jdmvtec7700

I had this a while ago and just want to add the following.

Unplugging the IACV fixed my problem, however it was not bad. I had a vacuum leak (i broke off a nipple when removing the heater core and didn't notice)

since the IACV is a solenoid it closes when no voltage is applied, but when idling it opens to regulate the a/f mixture. when you have a leak it gets too much air so disconnecting it then turns your leak into the idle intake source.

I recomend just rerouting the coolant lines to the FIATV and blicking it off. more power, less variables going into idle problems.

mgags7

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmvtec7700 &raquo;</TD></TR><TR><TD CLASS="quote">I had this a while ago and just want to add the following.

Unplugging the IACV fixed my problem, however it was not bad. I had a vacuum leak (i broke off a nipple when removing the heater core and didn't notice)

since the IACV is a solenoid it closes when no voltage is applied, but when idling it opens to regulate the a/f mixture. when you have a leak it gets too much air so disconnecting it then turns your leak into the idle intake source.

I recomend just rerouting the coolant lines to the FIATV and blicking it off. more power, less variables going into idle problems.</TD></TR></TABLE>

Thanks for sharing your experience, but for most of us, blocking the FITV is a bad idea. I like my car to warm up quick in the winter.

hoo my gosh

good info

moparwrench

New to the world of Honda. Have a 97 prelude, 99,000 miles. Have the idle bounce and followed your very helpful instructions. No vacuum leaks, removed TB and cleaned. Cleaned and adjusted fast Idle and Idle Air. Bleed coolant more than once. Starts off a cold bounce, goes away when warms to temp but any load on alt. causes bounce also. Of course the load changes the idle air position, so I suspect IAC weak or bad but unsure of the cold bounce then load bounce. Any help in diagnosis would be deeply appreciated.

GYChris

wow GREAT thread. just fixed my idle surge. turned out to be the FITV

93sivtec

I found that the tool they give you to screw down the antenna works great for the fitv,its like a little 2 prong rake looking thing,but it fits perfect.If u have ever bought a new antenna mast or replacement antenna for any vehicle it usually comes with one.

Great write up.

Toe_Knee

Ok, I took off the intake tube. Plugged the top hole on the left. My idle surge/bounce went away. Does that mean I have a bad IACV? Where is that even located? Is it the thing in the front with the 2 coolant lines running through it?

h23prelude

i had this problem too, i only drive my prelude in the summer so i only recommend this if youre not worried about warm up times, because it will tale longer in the winter to warm up. all i did was make a small aluminum block off plate from some hardware sheet 1/16" thick aluminum. drilled three holes and used a Manila folder to make a gasket. i had a few shorter 10mm bolts sitting around, use the shorter ones because the other three are way too long. and install the plate with a SMALL amount of grey rtv and it works perfect for me. just remember to adjust your idle when youre done because it shot down to like 500 rpm ldle after i did it, then i adjusted it right back up, just my 2 cents

picture from under the throttle body-




Modified by h23prelude at 5:35 PM 2/11/2008

Toe_Knee

Today I went to check for the problem again and I found out that there was some sort of cabe by the firewall. It wasn't hooked onto the little shaft so I hooked it in and my idle problem went away. Don't know what it's called but its behind the TB near the firewall.

Little_Red_Lude

WOW !!!!! I must say thanks to everyone involved in this post !!!!!! I just bought a 91 Prelude with 220K miles and a blown clutch and this problem. I replaced the clutch and got the car running good except for the idle problem. I am a Chrysler/Jeep mechanic (and have been for 20 years). I spent 2 days trying to figure out this problem (bleeding the coolant, replaced the EACV, cleaning the throttle body, etc....) I finally broke down and took to our sister store, the Honda dealer. They called and told me it needed the FICV ($90 for the valve $200 labor). Needless to say I wasn't very happy. I came back to my shop and got on the internet and did a Google search for the FICV and came across Honda-tech, did a search, and no more that an hour later and $0 dollars my problem was fixed. You now have a new member who is greatful for the good advice. Let me know if anyone needs any Chrysler/Jeep help..... Sorry for being so long winded. Thanks again, Billy

mgags7

lol, good stuff billy, glad to help a local

BB1LOViN

does this apply to IDLE SURGE that only happens upon start up?
my car does the idle surge only when its a cold start.
once heated to full temp, the car idles perfectly normal.

