IAC valve or motor bad, whats the diff? - Honda Prelude Forum

belizeprelude · 12-22-2004, 04:30 PM

OK so my 93 si revs up and down on its own constantly (very annoying at the lights; kids think im challenging to race against their cavaller) and they told me it was the idle air control "module" when i go to discount auto they have only the idle air control "valve" and tell me that there is no "motor", so i bought it, took it to my mechanic, he tells me its a "motor" and i need a "valve" so he installed it anyways but it didnt work. So...what is the right part? i have the one that had two hoses connected and bolts to the outside of the trottle body. H23a1 engine btw...

Si_g · 12-23-2004, 07:36 PM

check out this thread, this guy had the same problem and. I m pretty sure that isyour problem. I posted on there to help, try it it should work.

HELP!!!! idle prob *vid*

but here is another post i made somewhere else.

My problem was the idle control valve, located inside a lil conpartment, attached to the bottom of the throttle body. my motor mounts were bad, which cause my engine to shake a lot, so that thing got really loose, so i opened it, and i fell out.

you can just remove the throttle body completely, take about 10 mins, then uncrew the back of it (2 little screws holdin a bronze plate, its facing the inside of the car on the bottom part of the body) and look inside. There should be a white plastic thing, with a spring around it thats your idle control valve. make sure its not all loose if it is ( mine completely fell out when i openned it so i put it back 2gether, and it was my problem), tighten it and screw it back inside of the body with a flat head, its simple, u ll know what to do with it when u see it, then put it back together. and fire it up. My was doin the exact same thing, i didnt bother with the finger test. i just did that in about 30 mins, and put some silicone around the gasket of the throttle body and slapped it back, and its been fine every since, been about a year now.
of course i changed my motor mounts b4 i did that, and i put it back 2gether, and idle has been perfect between 500 and 750.

I had the same problem and thats what i did to fix it.

g luck

92 SI Ludester · 12-23-2004, 08:34 PM

surging could be from a few things. check the basics first. vacum leaks, IAC, EGR, fuel pressure, coolant level. start with those and then see if you find anything with them wrong.

belizeprelude · 12-24-2004, 12:57 PM

ok thanks but does iac mean idle air control "motor" or "valve"

Specalk · 12-25-2004, 08:55 PM

make sure ur coolant lines to it are not blocked up, mine was doing the samething and even the honda technition did not know what was up so one day i just took it off and there was my problem, coolant line blocked.

marcucci · 12-28-2004, 08:55 AM

IACV refers to the "valve" which is what honda calls it. It happens to have a motor in it that drives a screw assy that allows more or less air to bypass the throttle body. Valve is more correct but when you are working with Autozone and some **** mechanic you probably are NEVER going to hear what Honda calls it.

Do a search here for idle, IACV, IAC valve, throttle body cleaning, etc, and you should find the source of your problem. Also make sure your coolant is topped off and there's no air in it. If your Fast Idle valve (near the IACV) or the thermal valve on the underside of the throttle body aren't hooked up right, or the coolant has air in it, you can get surging like you have.

delguiner · 12-29-2004, 06:29 AM

If your IACV doesnt fix the idle bouncing problem, i suggest to take a look at the FITV (Fast Idle Thermo Valve) which is located right under the throttle body!

vipastyle · 12-29-2004, 09:09 AM

Cross-refrence:

Idle Problem - Pulsing Idle

belizeprelude · 12-29-2004, 01:58 PM

thanks for the advice ill check that

red92si · 12-29-2004, 02:14 PM

I would assume that you have already adressed the easy-to-fix causes of bouncing idle already (ie: bubbles in cooling system, clogged IAC filter). It would be a shame to waste all this time and money when the problem could possibly be cured by something as simple as removing your radiator cap for 10 minutes.