olish79

So there I am, with a well known idle problem...
Before you think I am like a no reader, I guess let me explain to you everything, then we can talk.

I have a rought idle all the time, between 1000/ to 1500/, up and down.

I bought the car with the problem, full stock.
I have read a lot on idle problem before I bought it so first day, took of FITV, IACV, cleaned it properly, screwed the white plastic in and everything. Did empty and changed the coolant and everything. That's where it stars...

BTW at that time I intalled an integra intake, didnt changed anything. Obviously. But just so you know what's on my D16Z6.

So I decided to buy an IACV, and a FITV, and Map sensor and PCV valve used from a car. Received it, didn't changed anything.
I got one from a friend, used, and that one does something better. Still idle 1000/ 1500/ but when hot it idles fine at 900/ 800/. It does search for idle when hot starts but then 5seconds and it goes 900/.
So I choosed to buy one brand new. Received it, and rought idle again from 1000/ to 1500/ constantly.
So now I am driving with the kinda good one when hot.

Miracle happened once, dont ask me why and how but for like 3 days the car iddled fine, I mean i started straight at 900/ even cold starts so not that good but nice idle.
it only last 3 days tho...

So I changed a lot of parts, due to this problem but also due to the 20years she has already.
Let's start from gasckets, intake and TB (thermal one), IACV, Map. (brand new)
Injectors were changed and switched.
I review the fuel gas line. Didnt changed the fuel filter but looked clean to me. Checked the fuel pump, works fine.
Changed full Delco head, rotor, spark plug and wires.

I decided to by pass the FITV and take it off like they do on skunk2 TB. Just to make sure the fitv wasnt faulty. Didnt changed anything.

I decided to by pass the IACV, the lines are supposed to keep it warm, i live on island and it goes down to only 10° here so I am not worried about that one. But still didnt changed anything.

I spayed start pilot all over, didnt do anything and it didnt really change the idle.
I obviously took all spark plugs and check for engine sound change, they all made the sound change.

There is the test when you put your fingers on the holes inside the TB and it does go idle fine when i cover more than half that hole.

Last weekend I opened the harness from the iavc plug to as far as all wire get together.
I will try to test the continuity from the plug wires to the harness big plug if I find where it goes.

What else... I did so much stuff to check what was wrong, I even teste the alternator and looks fine.

SO any ideas will be taken.
I will answer all your questions if you have some but yeah pretty much I dont know what to check next.

Even mecanics cant find it so I will do it myself.

thanks in advanced


HONDA DEL SOL 95 - EH6 D16Z6 1,6L

TomCat39

Air Intake Temperature sensor wasn't mentioned. Also temp sensor on the head that goes to the ECU can cause idle issues.

https://honda-tech.com/honda-civic-d...ffect-3249080/

olish79

Thanks for that answer and for the link.
Any how to troubleshoot thoses bastards ?

TomCat39

You haven't googled for the fsm? I assumed you've been working with the factory service manual in hand.

olish79

yess indeed I work with the manual mostly and google sometimes to get ideas but you know sometimes doesnt make sense to me.
But yeah Ill try to take the sensor off and check how it looks. its supposed to be scewed in. Any way to cehck for sure if it does good ?

I forgot to talk about the timing belt tho, I checked it and its properly intalled.... and whn I unplug the IACV it does iddle fine, but I am not trying to drive without it.

And I do check the CELL, who's always 14. IACV

TomCat39

If your CEL is saying IACV circuit then you need to do all the troubleshooting procedures in the FSM for the IACV, not just swap it out. It can also be the circuit not the IACV unit itself. So that also means continuity testing of the wires between the IACV and the ECU. Corrosion on connectors etc etc.

The FSM runs you through a full troubleshooting chart.

The IAT is white plastic nipple essentially. I would think if it has oil sludge thick enough it could prevent a proper reading of the air temperature.

The temp sensor on the head also has a trouble shooting flow chart if I recall. If it's not working properly, the ECU is going to run the car improperly as it thinks it's always cold most likely.

The IACV and the ECU temp sensor (not the temp gauge sensor) both have trouble shooting guides in the FSM if my memory serves me correctly.

olish79

thank you. I'll do the seach tonight when I get home. But I tested continuity, 12v knowing that the IAVC works with a 12v constant and the ECU cut or put the ground to open or close it.
I actualy never tried the Voltage with the IACV plugged in, that's the note I have on my to do list. Only tried it unplugged with meter in the connector.

To take of the sensor off the head, I would think I have to bleed the cooling circuit... ?
anyway I'll go throught the manual again.

but thanks again for the tips and tricks. Ill try to work on it when its not rainy

MisereNoire

Another idle issue and one of the MAIN culprits gets left out...so here you are:

Get your IACV CEL issue fixed so that it wont be affecting the idle.
Then open up your fsm, go to page 11-123 and adjust your throttle cable, once that is done, head on over to page 11-102 and follow the procedure for adjusting your idle...800-900 rpm when warm is too high, and anything higher than that is totally wrong. 650-750 rpm at operating temp under no load is correct, 760-860 rpm at operating temp under high load (brights + hi blower + A/C on) is correct. If your idle still bounces after all this, you should follow the troubleshooting flow chart in the FSM for a complete testing procedure on the idle circuit.

olish79

Arf sorry I forgot to mention that I did already put my idle straight and the throttle boddy close perfectly... TPS was tested also wwith Ohm.
If I take off the IACV I'm between the right numbers...
but the CELL 14 doesnt show up when it is hot enougth, its nor constant, even when hot it does search for steady idle then goes chill at 900/ 800/..
It does come on when there is no CELL when I turn A/C on tho.

