courtney42

I cleaned my IACV out and it is still wavering at start up. It's really annoying and you guys can help. I searched ebay and noticed that there are allot of AICVs for 94 - 97 accord for sale. It looks identical to mine. Has any one ever used one on a D15b or know if it will fit? A new one is 160$ ouch

RTI

I would first check your fast idle thermo valve (FITV) if you have one. This valve increases idle airflow around the throttle valve when coolant temperatures are low. Not sure about D-series, but my OBD1 B18 had oscillating idle, only when cold. Too much airflow through the valve when cold can cause the idle to oscillate. When warm, valve is closed and problem goes away. Based on your description, this sounds like your problem. There is a good how-to with pictures somewhere on this board if you search. Before you buy a new idle air control valve (normally called IACV, not AICV) I would make sure your FITV is not the problem.

courtney42

Ah found a good one. Hope mine is in the same location. Here is the link for everyone:
https://honda-tech.com/forums/acura-integra-6/%2A%2A%2A-how-%2A%2A%2A-clean-your-fitv-aka-fast-idle-thermo-valve-1564019/

courtney42

Well i cleaned it the FITV all out and put it back on and the problem still remains. ??
Every time i start the car "from cold start" the idle bounces from 1k - 15k until i drive down the road a mile and the car warms up?

Does any one have any more suggestions on what could be causing this?

Former User

Is the CEL ON?

Have you bled the cooling system?

Does the idle bouncing stop if you cover the FITV port inside the throttle body with your finger? Does it stop if you cover the IACV port with your finger?

courtney42

I am not getting a cel at all. The covering the hole test? I will try that and report back.

On a side note i noticed when i dismantled it this plunger part:


It screws out with a flat head. It was not screwed in all the way. 2 threads were showing through one of the ports. When i reassembled it i put it back the way it was. Is it supposed to be screwed all the way in? I noticed when it is not screwed all the way down there is a little space between the brass and the plastic where fluid could still pass. If it is closed is it supposed to be all the way closed?

Oh do you think a coolant flush would do some good? When i bought the car it had been sitting. I drained out the old and put fresh in but i did not have any pressure flushing out any crap.

Former User

Have you read this FITV thread?

RTI

This seriously sounds like it is the FITV. With the FITV removed, thread the white part so that there is no gap (i.e., make it touch the plunger). If the problem is the FITV and you have made the gap too small you can adjust it again later.

courtney42

I'm not sure what your telling me to try?
Screw it till the brass plunger is touching . . . What are we looking to happen when i do this? How can we tell if it is the FITV?

RTI

The FITV works by allowing air to bypass the throttle when the engine coolant is cold. It throttles the air through the opening between the brass plunger and the white plastic part. That brass plunger elongates when coolant heats up, eliminating the gap between itself and the white plastic part. By threading the white part into the plunger when cold, you will be preventing any additional air from entering the engine when cold. Your fluctuating idle sounds like it is caused by too much air entering the engine when cold. This is the reason why some have told you to cover the holes in the side of your throttle body with your finger as a check. Those holes allow air to bypass the throttle valve. By eliminating airflow through the FITV, you are effectively doing the same thing.

joelmatt89

+1 I didn't read the other comments to see if anyone answered your question about whether or not the white plastic fitting should be screwed in all the way but the short answer is NO. But re-read the thread you put a link to he explains it underneath the third picture from the bottom.

courtney42

This is exactly where mine is. But he explains that it will adjust idle that is to high or low. It doesn't say anything about fluctuating. I will try to cover the holes with my finger today and see what happens. If the idle levels out when i cover the hole i guess i should tighten the plastic part? Is this correct?

joelmatt89

yeah you can't adjust the fluctuation by adjusting that fitting, the problem is likely somewhere else but i have a similar problem that i have given up on for the time being while i am working on other things so keep us posted with what you find

RTI

Threading it in all the way is not the final answer to the problem, but it will show definitively if the FITV is the problem or not. I am pretty sure that it will need adjustment to reduce the airflow during cold startup.

RTI

That is correct. It will adjust the cold idle up or down but what is not obvious is what happens when the cold idle is too high. When cold idle is too high due the FITV being adjusted incorrectly, the idle begins to fluctuate as the ECU tries to correct (via the IACV I think) for the excessively high idle. When the coolant heats up and the FITV closes, all is good. This is why I said to thread the white part until there is little or no gap. If you do this and the cold idle problem is the same, it is not the FITV.

joelmatt89

See the thing with mine is it fluctuates once it is warmed up but i did adjust the fitv out to make it idle higher cause that actually seemed to help the problem a little. But maybe i will try adjusting it some more.

courtney42

Ok , i threaded the plastic piece all the way as far as it will go. Looks like there is no gap. I put it all back together and i think the problem is fixed. I started it up and didn't hear it bouncing at all. I waited till it got to temp and still no problem. Idle holds steady at 900rpm from start , and quiet as hell.
But i did drive the car a couple hours ago. So tomorrow will be the true test because it will have been sitting all night.

If it is fine tomorrow morning does this mean it is fixed or do i still need to buy a new FITV?

Another question. I filled the radiator with fresh fluid a while back but the stuff coming out of the tube when i disconnect is brown. Should i get it flushed? Could this be adding to the problems?

RTI

Threading it all the way was to guarantee that it was the FITV adjustment. Since your cold idle and warm idle now seems to be the same, it worked. If you want to, you can open up the gap a little to bring your cold idle higher than 900rpm (around 1100 to 1200 maybe). However, open it too much and you will be having the same oscillating idle as before. You do not need a new FITV. Even if you bought one, it might need adjusting anyway.

Not sure if you are talking about the tubing to the FITV. You should be bleeding the air out of the coolant after working on the FITV. I doubt coolant is related to your idle problems.

courtney42

Well if it is brown it means i need to flush it out and put fresh in again.

Thank you all for the help! We have success!

courtney42

Ok i started it up this morning from sitting all night and there is no idle bounce any more. BUT. . . . Now my tach does not work. Is this because i screwed the plastic thing in all the way and left no gap? I'm kind of frustrated. I cant stand a non working tach. Any one heard of this happening?

civic_driver

Make sure that you didn't bump the tach signal wire that goes to the ignition coil. You might've bumped it when you were working on the FITV.

courtney42

Everything is still connected. I jiggled them to make sure but still no tach.
I started a new thread for this tach problem. Please lend some help there.
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/tach-stoped-working-2540084/
I don't know how to fix this one or even where to start.