Little_Red_Lude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BB1LOViN &raquo;</TD></TR><TR><TD CLASS="quote">does this apply to IDLE SURGE that only happens upon start up?
my car does the idle surge only when its a cold start.
once heated to full temp, the car idles perfectly normal.</TD></TR></TABLE>

"Make sure the coolant is topped off and there is no air pockets. If the coolant temp sensors dont have coolant around them it throws the computer off. " I was told ths by a Honda tech. Makes sense, but I dont know how true it is. I had a constant idle surge between 1000 and 2800 RPM all the time before the "FIX" now it is perfect.

mgags7

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BB1LOViN &raquo;</TD></TR><TR><TD CLASS="quote">does this apply to IDLE SURGE that only happens upon start up?
my car does the idle surge only when its a cold start.
once heated to full temp, the car idles perfectly normal.</TD></TR></TABLE>


Sounds to me like an FITV problem, I'd tighten it up some and see what happens.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Little_Red_Lude &raquo;</TD></TR><TR><TD CLASS="quote">

"Make sure the coolant is topped off and there is no air pockets. If the coolant temp sensors dont have coolant around them it throws the computer off. " I was told ths by a Honda tech. Makes sense, but I dont know how true it is. I had a constant idle surge between 1000 and 2800 RPM all the time before the "FIX" now it is perfect.</TD></TR></TABLE>

It is true. Air pockets around the sensors will throw the readings bigtime. The air in there will heat up very fast as compared to the coolant.

lilloui05

http://forums.ntpog.org/showthread.php?t=609

any ideas?

cliff notes:

replaced all intake manifold gaskets (including injector o rings, etc.)

blocked fitv
ive tried, known good map sensor, known good tps ...

bb4 jdm lude

thanks alot i will try this asap

sxm5369

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h23prelude &raquo;</TD></TR><TR><TD CLASS="quote"> i had this problem too, i only drive my prelude in the summer so i only recommend this if youre not worried about warm up times, because it will tale longer in the winter to warm up. all i did was make a small aluminum block off plate from some hardware sheet 1/16" thick aluminum. drilled three holes and used a Manila folder to make a gasket. i had a few shorter 10mm bolts sitting around, use the shorter ones because the other three are way too long. and install the plate with a SMALL amount of grey rtv and it works perfect for me. just remember to adjust your idle when youre done because it shot down to like 500 rpm ldle after i did it, then i adjusted it right back up, just my 2 cents

picture from under the throttle body-


Modified by h23prelude at 5:35 PM 2/11/2008</TD></TR></TABLE>


would it work to put gasket paper between the fitv and the trhottle body, and reroute th coolant lines?

vlang29

i would think so, i've heard of people using pop cans

MuddinPede

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mgags7 &raquo;</TD></TR><TR><TD CLASS="quote">6) Try bleeding your coolant system, I have yet to see this problem actually make a car idle bounce, but Gavzter below (thanks) added this suggestion so I suppose he has seen this problem before, either way it cannot hurt. Normally when a coolant system has air in it, it will just make the engine run slightly rough because it makes the water pump cavitate when the air gets down there.</TD></TR></TABLE>

I can vouch for that. When I was installing a new radiator on my 93 Civic Si, I left the cap off so I could bleed it as I filled it. When I started the car it started revving from 500rpm to 2000rpm. I added coolant until full and it stopped.