Sorry that I didnt mention all of this in first post, I have been searching for months...

TomCat39

You say you have the FSM so I didn't think I had to post the pages but you need to work through the troubleshooting processes in section 11.

Here is some of them mainly for the EACV/IACV:

olish79

I tested, following the manual, kinda everything I could, V,continuity, resistance on all intake sensors, everyhting is in specs. I obviously dont have the harness test to I check what I can with the Ohmeter....
SO..
Could'nt reach the 420 +-50 RPM when trying to settle the idle scew, same as usual, even if I close it complitely, just so you know.
I will bleed the coolant and check all temperature sensor on the cooling system and eveything AGAIN.

Any other ideas ?

olish79

Still stuck, any takers ?

I am going to a garage on monday to test compressions on cylinders and fuel again just to make sure.

How about my clutch ? it sounds a little strange to me at that time but bought the car like that so I dontk now really, just thinking out loud.

feel free to post

TomCat39

Did you not look at page 11-85? There is a long list of items to go over.

tony_2018

If you have a cel for IACV than it needs to be diagnose. Tossing used parts at a car and stating that its good to go are some really bad descriptions of you troubleshooting the issue. Follow what the ThunderCat has posted.

olish79

as I said I did the troubleshooting for the code 14 'besides the fact that I do not own a harness test.
and I pointed out that the Cell 14 doesnt come all the time, if the car is hot the cell wont show up. On the SM it says intermittent problem.....
But I did do the troubleshoot following the Service Manual.

BTW guys my house is open, so if you want to come in New Caledonia and re do it with me, I don't see any problem with that !

Former User

When the idle is surging and code 14 is thrown, remove the intake system and use your finger to cover the hole leading to the IACV or FITV inside the throttle body. Does covering one of those two holes drop the idle speed and stop the surging?

You also need to add car information to your first post.

olish79

I just edited the first post to put the kind of car I have.

About the test regarding the holes in the TB. First the FITV's hole, no need to ask I removed the FITV (wayy after I had the problem obviously) so no problem with that one but yeah when I put my finger and cover about 79% of the upper hole idle goes smooth. If i cover it fully it stall.

Former User

Test anyway, just in case there's a leak past your jerry-rigged seal. Once the idle issue is solved, reinstall the FITV. It's needed.

^IACV hole, right?

This result rules out a vacuum or intake air leak.

1) Attempt to adjust the idle speed to spec as per service manual instructions.

2) Ohm test the ECT sensor.

3) Voltage test the TPS at WOT and closed throttle.

olish79

about the FITV, its only for cold start normaly, so I live in island the less we have is 10° and I let it warm up so dont really need it,
About the IACV hole, we are talking about the same one
ECT, AND sensor of air temperature ok tested with Ohm same for TPS, but i'll check again I dontreally care...
Tried to work on the idle speed following the manual but only when hot I can reach the 420 rpm but cold, impossible, just to you know, but SM says to do it when hot after 2 round of fan starts. So it is done and in specs when hot.

still didnt change anything, but no worries tomorrow I will try again the Ohm for all captors and settle the idle speed again, i dont care.

TomCat39

TPS isn't an ohm test, it's a voltage test.

olish79

exactly with the three branch test following the SM, sorry about my misstyping.

So compression test is ok, they all have arround 9k pressure for each... so no problem there and test was done properly but mecanics. just so you know.

QUICK QUESTION :
Can I just remove all by pass hoses that go from the valve cover to block (the ones that start from Valve cover and normaly goes to FITV then IAVC then block) ????
[Before anything, I just want to add that I had the problem with all of hoses on]
I am asking this because I will empty the cooling system and check all sensor again tomorow.

TomCat39

O.o

You are going to run the car with no coolant??????

Are you trying to destroy the engine?

tony_2018

...and its not even part of the fsm diagnose tree.

olish79

WoW ok guyes take a break, and do something with your brain. I am here to FIX a idle issue not break the car or do stupid things... facepalm*

So obviously I need to bleed the coolant when car is *obviously* cold and mounted on stand. obviously*. I will chech how they look from inside and I do need obviously to bleed the coolant so I can unscew everything. obviously*

The quick question was about the by pass hoses that you can find on the FSM obviously that fo throught FITV and EACV. just so you know.

I am here to fix my case, that's all

TomCat39

Look, it's plain you aren't familiar with the site with your demeanor and 13 post count.

If you've been here awhile you will see and learn and begin to know just what kind of not so smart things get posted up sometimes.

The way you wrote your statement, and with the history of the site, I can't just "assume" your meaning.

Saying do something with our brain is you wanting us to give you the benefit of the doubt against your misleading writings when you haven't even been around to 1 display what you do and don't know aka competence levels and 2 seen what we've seen so as to communicate concisely so as to not look like some of the not so smart things posted here sometimes.

I understand you are here to fix a problem, most people are. You just wouldn't believe what people think will fix a problem that usually only makes it worse.

The coolant hoses to the FITV and IACV can be bypassed, however your FITV and IACV (EACV) won't function correctly so it won't "fix" your problem.