I'm throwing an engine code for my IACV and I just replaced it recently as it has been acting up for a while and the car still won't run correctly nor does the engine code dissappear. I replaced it with a brand new one and I have no idea why it shouldn't run fine now.

 

Did u reset the ECU?

If not inplug the battery for 20 mins. That will reset it.

 

I unplugged the battery to reset the ECU yes, but not for very long. Few seconds at most.

 

Well go do it for about 20 mins. Thats about what the manual calls for to reset the ECU.

That might work, but IDK.

 

Does your idle go up when you turn the AC on. Wait till the engine is fully warmed, do you also get a higher idle when cold and the idle comes down as the engine warms up.

 

On idle it has surges between 1000 and 2000 rpms. I have the opening in the throttle body plugged to bypass the IACV so it idles normal. But on cold start up it is horrible to start. Very tough to start

 

That thing you have pluged up. I think that if you unplug it it will stop serging. This sounds all to familar to me. What type of motor do you have?

 

why'd you bypass your IACV? u want to bypass the FITV.. without the IACV aren't you in constant launch mode? (no response until 3k RPM)

 

High Idle speed and Fluctuation troubleshooting

Leaking EACV- Disconnect EACV connector. Idle speed should decrease. With the connector disconnected block the hole in the intake port or pinch the hose from the air cleaner to the EACV. If the idle speed decreases the valve is leaking. This condition will not set a code. The ECM can only detect an open or short circuit. It also may clog it’s screen if it has one.

Leaking IAC- (Idle air control valve) Disconnect IAC connector. Idle speed should decrease. With the connector disconnected, block the hole or pinch the hose to the IAC valve. If the idle speed decreases the valve is leaking. May not set a code and may not be a codeable circuit on all models.

TW or ECT sensor- (engine coolant temperature sensor) voltage should be about 3.0 volts @ 60 deg F and between .55 & .7 volts @ normal operating temp. If the voltage is above .8 volts at normal operating temp, will cause rich mixture and high idle speed. May not set a code because it is not far enough out of its operating parameters. **Also this sensor will not read temperature correctly if coolant is low. (beware)

Vacuum leaks- a loose vacuum hose or leaking intake manifold gasket can cause high idle speed and/or fluctuation. Also check for bad PCV valve.

Fast Idle Valve- (if equipped) a fast idle valve that is sticking can cause high idle speed and fluctuation. Check it by removing the steel cap on the top and putting your finger over the hole in the middle of the seat under the cap or block the port just inside of the throttle body opening, when the Idle is fluctuating or staying high. When the engine is warm this valve should be closed. You can tighten the seat but it will also change the idle speed warm up values (closing).

Throttle valve- throttle position sensor voltage should be .5 volts with the throttle closed. Make sure the throttle valve is fully closed and voltage is within spec.

ECU-If all else is good, if you reset the ECU and the problem goes away temporarily, the ECU may be defective.

Verify that the cooling system is full of coolant and
there is no air in it.

Remove the air boot from the throttle body and cover the
throttle body with something that will stop the airflow
(your hand, tape) with the engine running. With the
throttle body covered and no air going into the engine, the
engine should stall. If the engine does not stall, look for
a vacuum leak. With the engine running and the coolant
temperature above 90 degrees F, verify that there is no
vacuum on the lower port in the throttle body. If it does
not lose vacuum, look for a faulty fast idle valve on the
bottom of the throttle body, as long as the coolant hose is
good and hot.

Verify that the base idle screw was not turned way out on
the top of the throttle body. If it was, set the base idle
and see if the problem still occurs.

The upper port in front of the throttle plates feeds the
Idle Air Control (IAC) valve and the base idle screw. If
the IAC is unplugged and the base idle screw is turned all
the way in and there is still airflow through the upper
port, check for a stuck open IAC valve.

 

Great reply "Duane"!! Bump!

 

i have this same problem too my car is cold it pulses between 1-3 k once its warm it stop SOMETIMES i did get check engine for 14 which is the IACV i cleaned it reset the bat and nore more check engine sometimes when i have the AC it pulses stop also

i have tried some of these methods already accept 3 pf these methods i just want a little more detail on it becaus i dont quit understand or know where these connectors are... sorry for the questionm

Leaking EACV
^where is this connector?

Leaking IAC- (Idle air control valve) Disconnect IAC connector
^where is this connector

Fast Idle Valve
^Steal cap? and the whole?
^ is t his the whole inside the IM where there are two holes and i block the bottom hole?

and i dont understand the last one about the IACV

 

simple. take the fitv off an make a block plate. disconact all coolant lines. then clean iacv.

i want to yank my iacv..i dont need it right?

 

wait is this a reply to yingyang or me

and sorry ying yang if i jacked your thread

 

it can be used for both. You can dis bale the FITV on all hondas. Its been said to give extra HP since its not warming the TB. I don't think so so much. but it will eliminate some factors of screwy idle. i made a thread a while back on this same thing. i just completely removed the FITV an made a block off plate. never had a idle issue.

 

ok well ill keep this in mind is there anyone else that has done this? i mean is that ok for a h22 or prelude in general i guess

 

FICV is for cold fast idle only, the IACV (IAC) is for idle control the rest of the time and you should not take it off but I have seen it removed and the engine will surge. Do some searching for pics or buy a Haynes manual, there is stuff all over this forum.

 

you've only seen it surged it the block off plate has a leak. I removed about 10 of these on all different cars. Mines off right now. 01 prelude.

 

mgags suggested the same thing to me, gasketpaper = blockoff plate.. should work like a charm. if theres a leak then perhaps liquid gasket to seal it off.. but shouldn't be neccessary

 

Where is the EACV? this is the code that im throwing, but my friends have never heard of it. we assumed its the same thing as an IACV.

 

Different cars with different engines use different idle devices, do you have any kind of repair manual on hand.

 

yes and i checked it....it doesnt have much for troubleshooting. I have an IACV. And i was working on it last night and i found and fixed a vacuum leak. it helped a little bit anyways.

 

vacuum leak to the IACV? those are coolant lines.. if it helped.. go bleed your coolant system and get rid of the bubbles.

 

Honda is a speed / density system (MAP) and all cars do not like unmeasured air getting into the intake, everything must go past the MAP and any leak internal or external will affect this car.

An internal leak is too much air than what is expected by the computer, idle screw open too far, throttle blade out of adjustment, IAC acting up, FICV leaking internally, bypassing too much air and so on.

 

no it was just an unconnected hose on the the back of my intake manifold, not on the IACV. I don't have much time to work on it but since the IACV is brand new im gonna look at the FIV when i get a chance.

 

im pretty sure its the fast idle valve since the lower port in the throttle body is what has vacuum and when plugged stops the surging, but would that valve make the computer send the IACV fault code, is it in the same circuit?