wallice

i've checked for vacuum leaks, change the iacv for a new one and still getting fluctuating idle. what could it be?

archie bunker

take it to the dealer. codes have to be cleared and it has to relearn idle by running engine for 45 mins. they replaced my IACV for free and its a 97 civic LX. they told me its covered by warranty. probably due to emissions

sql_civic

iTrader: (10)

You may have accidently mixed up the plugs that connect to the IACV and TPS. They are the same sized plug and will cause a rough idle if not plugged into the correct connectors.

turbo-2nr

replace the pvc valve. if you dont want to go to the dealer to reset the cel just un plut the ecu for about 10 min.

02BLKCIVIC

iTrader: (8)

how many miles?

bad cat?

Bacdef

Thank you kind sir ! The ECM really needs to relearn how to idle

wallice here is what happened for me and my 1996 CX hatchback, with D16Y7 engine. Those of you that would want to get straight to the point can scroll down to the 'What I did about it' section of the post.

It all started last January. The MIL light came on right after the holidays. The engine did idle a bit rough from time to time and the car was due for an oil change and a timing belt so hey, off to the dealer it went. The dealer replaced the chain and did the usual stuff, plus replaced the O2 sensor. All was well.

One month later the occasional rough idle was back. Since it was 20 belw outside I decided to ride it out until spring got here. It got worse. Two weeks later I had a severe rough idle and the car would even die on me from time to time on stop signs and red lights. No MIL, so I suspected condensation in the gas tank and did what everybody does in those cases. No good. The MIL finaly came on and back to the dealer it went. Replacing the MAP sensor cured that... Fair enough but with so much sensor business I was starting to think NASA should probably orbit Civics around Mars instead of billion dollar probes.

The new MAP carried me over to this summer without a hiccup, at which point the motorcycle became my primary means of transportation.

One morning thunderstoms were really raging and it was raining sideways, so no bike. Started up the car, drove to work and in the parking lot I noticed the revs were yoyoing between 1k and 2k. Further putzing around revealed it only occured on a warm engine.

I decided the culprit had to be the IACV since most everything else on the throttle body had been replaced. I pulled the the connector on the IACV while the engine was yoyoing and it immediately stabilized at 1.5k. MIL came on of course but that got cleared later.



What I did about it :

Step 1
I removed the Air cleaner, got the engine warm and yoyoing, put my palm on the throttle body's intake port and the engine died.
Result : No leaks (good)

Step 2
Went to a scrap yard and pulled an IACV from a dead 96 hatchback (5$). Took off the throttle cable, all connectors, both coolant hoses from the IACV and removed the throttle body from my car.
Result : Minor sunburn

Step 3
Went to the dealer and bought IACV o-ring and TB gasket ( 5$ each ). Removed original IACV from TB, cleaned TB, installed *new* cleaned IACV with new o-ring, put throttle body back in car with new gasket, connected everything and started it up.
Result : Steady idle à 1.5k with no MIL

Step 5
Play with idle adjust screw on TB.
Result : Can get it to yoyo again by raising idle up over 2k, cannot get it lower than 1.5 with idle adjust screw. Put screw back the way it was before I started playing with it.

Step 4
Despair, search web, read archie bunker's post about relearning to idle, start car and go for 15 min drive, park car, let it idle and WATCH THE IDLE GO DOWN TO 850, celebrate by blasting stereo.
Result : register on forum and write longest post evar.

I hope this can be useful to someone.

wallice : after having replaced the IACV you could try bringing the idle down with the adjust screw to see if it stabilizes at 1.5k like it did for me. If it does, reset the ECM and go for a short drive maybe ?

(edited for silly numbers and typo madness)

TRIZ

iTrader: (14)

You dont need to wait 45 minutes for your car to learn how to idle. Its like 6 minutes, although I did 10 to be sure. I think you drive around, get the engine warm, park it, turn everything off, start it up and let it sit 1- minutes without touching anything, like the radio or the gas pedal or breaks. shut the car off, then wait a few seconds, start it back up and go for a drive. Search idle relearn!!

Try resetting the ECU and the doing the idle relearn. (yank the ecu fuse with the car off & keep it out for 30 seconds or so)

Quicktime_GT

does civics have idle air control valve?

Bacdef

IACV=Idle Air Control Valve, therefore yes they do.

