Alright I have had the problem for a month or two now, and so far I've cleaned out the TB, AICV, and the FITV, and also maybe unrelated, I had a shop do a fuel system cleaning. I've also tried bleeding out the air from the system, but it's kind of difficult to do with the coolant going up and down, and with having a 95 civic I have the bleeder screw, but it's broken off twice(Replaced water outlet twice) so I was done using that hahaha, and just did it with the rad cap.

I should also mention that this started happening after I let the gas get a little below 1/4 of a tank. When I first go the car, sometime this summer, so about 4 months ago, I did a tune up including Fuel filter, air filiter, plugs&wire, and distributer cap.

This might be contributing to the problem, but I'm not sure. My car, whever it is a little warm outside (50F+) it begins to overheat at highway speeds, so I'm thinking the radiator is clogged/may have more air in it, because the fan kicks on, and the thermostat and thermostat sensor are new, along with a new rad cap. But if it's cold outside the car runs fine and will never overheat. Anyway...I heard having clogged radiator, or air in coolant system causes a surging idle. But the overheating thing came before the surging idle, not really at the same time.

So please someone have an answer for me! Haha, I'm going crazy over this stupid idle problem. Thanks everyone!
Car is a 95 Honda Civic DX completely stock

 

Bump

 

Try this:

Bleeding the cooling system may take 20-30 minutes.

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push/turn the dash heater lever/**** to MAX heat. Fan need not be on.

3) Follow the directions in the diagram below

 

i had a horrible surging idle for about 2 months, then one day at my buddys shop i decided to get my ecu chipped (93 coupe with mini me swap) and it stopped, lol, weird

 

@Ron-Well I already tried doing this, but the coolant inside goes up and down and some bubbles come just from it doing this because it falls below the little spout(?) that the cap goes into. So I'm not too sure when to stop, but I think I got alot of air out as I did it for about an hour.
I'm going to have the radiator flushed because my poor college @$$ will be finally running into some money, haha but that should get rid of all the air if there is any correct?

and @Krogers-LUCKY YOU!!! Hahaha

 

Anymore suggestions??

 

Just a quick update....

I plugged the whole to the IACV inside the TB and nothing changed. I sprayed some TB cleaner around some vacuum lines that I know of, I'm sure I missed a few, and the idle didn't change. I then covered the whole TB opening and it died, so there isn't a vacuum leak inside the TB.

So I want to get the radiator flushed to rule out any air in the radiator, but luckily for me.....my cv joint is going bad now -______- so need to fix that first.

Also surging idle only happens after warm-up.

 

Do this same test on the FITV hole in the TB.

 

I don't think I have a hole for the FITV. Unless I'm completely blind, haha. Oh and I also tightened the little plastic screw all the way down in the FITV, so no leak there.

 

The stock 95 Civic has both an FITV and IACV:

 

Yes but what I was saying is that I only have one hole inside the throttle body, which I think leads to AICV.

 

Then you may have the wrong throttle body. Post a picture of the inside and outside of your TB.

 

OKay sorry I'm just an idiot...there are 2 holes in my Throttle body. When the top hole(AICV right?) is covered the car almost dies, but never does. When the bottom hole is covered(FITV?) is covered there is no change, but there is suction.

All was done when engine was cold, should I go ahead and wait till car warms up, and the surging idle actually starts to happen, or is that still necessary?

 

Yes, redo the tests when the engine is warmed up and the idle is surging.

 

Alright will do

 

Okay so here is the update. I let it run for about 15 min and it hadn't started surging yet, and was well into operating temp. It was on the otherhand hunting for a steady idle as the sound from the motor was changing slightly(barely noticeable). So to get it to begin surging I pressed on the gas pedal very slightly and only for about half a second. Surging instantly began.

When covering the IACV hole the car dropped down to a seemingly low idle and stopped surging. The FITV hole still had a small amount of suction, but it didn't effect the idle.

 

Assuming that you have thoroughly bled the cooling system, then test the TPS and ECT sensors. If those are fine, adjust the idle speed (see FAQs sticky).

Also adjust the FITV so that there is NO suction when the engine is hot.

 

Well I don't have anything to test the sensors with, I'm going to have the radiator flushed pretty soon here, as it needs it and that will for sure get rid of any air in the coolant system.

But because the engine idled fine after I plugged the IACV hole, doesn't that mean the IACV is messed up or something?

 

A toolbox for working on cars should have a multimeter. Get one.

Is CEL code 14 thrown? If not, you've cleaned the IACV, so I'll assume it's fine. Do the tests I mentioned and then adjust the idle speed.

 

Alright I'll ask around, I'm sure one of dad's friends has one. and no, no codes are thrown. Sometimes I wish one was so I would know what it was! Haha, but I'll do the tests and post back here as soon as I check everything.

 

Does the CEL work?

 

Yeah it has come on before, when I first bought this money pit... -_-
but yeah I may just buy a multimeter, aren't they only like 10-20 bucks?

 

I think Harbor freight Tools may now have a digital multimeter on sale for $2.

 

Okay cool, I'll pick one up tomorrow after classes and see what the TPS and ECT read.

 

Maybe air in the system? coolant ?