knoxrocks222

ok heres the deal, i have a 95 civic cx with a mini me swap, the idle is perfect when i first crank it, after the engine warms up it starts reving up and down up and down up and down, you can put a stop watch to it. it goes from i guess 600 rpms to about 2000 rpms...no tach, i took the fast idle valve off the other night and it was tightly screwed down, i gave it a good cleaning anyway, then i stuck my finger over the hole in the tb for the iac valve and it almost sucked my finger into it at idle when warm, so im guessing its stuck wide open, i stuck my finger over the hole and it just kept huntin idle, iv probably put a hole in the ozone layer over my house spraying so much carb cleaner THERE ARE NO VACUME LEAKS ANYWHERE, and MY COOLANT HAS NO AIR IN IT just so were clear haha im not spending 200 dollars on a new iac valve either, is there a way to block it off and put a small hole in the butterfly in the tb to regulate the amount of air going into the engine at idle??? or is there a way to completely disable this all together and just set the idle screw

im so tired of people staring at me at the light cause they think im sitting there reving my engine at them.......oh yeah and on a funny note the original owner of the car knew about this problem and thought it would be cool to stick a fart can on the back to ampify the reving so people could really hear it and stare at you

apexi_rsx

maybe make a fast idle valve block off plate or buy one off ebay. i did this myself it just takes longer for the car to warm up in the winter.

HondaPartsHero

i would also check for any vacuum leaks as well. Do you have access to a known working IACV or could you get one from the junkyard to test?

shoal007

he stated this occurs when car is hot. Fast idle works when car is cold. This is IACV, PCV or vacuum leak. I bought a used IACV on ebay when I had similar problems -- cleaned the crap out of it and still had problems. Spent the big money on a new one, and all problems went away. sometimes you gotta pony up.

joeshmo

Had similar symptoms with a leaking IACV gasket (causing a vacuum leak). Replaced gasket, problem went away.

knoxrocks222

I went back and checked for vacuum leaks...nada If I block off the iac it will be fine in the winter my garage is heated Im going to look for a block off plate I'm pretty sure the iac is the culprit due to the extreme sucking from that little bypass hole in the tb at idle thanks for the quick replys

Former User

CEL codes?

Is the coolant low in either the reservoir or radiator? Have you bled the cooling system?

Have you tried to adjust the idle speed as detailed in the service manual (see FAQs sticky)?

Have you tested the ECT sensor or TPS?

knoxrocks222

Air in the coolant would not affect the iac just so were clear, also as stated in giant letters in my original post there is no air in my coolant and both the radiator and over flow are filled to spec, and there are no vacuum leaks, no check engine lights as if now

I'm going to break out the voltage meter tonight and check tps

Thanks guys and gals if anyone else has any input feel free to post it up

Former User

Just so we're absolutely clear, this^ is absolutely incorrect.

If you unplug the IACV, does the idle speed drop?

apexi_rsx

and i second that yes air bubbles in the coolant can cause hot spots as the air will be hotter then the coolant. this will make the idle bounce from false readings.

T_ypEr

Definitely bleed the coolant. That's where I would start. From there, clean the Throttle Body, Idle Air Control Valve, and take a look at the Throttle Body gasket too. I had this same problem on my old 2000 CR-V. Turns out the ******** that cleaned my TB messed with the idle speed. So check your idle speed, too.

knoxrocks222

Just so I'm crystal clear the iac is an electronically controlled device, coolant plays no role in the operation of this divice, coolant is only fed into said device to keep it from freezing in the winter however coolant does operate the fast idle valve which Is not the device in question here

I'll re bleed the coolant again but I'm pretty sure there's no air in it

knoxrocks222

And yes Ron when I unplug the iac the idle drops and goes crazy and my car dies and the cel comes on

knoxrocks222

Fixed.... Base idle was set way to high, thanks everyone mods locker her down

Former User

Stop spouting false information and instead do some homework. You are correct that coolant flow through the IACV only serves to keep it from freezing up during the winter. However, what you completely fail to understand is that coolant temperature is one of the most important factors in controlling idle speed. Do you know why your engine idles high when cold and low when hot? It's because the coolant temperature (ECT) sensor sends its temperature signals to the ECU which, in turn, uses the information to control how much air the IACV bypasses from the throttle body to the intake manifold. Having air bubbles in the cooling system interferes with the ability of the ECT sensor to read the correct coolant temperature, resulting in abnormal ECU control of the IACV and idle speed problems. Your lack of understanding about idle control should now be crystal clear to you.

knoxrocks222

home work was done *** hat straight from the god damn honda service manual

The IAC valve is supplied heated water, via two small coolant hoses, to keep the valve from developing ice during cold operation. The IAC valve is not sensitive to the temperature increase from the heated water. The position of the IAC valve's plunger is totally dependent upon the amount of time the ground is on, which is controlled by the ECM.

close this thread before me and mr 19,000 post get banned

T_ypEr

Yup, same thing with my old CR-V.

Former User

Being a man of small brain, you fail to see that your statements are contradictory. The amount of ground that the ECU supplies to the IACV is in large part controlled by the temperature of the coolant. However, basic logical thinking escapes you, so I wouldn't expect you to grasp a simple concept like this one.

Don't come to this forum to argue about basic technical concepts that you clearly don't understand.