Hi all,

First post here, although I have been here several times to read up on different issues with my civic.

Setup: 1997 Honda Civic, Automatic, 1.6L MFI VTEC SOHC 4cyl, with no CEL.

The issue of the day is idle hunting. When I start the car cold it idles rather high for a minute and then begins to drop down to about 1200, and then shoot right back up again to about 2500, repeating this loop indefinitely. It will not idle normal unless I put it in gear. Then it settles down to normal.

I've read all about the cleaning of the IACV, throttle body and FITV valve, and I've done all of those things but it still does the same thing.

One thing I did find that I thought was odd was there is no wire to, or connector on the IACV. There is a receptacle for a connector to plug into but nothing there. I searched all over the engine compartment for a loose or tied back plug but found nothing. It's as if there never was a plug for this valve. Is that something that is normal on some models? I've had this car for about 7 years now and it used to run fine. Have never had any other maintenance done, excluding the routine stuff.

Anybody have any other ideas for what to check for the idle issue?

As stated above, check engine light is not on.

Thanks...RC

 

You cleaned the FITV? 97s don't have them. And that missing plug is an issue.

 

OK, I guess I cleaned what I thought was the FITV. Unfortunately the components are not labeled, so I'm only going by what I read and watch on youtube.

This is the item that I think is the IACV:

http://www.walagata.com/w/fubar94/IAC2.jpg



This is also the component that is missing the plug.

And this is the item that I thought was the FITV:

http://www.walagata.com/w/fubar94/Mystery_Valve.jpg

.

It's the valve attached to the front of the throttle body. I removed the throttle body and then disassembled and cleaned the different components attached to it.

 

What engine is in this car?

 

You have two IACVs because somebody swapped a D16Y7 TB or an auto D16Y8 TB onto your D16Y8 engine (manual).

This explains the idle problem.

 

https://honda-tech.com/forums/showpo...5&postcount=12

Also remove the passenger kick panel to see what ECU is installed.

 

That would explain why one isn't plugged up.

 

[You have two IACVs because somebody swapped a D16Y7 TB or an auto D16Y8 TB onto your D16Y8 engine (manual).]

Don't know what those are. Could you clarify them for me? Also, this car is in California and has been smog checked several times with no problems prior to all of this.

According to the VIN, the engine model is 1.6L MFI VTEC SOHC 4cyl.

 

Is EJ8 (D16Y8 engine) or EJ6 (D16Y7 engine) in the VIN?

TB = throttle body

Get the block, head, and ECU codes. Post them.

 

OK, I just realized that my previous post with the pics may have misled some people. Those are not pics from my car. They are just pics that I found online to use as reference for me to locate the components. I took some pics of my actual engine and will post them below for review. Hopefully it will clear up this issue about the dual IACV, as I have no idea how that could be.









The item in the last pic, with the black plastic body is what I believe to be the IACV. The item just below the throttle body air intake in the first pic is what I thought was the FITV.

Not sure where to find the engine and block codes but here is the vin which is what OI used to determine the engine model. The vin is 1HGEJ824XVL046394.


Thanks for all the help guys.

 

Are you trolling us?

 

Ron@HT, what do you mean, trolling? I'm not familiar with that term. At least, not in this reference.

I'm just trying to get some answers about this problem I have. I apologize if the original pics I posted have confused anyone. I didn't mean for that to happen.

 

Again, you seem to have a Y7 throttle body (with IACV) on what looks to be a Y8 that has an IACV mounted on the intake manifold (P2K).

Post the numbers that in the red circle and at the red arrow in this image.

 

grunblemarc,
OK, it took me a while to find those codes. Had to remove the heat shield from over the headers, and even then they were not easy to spot. I never really did see a code for the area where you had the red circle. There were four squares embossed into the metal but there was nothing inside of them. I snapped a [photo of the area to help explain what I am referring to.



The codes where you had the arrow are as follows:

D16Y8
6546287

There was also a tag with the vin # just below the area where you had the arrow, riveted onto the block.

Hope this helps...and thanks.

