yeah, I've pretty much noticed this since a little before I got the car, but when I go to start it up after it's been sitting a few hours, it'll start, and the RPMs will shoot up to where they are supposed to, but when they come back down, they don't stop at 750 or whatever idle is and keep dropping until they reach zero and the car dies... so I'll start it back up, and in order to keep the RPMs up, I'll rev the engine. but as soon as I let go of the gas they drop real low again, so I rev again. usually, once I rev it to ~6000 and let it come back down it'll idle fine and then run fine for the rest of my trip, and if I shut it off for a while and come back, it'll be fine. but if it sits for 6 hours-ish or more before I start it up again it'll do it again...

what could be causing this?

iac=IDLE AIR CONTROL VALVE

This post has been edited by LewFX: Oct 27, 2006 - 12:13 AM

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where exactly is that located? I thought it might be some kind of vacuum leak, but I don't know where to look for one. lol

This post has been edited by 6strngs: Oct 27, 2006 - 12:24 AM

http://www.lewfx.com/throt0.pdf

This post has been edited by LewFX: Oct 27, 2006 - 12:34 AM

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Thanks! that helps!

according to that though, that tube that runs from the valve cover to the throttle body is the PCV valve?! could that be a possible culprit as well? I kind of have mine set up in a weird way:


.............Throttle body
.......................^
Valve cover<---|--->Intake

This post has been edited by 6strngs: Oct 27, 2006 - 1:08 AM

ok, took my car to my auto class today. hooked it up to a smoke machine thing to find vacuum leaks. I don't see any leaks near the iac. I did however, find that my EGR valve is leaking

anyway, is there any other possible things it coule be? or, was I supposed to be checking the iac for something other than a leak? my teacher mentioned that it might have something to do with fuel pressure...

you have to have 2 hoses hooked to your intake piping between the turbo and the afm. one is for pcv and one is for the cars idle valve. make sure that one is hooked up and trace it all the way back to the throttle body to make sure there arent any cracks or air leaks along the way.

It could be a dirty throttle plate throwing the computer off. Have you cleaned it? Also the IAC motor and the EGR valve are common suspects.

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I don't have a turbo... unfortunately

in any case, the hose that connects from my valce cover (PCV?) to my intake is pretty new. The same hose is split so it can go to the nipple coming off the bottom of the throttle body (idle valve?). the stock hose when from the throttle body to the valve cover, but I split it to go to the intake too, since I thought I was supposed to(see this thread) also, the smoke machine didn't reveal any leaks from any hoses.

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so it could be the EGR valve? because the smoke test did show a pretty decent leak from my EGR.

my bad, i got you and 6gsillyca mixed up .

either way, there should still be a hose that goes from the intake to the throttle body on the 5sfe. if i remember correctly, it was on the bottom side of the intake, close to the throttle body.

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there is. I just have it split to go from the intake to throttle body AND the valve cover.

EDIT: nevermind, I do have another nipple on the intake that is on the bottom side very close to the throttle body. I have some hose connected to it, but I really don't know where that hose goes to.. (it goes down deep into the engine bay.)

This post has been edited by 6strngs: Oct 28, 2006 - 8:51 PM

its not a vacum leak at the IAC thats causing the cold start idle to be off. its likely carbon buildup inside the IAC passages. remove the throttle body, and disassemble the IAC from it. then clean out the carbon in both pieces with intake cleaner. the idle may act weird after you do this until the ECU relearns.

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is it possible to remove just the iac? or do I have to remove the entire throttle body?

just remove the throttle body, the iac is attached with screws that you really cant get to.

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*sigh* ok... but do I really have to drain the coolant to take it off? I didn't even know coolant went through the throttle body.

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what? no you dont.

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if you click on the link by LewFX in the third reply, in that thing, where it says how to remove the throttle body, it says to drain the coolant...

you dont have to drain the coolant. some will spill out, but just have a few rags handy. take it off when the engine is cold and you should have no problem.

ok, I never did come back to update. I took what I believed to be my iac off and cleaned it, stuck it all back together, and it still does it. in fact, it's been getting worse lately. this morning it didn't even start until I gave it gas (normally it starts and then dies right away, this time it didn't start at all) and it's been doing it more often. are there any other possible things it could be?

Are you throwing any codes?

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nope. No Check engine light at all.

alright, I tried figuring out what was going on a few minutes ago... well, I was checking for vacuum from my PCV valve (I think that's what it is... the little nipple sticking out the side of the valve cover) and when I pulled the hose off of it, it made a strange squeeking noise, and when I put my finger over it, I could tell it was blowing air out, but after removing my finger I saw that it left an oil residue on my finger. is that normal? I have this valve going into both my intake and that nipple sticking off the throttle body, for some reason I'm thinking that blowing oil into an intake would be a bad thing...

