My iacv has been acting up i cleaned it and replaced it with a new one. But still no success. It ran good for a couple days and idled good also then today it started acting up again. So i pulled over and the idle was around 400 so i unplugged the iacv and nothing happened the idle stayed the same then i plugged it back in and it started working again. the idle went up 1000 so i shut the car off reset the ecu or ecm whatever it is by pulling the backup fuse. Then i waited started the car and the iacv quit working again so i just drove it home and parked it for now. Any help would be appriated

 

i had this problem. first thing i would recommend is to get the car warmed up completely (rad fans come one at least twice) then once it is idling at about 750-850 unplug the IACV. one of two things will happen. 1. the idle will drop a couple hundred RPM. if so the IACV is working fine. 2. the idle stays the same. if this happens then the IACV is bad.

if your IACV is good then i would move to the FITV and take that off and clean it and check for it working.

Also if you replaced the IACV or took it off you introduced air into the coolant system and need to bleed the coolant system again. air bubbles can cause this problem as well.

 

Ive bled the system and also cleaned the fit valve. I put 2 different IAC valves on it and same thing on both. It will slowly leak as it warms up. It idles like 500 it ran good for a couple days then today it started acting up. It waz idleing at 750 then today i stopped at a light and noticed it was like 400. It stops working for some reason but if i unplug it the idleing dont change but when i plug it back in it works for a couple minutes then stops when i clear the CEL. I dont understand i thought i fixed this problem it was running good for a couple days now my problem is back

 

Set your base idle. There's more to it than simply watching it drop a couple hundred rpm.

 

The idle screw wont let me go past 500 no matter how far i turn it out

 

yea setting your base idle should be completed. in my experience if the throttle stop screw hasnt been adjusted the base idle is correct.

 

The girl i bought the car from had the idle screw all messed up so i turned it the whole way in and started over but it still took like 3 or 4 full turns to get it to 500rpm then it wont go any higher even if i keep turning the screw out. Also should i re-silicone the screw when done?

 

Possibly the air passageways for that idle-air-screw are dirty & restricted? Take the screw all the way out & clean it. Look for old crunchy O-rings. Clean & rejuvenate where you find problems.

I haven't sealed it with silicone, but you should judge that by how tight that screw is. You don't want it to move around as you drive over the next 2 years. I think there's a spring in there, maybe stretching the spring might make it tight enough. You have to be confident that it won't rattle & move & lose it's adjustment.

It's pretty common for misguided mechanics to fiddle with that thing; also to "adjust" the mechanical stop for the throttle plate itself. I've even heard of people using the throttle CABLE to adjust their idle RPM. When you don't understand how the idle-control system works, it's tempting to just "adjust your idle RPM".

 

i always read my shop manual before i do anything but what is the throttle stop screw your talking about cause i replaced a throttle cable a while back and the problem seemed to start after that idk if their related......maby i bumped it or something i made sure there was slack in it alittle. Today i got a tooth brush and cleaned my throttle body to make sure it closes the whole way but i didnt drive it yet

 

Look around the cable-drum where you attach the throttle cable. Should be some kind of stop-screw that physically stops the throttle shaft from turning. That thing should be adjusted so it just only prevents the throttle plate from wedging stuck closed. You want the actual throttle plate to pretty much completely close but you don't want it to wedge itself against the throttle bore & get stuck closed. The shop manual doesn't explain all this; it just says DON'T MESS WITH THE SCREW.

Then you want to adjust the cable so it goes a bit slack when your foot is not on the pedal. The cable should NEVER hold any tension when your foot is off the pedal. You can try to make as little slack as practical, but it has to go slack.

Was the throttle body dirty with black crud around where the throttle plate closes? If so, there might be similar crud inside the air passageways for the idle-screw, IAC, and/or FITV.

You said the system was adjusted funny before you bought the car, so I'm just over-explaining everything just in case there's something else messed up.