hdragster

lol how about make a youtube video for us visual learner XD

simione

Hello all. I swapped in an accord euro r motor into a 1996 honda accord. I stayed obd 2 and kept the 3 wire rotary iacv. I am using a obd2 a to b harness and using the stock euro r ecu. The third wire of the iacv was wired into my existing harness. My problem is that I am having a surging idle after the car reaches full operating temps. I have replaced the tps with a known good one, replaced the ect sensor, and I cannot find any vacuum leaks anywhere.Coolant has been bled thoroughly as well. It is starting to get really frustrating, as I do not know where to look next. Should I pull the plate covering the egr ports and clean in there next? any input on this is greatly appreciated! This is a great thread!

homoaranea

Bought a '92 Prelude S Oct. '07 with 210,000 miles.
Here's the upgrades the previous owner made:
K & N Cold Air Intake
DS Sports Exhaust Manifold
2.5" Magnaflow (manifold back) Exhaust

About five months after purchase, it developed the idle bounce. I'm quite mechanical, but have no diagnostic experience, so I asked a tuner friend for suggestions. He pointed me toward a bad IACV. So I bought and installed a refurbished one, no help. I took the car to my local Honda shop and asked them for a diagnosis. He found that the # 1 cylinder was not firing. He said this imbalance in power was causing the ECU to try and compensate, hence the bouncing idle. He gave me list of possibilities:

Spark plug gaskets were leaking, allowing oil to penetrate the spark plug wire leading to arcing inside the spark plug tube.
Need new cap, rotor, and plug wires.
And finally, have a bad head!!!!!!!!

I replaced each item cheapest to most expensive. Each new item did nothing to solve the problem. I decided to bite the bullet and found a rebuilt head online.

Having never replaced a head (or anything that complicated before) I bought a CD-ROM of the Chilton's Book off eBay and dove in. It took me approximately 7 months of working on it when I had free time and dealing with certain issues that came up. The worst was a stripped head on one of the head bolts.

Once I finished and everything was back together, I fired it up and Voila, no more idle bounce!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I've since driven the car for around 15,000 miles, including a 600 mile round trip to Eastern Oregon last October.

Two weeks ago, the idle bounce returned. I am super pissed!!!!!!! It idles really high when it's cold, then bounces when it's at operating temp.

I tried plugging the IACV and FITV holes in the intake, they both "fix" the bounce. I checked the FITV ring, it was about three and a half turns loose. Tightened that and the high idle when cold went away. Can only figure the IACV screen filter is dirty or something since its all but new, no luck, clean as a whistle. No bubbles in the coolant system. (Can you tell I've read this post backward and forward?)

I am at a complete loss. I have no codes, which leads me to believe it's not: Throttle Position Sensor, MAP Sensor, Intake Air Temp Sensor, O2 Sensor Engine Coolant Sensor, or any other sensor conected to the ECU. That leaves the IACV, FITV or some kind of Gremlin living in my car that needs to be chopped into forty pieces and fed to the neighbor's dog.

Unless I hear some other suggestions, I guess I'm just going to start replacing the IACV and FITV and then sensors one by one until it goes away.

Thanks for reading my book of misadventures.

gstrudler

Hey neighbor, tough luck. Does the car behave normally otherwise? Could be a blown headgasket again. I would first recommend a leakdown test to let you know if there's a problem with the gasket or head before you start replacing parts again.

homoaranea

Neighbor indeed... It has now developed a miss-fire at idle (when its smooth). Aside from that, it runs fine.

What makes you say "headgasket again"? Do you think that was my problem before? The mechanic at the Honda shop said he checked for that, not sure how. I put all new gaskets in when I replaced the head; I find it hard to imagine it could have blown one so soon. I don't drive it real hard... it rarely gets above 4500 RPM.

How does one go about a "leakdown test"?

Man, I wish I had some mega-cash lying around, I'd just throw a JDM H22 V-TEC into it and be done with all of this... oh well, back to reality.

Thanks for your input.

gstrudler

I would find it odd that the head itself was bad without the headgasket having any problems, which is why I said "again."

Do you have a Helm's manual that you did the head/headgasket replacement with? Was the head measured for flatness? Did you retorque the head after a heat cycle? The miss at idle definitely makes me suspicious too. I know because my hg is toast and I get a miss at idle after I've been on long trips (2+ hrs). Usually it will go away after a couple days of driving around town. I find it actually goes away better when getting on it a little instead of being ginger with it.

There are writeups on here for how to do your own leakdown test, but a trip to the mechanic or dealership may be your best bet, the test should be around or under $100.

punxsk8r555

Well i recently put a jdm h22a engine in my girls lude. it had the jumpy idle and when it was warmed up if i plugged the top hole in the throttle body it would stop the bounce. so i just got a new iacv today and just got done putting it in but it still does the same thing. every line is connected and there are no leaks anywhere. anyone else got any answers? could it be something else? and is there any way to check iacv?