wildcat98

To bleed the coolant, first, make sure the car is cold, completely.
Take the radiator cap off, if you can fill it any, fill it almost completely to the brim.
Try squeezing the radiator hoses and moving them a bit without making all the coolant gush out of the open radiator, to try and work any air bubbles out, remember air will be at the highest point in the hose, so work it away from there. After that is done, top it off again, cap the radiator.
Start the car, and use a 12mm socket to open the bleeder nipple on the thermostat housing, it is located on the left side of the valve cover towards the back of the block. You may want to put a towel or rag there to catch the coolant as it sprays out.
Leave it open until the car is good and hot, and then wait for there to be a completely constant spray of coolant, that means all the air has worked its way out for now.
Let the car cool completely, when it is completely (I mean completely) cool again open the radiator back up, you will need to top off the coolant.
Done. Check it again a few hours after your next drive.




can u take a pic of the bleeder nipple

vlang29

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wildcat98 &raquo;</TD></TR><TR><TD CLASS="quote"> can u take a pic of the bleeder nipple </TD></TR></TABLE>

the bleeder nipple is on top of the thermostat housing. To find the thermostat housing, follow the lower radiator hose to the back of the engine, and where it meets aluminum again, that is the thermostat housing. You can't miss the nipple on top.

sxm5369

hey guys, i finally fixed my idle problem, after replacing the fitv, iacv, and tps, and nothing happening i took apart the intake manifold and it was one of the gaskets that was leaking and pulling air in. it looks like oil was getting in the intake from the line that goes from the valve cover to the intake, and the oil is what was wearing out the gasket. i replaced the gaskets and cleaned the egr, intake manifold, throttle body really good and now it runs perfect. hope this info can help someone

AJ06

good read

gstrudler

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sxm5369 &raquo;</TD></TR><TR><TD CLASS="quote">t looks like oil was getting in the intake from the line that goes from the valve cover to the intake, and the oil is what was wearing out the gasket. </TD></TR></TABLE>

Sounds like you should check your PCV (the small valve on the t-belt side of the valve cover that runs to the intake manifold). Either way it will get oil into the system I guess (hence catch cans), but I've heard that a clogged PCV will send that nasty stuff into your intake instead of straight to the IM...

gstrudler

Alright, now it's my turn to be plagued by this problem. I recently did a t-belt job, installed an electric water pump and pulled my IM. I put it all back together (finally) and now I've got an idle bounce I can't figure out.

I'm leaning towards air in the coolant as now my temp gauge is acting up, where it will show normal temp for a while then randomly go up to varying degrees (sometime pegged at the top) briefly but then settle back down to the normal temp. However, I have attempted to bleed the system several times, so I'm not 100% sure this is my problem anymore, but am still considering it a possibility and may end up trying a complete flush and fill again if necessary.

So here's what happens: I can turn the car on and sometimes it will start the idle bounce between 1200-1900 after a few seconds, but more often than not it will idle normal until I apply any kind of throttle. After I have applied throttle and let it return to idle, then it will begin to bounce. Tonight I pulled my intake to test the FITV; by blocking either of the ports on the TB, the bounce will go away and the RPM's will go down. The bounce will stay away even after I release the hole until I hit the throttle again; there is strong vacuum coming from both ports.

The other thing I saw after re-reading the tips at the top of the thread is possibly my throttle cable is too tight and is somehow keeping the TB plate open a little. I had tightened the cable after re-assembly, but there still appears to be a small amount of slack in it. But, it makes me wonder since I can plug either port on the TB and get it to stop (I'm assuming it creates more of a vacuum inside the IM, causing the TB to close tighter) and will idle fine until the throttle plate is actually opened again. Is my idle screw set too loose and letting air by? How would I check this?

Ideas? Insight? I'm pretty sure it's not a vacuum leak because it doesn't do it all the time and I made freaking sure all my gaskets were sealed up (after having to pull my IM a second time because I didn't seal it up well enough the first time). The car runs fine other than this issue.