yes ive searched already but nothing seems to answer my questions...car is a 94 civic ex...

here are the symptoms:
-car idles high for cold start (which im guessing is supposed to happen)
-once car is warmed up, idle purges (but dont really remember to what rpm though)


ive already tried cleaning the screens of the iacv and screwed in that plastic thing on the fitv.. and car still does the same thing...


ive read somewhere online about taking off the intake and looking at the two holes in the throttle body, and heres what ive read:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Make sure your car is completely warmed up. With it running, take the intake off the TB. There are 2 holes right in front of the throttle plate, these are the holes that feed the IACV (top hole) and the FITV (bottom hole). With your finger, cover up the bottom hole (it should NOT be sucking if your car is warmed up). If the idle goes down the FITV is to blame, either get a new one or take it apart and screw the valve completely closed (I have only read of people doing this, so I don't know exactly how. Also, you will have to keep the engine speed up yourself when the car is cold).

Next cover both holes up with your fingers. The car should sputter and die (or almost die). If it does then the source of your crappy idle is the IACV. Replace it. If you want you can test the IACV. Shut the car off and put + battery voltage to the blk/yel terminal (on the valve) and momentarily touch ground to the blu/yel side. When doing this the valve should click, if it doesn't, replace it.

If, when covering both holes the car still has a high idle, you have a vacuum leak somewhere. Again check the IM and TB nuts. You can spray carb cleaner around those areas and if any gets sucked in (the engine will rev) you have found your leak. Another source of vacuum leaks are where the FITV and IACV connect to the IM. Either replace the gaskets or use silicone gasket sealant. </TD></TR></TABLE>


ok... when i cover the bottom hole, the purging stops... so that means a bad fitv, but theres still a vacuum going on (its still sucking) but in the writeup, it says that it shouldnt...

and when i cover both holes, the car dies... writeup says that if it dies its the iacv...

so im still unclear about the above things... and is it BOTH of them that are bad...??

 

Hey Cuda.
I am Running a 92 Honda Civ with a ITR Intake:
I am getting the same issue that you are getting. Here is the storie.

when the car is cold im getting about 3,000 to 3,500 rpms. And when its warm the idle changes from 800 - 2500 rpms. So i have changed out my IACV for a known good one... no change. Made sure all the vacume hoses are connected, checked for leaks... nothing their.

No what im planning on checking next is the FITV, i have not checked it yet. I was wondering if you had ever fixed the issue. Due to are issue sounds similar... let me know.

thanks rob

 

bump bump bump keep this post up i am having the same issues. got a new tps,throttlebody, and map sensor which solved power loss but now iu have power surges and when i start the car up it idles at 2000rms for a while then goes away. its frustrating!

 

As you say, the outcome of your test with the lower hole clearly suggests that the FIV is bad because you should not have felt any air flow/vacuum from that TB hole when the engine is warm.

The service manual, however, recommends a different test for the IACV. Without removal of the intake from the throttle body, disconnecting the IACV connector should reduce the idle speed if the IACV is good:

 

I would check the Throttle Body mounting gasket and the intake manifold gasket for vacuum leaks. These are common leaks as well as the obvious vacuum hoses.

 

well i have been having the same issue, And after some troubleshooting i found that it was my FITV. After letting my car warm to operating temperatures. I pluged the hole to the FITV and the car dropped from 2000 rpms and idles steady at 800 or so rpm. So at least that was my issue. If you go to http://www.dc425.org/myhonda i have some trouble shooting information that i have found off this website and other sites on the web.

rob

 

while the car is running disconnect the iacv and if there's no change the iacv it pry bad. also if you think you have a vaccum leak spray carb cleaner around your vaccum lines at small spots at a time and if the motor revs up you have found your vacccum leak. I would say iacv or vaccum leak for sure.

 

unplus the iacv or remove it completely. i know when i unplugged TPS it started to idle higher than 2k i cut the car off before i found out what it went to

 

possible culprits:

1. vaccuum leak-throttle body gasket, intake mani gasket, or open vaccuum port on manifold. Try putting your hand over the throttle body while its running, if it still runs you got a leak, or even if it runs longer than a second before dying you have a small leak.

2. related to 1. brake booster 1 way valve. or leaking brake booster.

3. IACV- could be wired incorrectly or stuck open slightly. Sometimes they do just go bad, it is a sensor. Try tapping it with a small ballpein hammer while the problem is occuring and see if it makes a difference.

4. FITV- You said you did the fix

5. Low coolant level, air in cooling system.

6. Timing, has to be really f'd up

7. throttle body valve sticking open slightly and/or throttle cable too tight.

8. Bad PCV valve

9. TPS sensor, will throw CEL

10. Idle air adjustment screw backed out too far.

That's my top ten and all i can think of right now. The wrong ecu could potetially cause erratic idle too. My bet...low coolant or vaccuum leak.

 

mine does the same thing, I can make it go away by messing with the amount of load being drawn on the electrical system... like once it starts to fluctuate I can turn on my fans and lights at the same time right while the engine is surging down and it will hold at normal idle. does that mean anything?

I tried most of all the other **** and it didnt work so I just gave up.... now I dont even remember what I checked and what I didnt. by now it has followed me through 3 hondas, and I just accept it when it happens. Oh also for some reason mine got a lot better when I did a TB bypass.