car has trouble starting, what could it be? Options

[6strngs]

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?

[LewFX]

iac=IDLE AIR CONTROL VALVE

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

[6strngs]

iac=IDLE AIR CONTROL VALVE

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

[LewFX]

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

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

[6strngs]

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

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

[6strngs]

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...

[lagos]

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.

[toyotacrazy]

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.

[6strngs]

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.

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.

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.

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

[lagos]

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.

[6strngs]

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.

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

[cheeco]

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.

[6strngs]

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.

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

[cheeco]

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

[6strngs]

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

*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.

[hitcachi]

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

*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.

what? no you dont.

[6strngs]

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

*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.

what? no you dont.

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...

[cheeco]

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.

[6strngs]

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?

[hitcachi]

Are you throwing any codes?