IACV model will vary according to the type of engine so they are not the same on every civic for a given year.

sql_civic

iTrader: (10)

When adjusting your idle screw you need to disconnect the IACV, turn on your accessories, and use a tach. Consult the Factory Manual for the proper procedure. Don't just **** around with the screw.

juan_p__m

Just as described before, soon after start up idle jumps between 1000rpms to 2000rpms, no engine trouble codes, swapped new Idle Air Control Valve, clean throttle body, idle adjust did nothing, switch signals to computer all check out, hoses and connections all check out. Can anyone help? Two years trouble free record has come to an end!

Changed the ECU for one on eBay, with no change in the idle. I did put a lage piece of rubber on the intake to block air flow and the car idle settled and continued to run. Now I am really puzzled. Do I have an intake leak?

sql_civic

iTrader: (10)

Check your timing and fuel pressure.

juan_p__m

I checked the intake manifold with ether, found a leaky intake manifold gasket. However be weary. If you perform this job, the Fel-Pro gasket has the coolant jacket copper ring installed in the wrong position. Will advice on how it turns out as soon as I get the proper gasket.

juan_p__m

Has anyone had a a warped intake manifold? my idle problem continues...

mugenpower89

dirty or bad MAP sensor disconnect da bettery n itll reset da ecu

JDM_HondaCivic

I've also got an idle problem...when i start the car, it will idle at about 1600-1900 revs. But when i start to drive it, the idle will go back to normal. It only happens when i start my car...I was wondering if anyone out there can help me solve my problem? It would be a great help. Thanks.

moolieboy

Here's a video that I found useful about Honda Idle Problems.
It is made by Eric the Car Guy.
http://www.youtube.com/watch?v=L788j...layer_embedded

It helps.
Granted, he's not as good as some of the writers on this forum but it's still pretty enlightening.
And it's Video.
b.

genghis1

Good info, thanks

dpcpeoriaserver

i never had a warped intake manifold but i did have a bad gasket. that will raise your idle and if it gets bad enough will fire a p1399 cel code for random cylinder misfire. my felpro gasket was fine and it smoothed out my idle. whats happening is the iac valve is attatched to the manifold. the whole seal as a unit is messed up so its not getting the vacuum that it should inside the maniflod so the iac valve is not going to work properly until the main cause of the problem is fixed

petesporn

i have a 2000 civic and the problem Im having is that as you are driving the car is fine, as you approach a stop the idle drops and feels as though the car is going to stall.

juan_p__m

Never posted my repair to the 96 fluctiating idle, purchased a dealer intake manifold gasket, and the fluctuating idle problem was solved.
Now dealing with my Mom's 2000 DX at normal operating temperature, i load the engine withthe power steer and the idle drops from 800rpm to 600rpm with the engine stalling at idle load, seems as it is being starved air or fuel, any one has any ideas, the MIL had given me a PO135, checked the ohms and the sensor failed, replaced the oxygen sensor and MIL has now gone, but the idle still drops. Any help would be apreciated

jturiak

Try this...remove the throttle body to get access to the air intake control valve. Remove it and spray it with brake cleaner or carb cleaner till the liquid isn't black anymore. Let it dry and replace. My son cleaned his '98 Civic this way (20 minutes) and the idle was back to normal!

gseattle

Seems to be a common problem. Mine is fixed and was merely a hose.

My situation at least: Hairline crack at the bend in the hose at the top of the intake manifold toward driver's side. As a test I removed one end of it and the RPM fluxuation problem maxed out dramatically. Then replaced the hose and that appears to have solved the RPM fluxuation problem for me.

The hose is maybe 8 inches long, about 1/2 inch diameter, 1/4 inner diameter, with two nearly 90 degree bends in it, runs from the top of the intake manifold toward driver's side to the lower part of the intake manifold. To replace that hose I bought a foot and a half of fuel line hose from the hardware store for $1.50 and looped it around to avoid those drastic turns. Might look funny yet solves the problem at least on this 1995 Honda Civic Cx hatchback.

You might want to try removing one end of that intake manifold hose and see if there is any change in the revs problem, fluxuation in the RPM's.

Demoncivic

I just bought a 98 model and I have to fix some suspension stuff... I noticed I also have the fluctuating idle. While I was fixing the suspension today I noticed some dumbass had replace a part of the exhaust where the o2 sensor goes with just a peice of exhaust pipe and just left the sensor hanging... Is this the cause for the idle problem? if so how can I fix this without having to go buy a whole new exhaust system?

