Idle air control valve
 

My idle is ------ crazy sometimes its steady then the rest of the time it jumps anywhere between 1200-and 2500 RPM its just jumps and its annoying. Is that my IAC valve? or should i just adjust my idle? Thanks

Re:Idle air control valve
 

mine will bounce like that but between 700 and 1500 rpms and only when the motor is warmed up completely

UPDATE: tried vacuum hoses and no good, had a loose battery connection and now that it's fixed, no more problems ;D

Re:Idle air control valve
 

id guess u guys have vac leaks

Re:Idle air control valve
 

yeah, vac leaks definitely, if it was your iac valve, you would have a cel for it.

Re:Idle air control valve
 

I don't think its a vaccum leak becuase you would hear it. My Integra was doing it until I put a turbo on it than it stopped. My friends 01' Prelude just started doing it too and its very annoying.

Please update on how you fixed it cause' I'd really like to know

Re:Idle air control valve
 

iacv will not ALWAYS cause a cel. Take it off and clean it with some carb cleaner and put it back on. I bet the screen is clogged. You may want to replace the o rings on it also

Re:Idle air control valve
 

you don't always hear vac leaks, i had one so small that you couldn't hear it and it barely affected the car at except for a couple time, it was my tb gasket and it was barely leaking, but it was enough to mess with the iacv......

Re:Idle air control valve
 

this good and all for HIGH idles.. what about low idles? mine idles 100% PERFECT when cold 2k. but when warm it stumbles around 500rpm.

half warm its at like 1k - 1.2k smoothly. Anyone have some guesses?

Re:Idle air control valve
 

stumbels like minor surge or like a missfire?

MINI vac leaks can play hell So can a SMALL bubble in the coolant lines.


I have one on the 89 HB i sold my roomate i am still going thru that thing trying to find it i think its under the DPFI plate there is a o ring in there and a gasket i bet is shot on this one....

Re:Idle air control valve
 

yah the idle doesnt go up. it stumbles and falls to like 300rpm then kinda catch itself and go to 600 and then settle back to 500 again. but when cold or warming up its fine. i think my iacv is dirty or done. I've got an entire IM coming w/ tps etc.

Re:Idle air control valve
 

This is one of the MOST common problems with Hondas (no ----). Its one of 6 things:

1.) Base ignition timing too high
2.) Vacuum leak
3.) Idle air screw set too high
4.) FIV bad (stuck open)
5.) IACV/EACV (whatever you wanna call it) bad or clogged with ----.
6.) Older Accord/Prelude: the AIB (Start Air Boost) check valve on the drivers side of the Intake mani can get stuck open, just remove it.. it does jackshit anyway.

With the car warmed up to operating temperature: I start by jumping the service connector and pulling the IACV connector. I then set the base ignition timing and base idle (650rpm is where i try to get it with my external tach). I then shutoff the car, unjump the service connector, plug the IACV back in and reset the ECU via the backup fuse for 15-20 seconds. Restart. If its still jumping around I start looking for vacuum leaks. If I can't find any I swap on a spare FIV (I keep these things around ... I don't run one anymore, but my friends do) and that is usually the end of the troubleshooting session. Rarely do I see an bad IACV.. and you hope not to, because unless you have a hookup at a scrapyard they're like 150-250 depending on the model of the car. The last resort is to try and clean out the ports of the IACV and see if that gets you anywhere....

In my experience fixing this on probobly 20-30 honda's its been timing, idle air screw and vacuum leak that usually is the cause. Thankfully the cheap ---- :)

The way honda idles their cars when an environmental problem like timing etc is wrong its cycling the IACV causing the updownupdownupdown idle... very annoying. Sometime if you're in traffic notice how many Hondas do it! Tons of them.

Re:Idle air control valve
 

thats just the thing. mine doesnt idle up, it stumbles DOWN.. never over 600rpm at full operating temp.

idle, no elec load 600 rpm.
the fan kicks in cuz temps get up, idle drops to 400rpm and runs like ass... tough to describe the sound..

Re:Idle air control valve
 

4.) FIV bad (stuck open)


whats that??? Yea the worst i seen on a idle being messed up ws a ecu a fast swap solved the problem thats VERY RARE that the ecu screws up like that though..

Most I have done is Idle screw and clogged ass IACV where i am at people reuse evrything from friend to friend. Its a wonder how some of these parts make there way around lol. checked a few timings on them but i like yer mini write up.

Sticky Maybe?

Re:Idle air control valve
 

I would wager your IACV is bad... unplug it and see if the car acts the same. It'll toss a CEL but if it acts the same the IACV isnt doin anything. As you know it will kick up idle a bit for AC, highload electrical conditions and other things.

Re:Idle air control valve
 

http://cow.pasture.com/~bix/ebay2/DSCF0004.JPG

http://www.hondaautomotiveparts.com/...13SR80_D04.gif

This diagram sucks, but see #13? under the TB? That whole the large dingus is the FIV. Fast Idle Valve. It has a thermo-wax plug that when cold.. opens and allows more air into the intake tract to warm the car up quicker/help cold idle. As coolant temp rises the wax expands and closes it. What happens is over time the wax plug gets messed up and it sticks open or closed.. usually open unfortunatly and it plays hell with the idle... especially warm idle since the ECU is then in closed loop operation.