By the way, this car has an auto transmission.

 

You have a D16Y8 block and head. The IM has been swapped as an EJ8 auto should not have the IACV on the IM. You need the TB with an IACV attached.

 

So, are there two IACV's on this TB or not? What is the component that is just below the air intake port, attached to the TB? Is that the IACV?

Sorry, but I'm a little confused about all of this. Also, what I don't understand is why all of a sudden has this started? I've had the car for 7 years now. It has gone through several CA smog checks with no issues. Unless someone swapped the TB some night while I was sleeping, it is the same one that was on it when I bought the car. I know that doesn't make it right, but it did perform fine for all those years. Something must have changed. It runs perfect while in drive and driving it.

Thanks for being patient with me with this. I have been a mechanic on airplanes for 40 years, but I know nothing about these cars...it's frustrating. Guess I need to get a manual.

 

Now I know you're trolling.

 

I don't know why you keep saying that. I am just trying to diagnose a problem that I have with my engine. Since I don't know anything about these engines I am asking a lot of questions so that I understand everything so that I can make an informed decision about what to do to fix it. If that's trolling then I guess I misunderstood what this forum is all about. I thought it was about helping people with their car problems.

Guess I need to go somewhere else for help.

Thanks.

 

You're an airplane mechanic with 40 years of experience and you never thought once to get a manual for a car that you've owned for 7 years which you know nothing about so you can work on it? You don't know what a throttle body or an intake manifold is and you cannot seem to comprehend simple instructions/explanations. Good luck.

 

FYI, I have not needed a manual up until now, and yes I do know what a throttle body and an intake manifold are. I never said that I didn't. I don't work on cars for a living and therefore don't know all of the terms and acronyms that you guys throw around. I guess you expect that anyone who visits your forum for help is supposed to know everything already. Kind of defeats the purpose for the forum, don't you think?

You know, save yourself some time and don't bother responding cause I won't be monitoring this forum any more.

 

There should be one IACV on the entire engine and it should be located on the throttle body (TB). If there is also an IACV on the intake manifold (IM), then an IM from a D16Y8 with a manual transmission was swapped onto your engine. This set up can work if (1) the IACV on the IM is removed and the hole is blocked off and (2) the IACV on the TB is plugged into the electrical connector.

If you post clear pictures of the TB and IM on your engine, you can probably get further guidance.

 

Thanks Ron, but I just resolved the issue, thanks in part to your help. Your guidance to the fact that I had two IACV's led me to just focus on the one that was connected, which is the one attached to the TB.

Yesterday I removed that IACV and sprayed it with carb cleaner to clean it but that wasn't enough. I removed it again just a few minutes ago and realized that the little shutter door inside was frozen, so I sprayed it with some WD40 and manually pushed it with a small screwdriver until it broke free. Then it was able to move freely as it is supposed to.

I could feel that it must be attached to a Bi-metal spring at the end where the coolant flows through which I assume regulates the open and closed position of that door. So, what does the electrical part do? Is that just a solenoid to lock it open when it's cold? That'd be my guess.

Anyway, put it all back together and now it idles perfect, as it did before.

I only came back to post this resolution in case that it may help someone else down the road with a similar issue. I should probably point out that this only worked because I did not have a CEL on. I would imagine that if one has the CEL then the IACV is probably bad.

Thanks again.

 

Great! Glad to hear you resolved the issue.

The only reason that coolant flows through the IACV is to prevent it from freezing up in very cold climates. The control of IACV opening/closing is completely electrical. The IACV receives constant battery voltage and the ECU controls IACV opening/closing by supplying ground with variable resistance.

IACV failures are rare, even when an IACV code is thrown. The vast majority of IACV problems are caused by them getting dirty and seizing (like your problem) or by miss-wiring associated with engine swaps.

 

Ha, well that blows my theory completely out of the water. But, thanks for the explanation. It may come in handy sometime down the road. I'm just glad that I got it resolved. Now I just have to worry about whether it will pass smog check.

 

Good luck. Just post again if you need help with anything else.