H duce duce

did any of you try cleaning the map sensor?

minilogoguy18

Thought I'd bump this thread rather than making a new one, put in a fresh JDM H22a not long ago and it had a high idle at cold and a big bounce. Tried adjusting fast idle but I guess it was shot and also somehow lost the cover back plate while driving and so I replaced it with the H23a1 FIV and had a friend at the Honda dealer adjust everything and it mostly fixed it. Still had a very slight bounce when cold and only when cold. The IACV has been cleaned and I figured if that was shot then it would throw a CEL which I'm not. I noticed though that I never had an air boost valve and figured the H22a didn't use one but it does have a place for it with what looks to be an OEM block plate. Could the lack of an air boost valve be causing this slight flux or can the IACV only throw a code when the ECU doesn't detect one but it still is bad?

si_motor_spt

Hey all, i have a 97 prelude, all stock wit 147000MI, my problem is that when the car is warm,when it trys to idle on its own, it dies out, and when i try to start it up again, i have to give it some gas to keep it alive, when i start the car when its cold, it starts up fine but its just when its warm it acts like sh*t,please help, i already tried cleaning the IACV and nothing,took off the vac line to the egr and nothing,LMK please,mahalos

si_motor_spt

i knew my problem was that 1% out of everyone else issue...no help?

gstrudler

Have you tried adjusting the idle set screw on the throttle body? Sounds like it is set too low. The car stays running when cold because there is extra air flowing in through the FITV, which is closed when the car is warm. Unplug the IACV and set your idle to a little above 500rpm.

smackdown

brah ...it sounds like a bad main relay it happened to me too, just resolder the points and you good to go guaranz..

REDNECKGIRL

Ri'can Luder

I did everything but check my vacuum lines. My idle fluctuates from 1k to 2k. When I plug this hole in the throttle with my finger it goes back to normal. Whats that hole for/from/go to.


Then I got a used IACV from ebay and it's still the same, and now it revs even higher after doing some "spirited driving". It goes from 1-3k, I also bought a new throttle gasket and same. And here's a vid I made, hope someone replies.
YouTube - 92 Prelude Bad IACV?

dubulc

great write up
i have this problem on my 92 prelude si and unplugged my IACV and it just dropped the idle down but had the same problem
so i turned the engine off and back on and then unplugged my Throttle Position Sensor cause when my idle started to surge my cruise control stopped working too and it stopped the surging
so my TPS is bad

so if anything in the write up didn't stop the surging also try unplugging you TPS to see if that might be the problem
it was for me

projectTeG

take the fitv off and screw it closed or block it off.

also check to see if the Internal IM gaskets arent bad

Redbaron2

Tightneing the Wax in FITV fixed my idle bounce.

While accelerating the car jerks, also when decelerting too. I cant figure this out, IAC cleaned and seem to work fine. Did this before work on FITV and IAC.

Is there some sort of smoother device while accelerating or decelerating I should check?

Ri'can Luder

Fixed my problem, it was the intake manifold gasket.

Potter92

i have followed this article step by step.. bought a new IACV, cleaned MAP sensor, cleaned the throttle body, checked for vaccuum leaks, plugged up the bottom hole on the inside of the TB and it stopped a little bit but it just made the engine die. i am ready for this problem to be over with. i have been trying to fix for the last 5 months. i am ready to just set the car on fire...anyone have any other ideas?.

info...idle surges from 1200-2000 rpms...if i don't keep the gas pressed, around 1500 rpms it makes the car jerk very bad. other than that it drives perfect. please help!

Ri'can Luder

If you plug the bottom hole in the throttle body and it goes back to normal you need to adjust your FITV. If you plug the top one and it fixes it then you have a vacuum leak or need to clean your IACV. If you do both and it stays the same check your gaskets.

RanchoHonda

Thanks for the thread. I followed your suggestions. Closed lower opening with finger and no change in bouncing idle. Closed the upper left with finger and the idle smoothed out. It sits halfway between the 1 and lower hash mark right next to it. So I'll take the IACV off again. Clean it, check for broken parts and install. If problem still exists then I'll have to but a new one.

Thanks again.

Ri'can Luder

No need to buy a new one. Try looking for a vacuum leak and changing your throttle or intake manifold gasket. I got an extra IACV because I instantly thought that was the problem. Go with the cheapest first.

91lude4ws

this thread is a life saver. i never would have thought to ever check my FITV. thank you very much for this incredibly useful thread!!!

H23_Lude4_2_0

hmm i need to take a day and dedicate myself to doing this.