Demoncivic

For those that may still be having probs with this after cleaning the iacv, I cleaned my icv and stil had probs. I revved the motor to about 5000 rpms 3 times and the idle leveled out and havent had a problem since...

33Strings

I'm not sure if what I'm experiencing with my 2001 Civic is a similar problem or not. I will drive it and from time to time it will suddenly feel as though the RPM's went up even though the tachometer doesn't show any jump. At the same time I will have a large drop in power to the point I can't really get over 20-25 mph. If I park it and let it sit for about 20-30 minutes it then runs fine. It idles roughly when the problem is occurring as well. I stopped using the a/c in the car and noticed it went away but then when I drove out of town yesterday (1.5 hours round trip) it happened again even though the a/c was off. I'm not getting a check engine light. The temperature gauge on the car was fine but it smelled like something was hot when I got back. I had to get to work so I didn't have time to take a look right then. (Drove other car to work.) Any insight would be appreciated.

bisso

I just want to reiterate how important it is to properly burp your coolant after draining the anti-freeze. After doing a flush, it took 20 minutes of run time before I stopped getting bubbles and having to add coolant. The car idled better and better with each cycle. Remember to keep the heater on hot so coolant cycles through the heater core. PS...the temperature sensor will malfunction if the metal probe is tarnished. You don't have to drain the fluid to check it. It is located next to the upper radiator hose. Just pull it, plug the hole with some gum - I used a gum eraser - and hit it with some fine sandpaper to recondition. Also remember that thermostats go bad more than most parts so if your idle is inconsistent and its been awhile, go ahead and change it. Remember, you might have two or three things contributing to your hunting idle problem. On my 92 civic si, it was a tarnished temp sensor, air in coolant system, and a damaged seal around the thermostat that was allowing coolant to leak past. Now the car idles at a smooth 800 rpm and only temporarily holds at 1000 after hitting the gas. I believe this is exactly how it should run.

Scriby760

I FOUND my problem. So first, I spent $40 on a new IACV because I thought code 14 was relating to that, but then realized it can also be a vacuum leak or another sensory problem, and rarely have I had sensors go bad. So after installing the new IACV and the problem Still persisted I decided to check one-more time for Vacuum leaks. It turns out between a cheap ebay gasket kit, and a rebuilt head with metallic paint on the intake gasket surface the paint deteriorated and the gasket ripped likely as I was installing it. No parts were bad except this intake manifold gasket. Went to Oreilley Autoparts and bought a new Felpro intake manifold gasket and popped it in the same day within about three hours after scraping the paint away from the gasket surface on the head to make it clean. Walaaaa, hope you find that leak somewhere if you recently rebuilt your engine with a cheap ebay gasket kit they were all fine to install except for the one on the intake manifold. PROBLEM SOLVED for me....Thought I would post to help somebody else out as well. BTW you can barely see the tear in the gasket will have to spray something, mine was on top right next to cylinder 1 where it ripped upon installation.

steveT

Okay, I know an old post. I have battled the idle issue for 6 months and replaced parts and fixed vacuum leaks like like the rest of you. Bottom line it is the IACV that is your problem. Buy an original Honda part. I bought two after market ones and problem still there.
D16Y8 motor MT place tinfoil between IAC and throttle body. Adjust idle screw to 550 RPM base idle. If that works then then the after market IAC is crap. If you do not want pay 2 to 3 hundred dollars for the OEM part then try this. Place two 1/16 to 1/8 holes in the foil where the air ports are and bolt back together. I used aluminum flashing and made an interface plate. The problem is the cheap ebay after market IAC's do not fully close which is why even with your idle screw all the way in will not reduce the idle. Yah you can retard the crap out of the timing to make it run and not throw a code but gas mileage and performance is crap. My old 1999 civic has great performance and is getting great mileage without replacing the china knock off IAC.
I only registered to pass this along since I had such a tough time and noticed too many unanswered posts on fixiing the problem. Don't get me wrong, I did have bad intake gasket, PCV hose and another vacuum line.
I changed the IAC twice with non OEM. I learned my lesson. Also tried an after market knock sensor too. Nope bad move. Pain in the neck to change and not worth doing twice.Hope this helps you folks that never got a final answer.

Jesshaines

hi, if theres anyone still out there in this long dead thread - im having this same problem with ring in wrong position. How did you end up resolving this? Ive checked three sites and all have same part. Do you know correctbpart number? Thanks