that he adjusted the idle air screw, which I was annoyed to hear, as those are generally set from the factory. Anyway, I parked the Civic for the past 3 months, and this week I just started driving it again, and this idle/hot start issue bothers me. The hot start problem happened to my friend a couple of times, too, but he felt it was an ignition issue, which I disagree with.

Last night I tried to find the idle air screw he mentioned, and I don't see any such thing on this motor. In fact, I see no way to even adjust idle, and he doesn't remember having toyed with the idle, even though I distinctly remember him saying that's what he did.

All I see is a vaccuum actuated plate that looks almost like a secondary throttle plate. It is situated just above the throttle body.

Although I doubt it matters, the muffler fell off the car back in May, too, so I'm mufflerless. I thought back pressure loss from being mufflerless may also contribute to the car's difficulty w/idling, but I think there's something else going on.

Anyway, sorry to go on so long. It really seems like the car is getting too much air somehow, except that the problem only starts after driving several miles. Anybody know what's the problem?

Do I need to replace that little vaccuum actuated mechanical idle controller? Is there something electrical that could cause this (sensor, relay overheating, etc?).

Thanks!

Mark

Im having the same problem with my 88 civic dx 4dr 1.5l 5 spd. Have you been able to find out what the problem is yet?

make sure theres no air in your cooling system, because air bubbles will cause surging.

check all vacuum lines and gaskets for holes in them and that htey are all on good.

you can try and adjust your idle screw which actually fixed my surging

if that doesnt work spray the tb down with carb cleaner.

if that doesnt work, pull the plug on your iacv and if it stablizes yoru idle then do the next step.

if that doesnt work take off the iacv and clean it out by spraying it down with carb cleaner

im out of ideas after that

have you checked the lights on your ECU? I checked mine and i have 3 codes flashing. codes 3,5, 10.

have you checked the lights on your ECU? I checked mine and i have 3 codes flashing. codes 3,5, 10.

Yes. Every once in a while it doesn't want to start (when motor is warm), and it cranks until it throws the Check Engine Light...code 16, "Fuel Injector System"

It never had any of these problems until my friend borrowed the car, and adjusted the idle screw...where is that screw, anyway? It sounds like it may be the problem...its worth a try, anyway. I'd like to try adjusting it.

But that doesn't seem like it would affect or be affected by code 16... :confused:

i had an irratic idle problem, used some lucas fuel system cleaner, runs fine now

Try checking the main relay. It's a huge common problem with the 4th generation civics and leads to odd running habits and bad starting, sometimes won't even start. They were built poorly and so after all these years of bending and scretching due to the hot and cold weather, the circuit boards can't give a connection anymore. Try replacing that since it's usually the problem with anything regarding the fuel system.

Also, check you throttle cable. Is it too tight cause that will surely make your idle go up and down. Best way to check it is get it to where it will do the erractic idling again and put your foot under the gas pedal and lift upward. If it stops, then your throttle cable is too tight.

And I don't think your friend goofed up you idle either. As long as it idles around 700 to 1k rpms, then it's fine, no worries.

Hope this helps.

your fluctuating idle problem sounds like it might be cause by a "lazy" O2 sensor.

about the hard to start problem, check the injector harness connections and try to do a fuel injectors cleaning service (might be pricey).

first of all get rid of that crap ass d15 and either put a B16,B17,B18 in it!!pretty easy swap if you know what your doing