IAC Valve Help

[austin.c]

My IACV is acting up. I saw there are 2 coolant hoses and i wasnt sure if those could possibly be swapped? My idle is really low, like 800rpm, when cold, and when it gets up to opperation temp, the idle is 1500rpm or more.
It seems like something is backwords to me. It use to be I would shut the car off once warm and high idle, and when i started it again, still warm, the idle would be normal again. any help please? I already used the search, but i dont want to have to replace the thing.
http://newcelica.org/forums/showthread.php?t=131585&highlight=IAC

[MidnightMac]

The coolant hoses being switched would not have anything to do with how the ECU controls the actual stepper motor. The hoses shouldn't be in the wrong spot if you haven't removed the IACV. I actually don't really see how you could mix the hoses up...

Have you removed/cleaned/inspected the throttle body and IACV?
How many miles on the engine?

Here are the idle speeds from the repair manual (without cooling fan on):
Manual GT-S: 800rpm

[2way]

I don't think the orientation of the hoses even matters. It just flows coolant thru the IACV to warm it.

Have you cleaned the MAF?

[austin.c]

Maf has been cleaned. I have yet to try and clean the throttle body or iac. That's next

[MidnightMac]

People have had success with cleaning their IAC and having better idle.

However some have been forced to get a new one after cleaning didn't do the trick.

Also remember to reset ECU so it can relearn idle after you clean.

Good luck

[gorckat]

If you do remove it and clean it, I highly recommend replacing the phillps screws attaching the IACV with appropriate hex head screws. It'll be way easier to reassemble and easier to service in the future if the need arises.

[Cyrus]

I'm having the exact same prob on my auto gt. cleaned maf and cleaned TB and sprayed carb cleaner into the little hole that goes into the IACV till it fills up with it. still did not solve the problem..

at cold start idles at around 800-900 rpm and when warm it stays idle at 1500 rpm.. its driving me nuts :(

however my intake manifold have been replaced after a accident. so not sure if the mechanic didn't do a good job or if he swapped the coolant lines.

I would like to know too if the coolant lines were swapped will have this sort of problem. if not then next step i think should be replacing the IACV :(

[austin.c]

it seems the coolant lines dont matter, after reading others post, and looking closer at the pic. to do a complete clean out of the IAC it will prob need removed, and since we just got a lot of cold weather here, its gonna be a while.
Another comment i forgot is I just put a 3in ram air intake, and it took the stock ecu 3 starts to learn to richen up the fuel mixture. could this cause any problems too? but i still had this issue with the stock air box too.

[2way]

Another comment i forgot is I just put a 3in ram air intake, and it took the stock ecu 3 starts to learn to richen up the fuel mixture. could this cause any problems too?Yep, if the MAF is reading incorrectly or you have a vacuum hose open. 3" is oversized and the MAF will read incorrectly.

[austin.c]

Yep, if the MAF is reading incorrectly or you have a vacuum hose open. 3" is oversized and the MAF will read incorrectly.

Ya, i thought that it would read incorrectly, but my air/fuel runs like stock. it isnt lean... could the computer compensate for the difference?
And i could possibly have a vacuum hose lose, any help on that one? maybe diagrams or similar? links to other posts works too, thanks!

[Cyrus]

it might pay to check your coolant level and check if you have any air in your system.. i saw mine and noticed it was really low so i went and bought the Super long life coolant from toyota dealer and filled it up and bleed most of the air out..

after wards i noticed my idle was lower but it wasn't stable.. then i reset the ecu and let it idle for about 15 mins or so.. now when warm the car idles at around 1100 to 1200 rpm.. well it didn't fix the prob totally but i'll be bleeding it the proper way when i have more time to get the remaining air out. hope it'll fix it.

[2way]

could the computer compensate for the difference?Yes, via the fuel trims.

http://www.newcelica.org/photopost/data/500/thumbs/scan1.jpg (http://www.newcelica.org/photopost/showphoto.php?photo=27330)

[Seven-Of-Nine]

If you do remove it and clean it, I highly recommend replacing the phillps screws attaching the IACV with appropriate hex head screws. It'll be way easier to reassemble and easier to service in the future if the need arises.

+1 they were a bitch to remove almost had to try and drill them out, saying that those two grubscrew holding in the butterfly valve those are fecking bitches to take out gonna have to drill mine then reverse tap or use inserts tap up next size. I really do hate Toyota for using **** screws where the ends round off.

[MidnightMac]

sprayed carb cleaner into the little hole that goes into the IACV till it fills up with it. still did not solve the problem..


You must remove the IACV entirely to clean it properly and thoroughly. Also replace the screws with corresponding metric hex head bolts as suggested.