Okay so like the title says sometimes on cold days after i drive for a little my idle will be very low lately it has actually started to die. Normally my idle is fine and sits solid at 750, it never does it on warm days and it doesn't always do it on cold days. Usually it goes away when the engine warms up but not always. I would think this is iacv related but i recently cleaned it. Does anyone have any ideas what could be causing this.

 

im having the same problem sometimes but im on a chipped ecu i thnk the duty cycle needs to be raised..

 

The IAC is the most likely problem, r u surfe u cleaned it good and properly??

 

Joel, did you already try adjusting the idle screw on the throttle body?

Another item to consider is a clogged PCV valve or PCV/breather hose .

 

well i didn't think adjusting the idle screw would help because normally it idles fine it seems like if i adjust the idle up it will be too high most the time. I doubt it is the pcv valve mine is not more than three months old. It is possible a hose could be clogged i guess... i will check that

 

For my OBDII Civics, I find that adjusting the idle screw to the highest point that still maintains the idle speed at spec yields the most steady idle under all conditions. At least for OBDII Civics, you seem to be able to turn the idle screw quite a bit before the idle speed changes, most likely due to the ECU's capacity to compensate under widely varying conditions.

 

hmm ill give it a shot...your talking about the screw on the tb not the adjustment in the iacv right

 

Yes, the screw on the throttle body. Does the IACV have an adjustment screw?

By the way, the idle adjustment procedure varies with engine type. You have an OBDII B16a2 engine and an OBDI ECU and throttle body (right?), so I am not sure whether you use the B16a2 procedure or the OBDI Civic procedure to adjust idle speed.

Also, have you already adjusted the ignition timing to spec using a timing gun?

 

same problem, random low idle. some of the times its normal, just cleaned IAC and whole throttle body. and replaced pcv..

 

the iacv has that nylon piece inside that can be screwed in and out to adjust cold engine idle...but you can't get to it unless you take the cover off. Yes the timing is set to spec. I would think i use the obdi procedure... but what is the exact procedure so I can make sure I am doing it right.

 

Isn't that the FITV?

 

oh yeah duh i meant the fitv btw do you know where i can get those manuals you used to have a link to in your sig

 

I PM'd you.

 

thanks i just downloaded them, hopefully i will have time to mess with this tomorrow. Today got kinda busy really quick. This kinda problem stinks cause you never know if you fixed it since it's so random.

 

well i checked today the idle is set exactly right when it is warm it idles at 450 with the iacv unplugged and then it goes up to 750 when the iacv is plugged in. I think i will try cleaning the iacv and fitv again and see if that does anything.

 

I turned the screw more like you said and it seems to be working...atleast today it was fine sat solid at 750. I think it just has to do with the colder weather.