When I pulled off the throttle body to inspect the IAC, I did notice it was really dirty inside the throttle body and intake manifold... could this possibly be severly damaging my engine by blowing oil into the cylinders?

I wanna pull off my valve cover and see if I can get a better look as to what is going on. I've never done this before, is it hard? and does it need a new gasket when you put it back on? the only time I would really have time to do this would be tomorrow morning, but I doubt I could get a new gasket by tomorrow.

you need a new gasket if its leaking on the sides

alright, I'm gonna see what I can learn tomorrow. tonight, after playing some more, I took a small hose off of one thing on my throttle body, and it made my idle jump to about 1,800 rpms. So I drove my 5 miles to work like that, and then after work, I went back to my car, at this point it's been sitting for about 6 hours, and it's 11 o' clock and pretty cold outside, so I figure it would do the start and then die thing on me, but because I had removed that hose it didn't die on me. and after a good long search through my hayne's manual, I see something about an ISCV (idle speed control valve), now, when I was looking for this last time, I didn't find anything because I was looking for an IACV (idle air control valve) anyway, after reading though it, I think that what I cleaned before was not my ISCV, so I'm gonna rip my throttle body off again tomorrow and see if I can clean my actual ISCV and see if that fixes my problem... though I am still concerned about my PCV putting oil into my intake, and I'm wondering if that is what might've caused my ISCV to become overly dirty in the first place... anyone know more about any of this?

The thing you think is your PCV is the spot where you had a tube running to the original stock intake? Look on my profile you will see a red tubing line running almost straight from my intake to the top of my valve cover. You mean this< If so that is just a vent to the valve cover. That's all. It does need to be vented however there is supposed to be a baffle plate that keeps the oil splashed by the cams from running into that line. You would need to pull the valve cover to inspect it but I can't think of a single reason why there would be anything wrong with it. If you pull that tube you should hear a loud almost metal cricket chirping noise. That would be the normal sound of the valves that is otherwise inaudible because of the tube that runs it to the intake. I know cause when I first hooked up an intake to my car I did not run that tube I just put a k&n breather on there. As soon as I ran the line back to the intake it shut up. Kind of like when you put your finger over the nipple.

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yes, that red tube in your profile is going to the same nipple I was talking about. My car has an extra nipple on the throttle body, and after being on this site for a while, I notice that I'm not the only one that does. From stock, I had a tube that ran from the nipple on the side of the valve cover to the throttle body. then when I got my injen intake, I was trying to figure where everything went. I ended up splitting the hose so that it went to the intake and the throttle body.

anyway, I wasn't too worried about the noise, I just didn't know if it was normal. I am worried about the oil coming out though. I think I will have to pull my valve cover off and look. (quick question, does the oil need to be drained before you pull the valve cover off?) today, in just a few minutes, I'm going to pull my throttle body off again, and see if I can clean my iscv (for real this time, lol) I'll pull the valve cover off another day... I'm hanging out with my girlfriend tonight...

what I did yesterday, I bought a new hose which now runs from the valve cover vent to the throttle body (like stock) and I put a breather on the nipple on the side of my intake... but now I'm thinking I would probably be better off just plugging that hole instead...

tomorrow morning will be the ultimate test. if it starts without me having to rev it, then I was successful in my cleaning of the iscv. However, I never actually took the iscv off... I tried... but the four screws holding it on were really ****in tight! and in the process of trying to remove them, I stripped all the heads so I cleaned what I could using engine degreaser and Q-tips.... it really cleaned alot of crap out. and my car seems like it starts better. like, instead of the rpms jumping to 1500, then dropping to 4-500, then raising back up to 750, they start at like 1500, then raise to 2000, then slowly drop back down to 750, the way they should. But like I said, tomorrow will be the ultimate test.

Sounds like you got the right idea. hope it works out ok. you need to figure out why oil is coming up that line. maybe put the breather back on there - deal with the sound and look for oil coming out. That is def. not normal. I've removed mine several times in the last 3 years and i've never seen any trace of it there. As I said there is supposed to be a baffle plate there for this purpose and I can't think of anything that would have damaged it except maybe a careless mechanic. I assume by your questions that you have never pulled the valve cover.
I'll help you through all this anyway I can. Just hit me up. It's not hard to pull the valve cover but you gotta be careful, ie. not strip out stuff. Just take your time and make sure you are not damaging things in the removal of it.

yeah, I was about to declare that I had fixed the problem. the car started several times with no problems whatsoever, even after it was sitting for a while... but then last night after work it did it again... is there anyway to remove those four screws that I stripped the heads on?

If you do pull the valve cover off, then yes you have to replace the gasket.