Some FIV's are on the bottom/side of the TB.. some are on the intake manifold itself. It just depends on the year/make of the Honda.

As you can see above I keep 2-3 of these on hand at all times... kinda like igniters and OBD0 distribs :P

Re:Idle air control valve
 

does the ecu read the o2 at full warm idle.. ?

Re:Idle air control valve
 

the only time it doesnt read the o2 is WOT and cold idle/warmup. at those times it relies soley on the 2d timing/fuel map.

Re:Idle air control valve
 

would a bad o2 cause crapy idle? my last emmiosions test was right on the limits of pass/fail. if that helps

Re:Idle air control valve
 

I guess anything possible... heh as they get old they don't go bad so much as they lose sensitivity. Do you have a spare to try?

Re:Idle air control valve
 

no spare. I just recently got the courage to do anything in the engine bay w/ my car.. interior and electronics are no prob.. next step is under the hood...

Re:Idle air control valve
 

I was having the same idle problem you are describing. I went through the whole, timing, IACV, FIV, vac leak test routine and turned up with nothing. I decided to chnage the 02 because it was old and I probably needed one. To my surprise it fixed it.
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Re:Idle air control valve
 

sounds like an easy thing to try.. any1 got an o2 for cheap??

Re:Idle air control valve
 

Hmmm..I have one form my Civic. Not sure if it will work for you? It's a four wire. :-\
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Re:Idle air control valve
 

nope im a 4g -----, 1 wire for me.... dustin says he can get one for 26 $!? (typo?)

Re:Idle air control valve
 

Yeah, I read that also. I guess I got raped on mine because I know I paid a lot more than that. :(
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Re:Idle air control valve
 

I was having the same problems.Idle was loping between 600 and 900 rpm at idle.

What I did was disconnect the A.I.C.V and with it disconnected I turned the screw on the T.B till it was at 500RPM.When I pluged it back in it was sitting steady at 600rpm.Havent had a problem since.

Re:Idle air control valve
 

tried that :( I think either my iacv is dead. the alternator load signal is messed or the iacv is too dirty to flow enough air under elec load.

Re:Idle air control valve
 

clean the IACV with Carb Cleaner or Seafoam, just let it soak for a while, reset the ECU and start her back up. If not, you can get an O2 on oxygensensors.com for $20, I checked earlier today, it's not a bad thing to have a fresh one anyway.

I did have an FIV go bad recently, luckily I too had a spare, the thing got stuck open and my idle was at like 2k, which sucks when you've got a loud exhaust. I'm switching to a B16 TB with no FIV, and then no more worries. I've got a few spare 02 sensors if you want to try a cheaper one, but you'd be better off with a new one.

Re:Idle air control valve
 

My idle is screwed up also. I have a black top DOHC ZC in my 91 rex. It goes from 1500 to about 600 and back and forth once the car is fully warmed up. I tried looking for a vacuum leak using carb cleaner. I didnt find anything. I replaced the tb gasket anyway. I cleaned the iacv with carb cleaner. But mine doesnt have a screen in it. Either did my friends on his sohc zc. Is that normal. When i unplugged the iacv the problem went away. Does that mean that piece is fine or broken. I still have to try the FIV thing. I also bought a new O2 sensor but couldnt put it on cause it started raining. Im so sick of the up and down idle.

Re:Idle air control valve
 

if and when u unplug the iacv the car idles perfect i'd think it was bad. when IACV's go bad then cycle. open closed, open closed.

Re:Idle air control valve
 

Well i fixed it. I replaced my throttle body with the one from my d16. Then it still kinda did it but instead of from 600 to 1500 it was from 1000 down to 100 then after a few of those it would die. So i played with the idle screw and it idles at like 1100 to 1200 but it doesnt do it anymore. Good enough for me. ;D

Re:Idle air control valve
 

good idea, if you replace it now, one less thing to worry bout later

Re:Idle air control valve
 

my crx(b16a) does the same thing idles up and down when its warmed up. i brought it to chester honda and they told me it was the idle air control valve so i got a new one. over 100 bucks later i put it in and it dose the same thing. but theres an adjustment on it wich i never messed with maybe that might do it. but its like 10 degress where i live so im not about to mess with it in this weather, maybe in a couple months.

Re:Idle air control valve
 

when the idle goes up and down when warmed it means you have a vac leak.

Re:Idle air control valve
 

i checked the vac lines, nothing no leakes. i cant stand that fn noise.

Re:Idle air control valve
 

check IM gasket, TB gasket, also check for little bits of fuel coming out from the injectors. also check the TPS sensor and Throttle plate.

Re:Idle air control valve
 

i did unplug my (idle air control) to see what would happen and it idled fine at 500 rpm's. i think that the valve i got from the del sol is probly just tuned for that car. so i just bought another iacv from a obd0 jdm crx for just 5 bucks, to see if that will hopefully fixs the problem. should be here in a week or 2. i'll keep you posted.

Re:Idle air control valve
 

You guys need to check your fast idle sensors. That's if your throttle body has one. I had the idle problem too. All I did was open up the fast idle sensor that is located under the throttle body and screwed the actuator in all the way and my idle problem was gone. Try that and if you need more detailed help just hit me up. ;)

Re:Idle air control valve
 

was that solution to fix a bouncing idle? or a low stumbling idle?

Re:Idle air control valve
 

Oh sorry that was to fix the bouncing idle on my 94 civic.