What is the location of the Idle Air Control (IAC) Valve

A HUGE Thanks for the GREAT suggestion for temporarily blocking the Throttle Body opening! I've done a very cursory check for vacuum leaks (hose condition and connection checking, etc)with nothing apparent at the surface, SO this blocking of the TB will get me more and better info.

HOWever. If possible.I'm still in need of knowing the exact location for the IAC valve on a 1990 Geo Prizm. The part I showed above IS indicated as being an Air Control Valve; however as described earlier, because it has no moving internal parts (that I can tell) I don't believe it is the IAC valve I'm lookin for(?).

Anyone have "hands on" :-) or other direct experience with the 1990 Prizm or even a good engine parts diagram for this prizm

this seems to be such an unusual car for anyone or any reference source to know anything specific about (outside of a dealer setting, which I need to avoid for the moment for financial reasons ). None of the engine parts seem to be in the usual or somewhat expected standardized location. Or it may just be me and my inexperience :-)

Anyways. Thank you (again) Saturntech9 for your super speedy and fantastic response and to all those who have or may be reading this.I DO appreciate your time spent. :-)

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Wednesday, May 30th, 2012 AT 5:20 PM

A thousand (sincere) thank yous for hanging in here with me saturntech9, (its ABSOLUTELY awesome of you, as a matter of fact :-)

to the best of my knowledge this Geo Prizm is the. BASE. Model.(Exterior trim and door piller is black) VIN Engine Code 6. DOHC 1.6 Liter engine.4AE-FE (?).4 door sedan.



For hoots.I've included a pic of the engine compartment :-) and I WILL reply a couple of more times with just a pic of different angles. This is like a big scavenger/treasure hunt without clear clues :-D

Image (Click to make bigger)

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Wednesday, May 30th, 2012 AT 11:42 PM

Here is a pic with a view from the front. But from ABOVE and looking BEHIND the area of the Throttle Body.

(throttle body to the far right of the pic. Engine block/radiator would be toward the bottom of pic)

A view looking from the right(passenger)side of vehicle into the area BEHIND the throttle body assembly.(Intake? Manifold?)

And last one.

A closer view looking from the right(passenger)side of vehicle into the area BEHIND the throttle body assembly.(Intake? Manifold?)

Yup.I'm fairly certain I'd be able to find the part in a store or online and can you estimate what size this part is? (And you betcha they are quite expensive. Yikes?) However before I'd put out the monies to replace.I'd like to

1. Take a crack at cleaning the interior moving part of that valve.(As I understand can be done) to see if that'll have a positive affect on the high idle. Then. If it doesn't.

2. Do a further deeper check for a vacuum leak. As you've described. Probably do this at the same time and if there is no vacuum leak, the hoses and everything else connected checks out (egr valve. PCV, etc) o.K.

3. Then, as a last resort(?) I'd have to probably replace the whole IAC valve (ugh!). But I've also "heard" that within that IAC valve, there is a smallish motor that is replaceable for waaay cheaper; but I'd have to assess the advantage and overall sense of doing that as opposed to just changing the whole #@% ! Thing :-)

***********
So (yeah!) You said earlier that you think you see the IAC valve on the left hand side (I'm assuming while looking from the front of the vehicle. That would actually be on the passenger side of the intake?)

I know what that part is supposed to look like (and definitely thanks for confirming with YOUR pic) but sadly I still can't see it on my %@# car :-D.(Please refer to the very first pic I attached. The part I'm holding in my hand.

Then look to the forth (4th) pic I posted of a view looking from the right(passenger)side of vehicle into the area BEHIND the throttle body assembly.(Intake? Manifold?). On the left side of the intake manifold you can see that part (I was holding in my hand) with the blue color electrical connector is that what you're thinking you're seeing is the IAC valve?

If it is NOT, then could you please give me a little landmark (such as: go directly across from the oil filler cap OR going from the firewall go to backside of the intake manifold and above, below to the right or left, etc of the rather large diameter vacuum hose, etc etc.I wish we could circle the pic location. Where's john madden and the telestrator when we need it :-D)

Anyways, I've rambled on enough. You are an amazing person for dealing with "this" with such patience. Its gotta be hard to have to try and diagnose something "strange" from far away like this.

If for nothing else. We will have been making this "thread" for those who are having the same type of issues with this same #%*&@ vehicle, but either couldn't find the proper location/engine diagram of the part on their own or they're too ("shy"?) To ask the question. :-)

have a Good Night Saturntech9 :-)

STAND BY. :-D

yikes and yuck I'm bogged down at work so haven't had a chance to check. But I'm thinking you got it located right (and the theory of the IAC SHOULD put it right next to or UNDER the throttle body). Only problem is. Is that it is (might be) under the TB.

For a QUICK look, while I'm here at work; I'll have to get a little mirror to squeeze through the openings and look under the TB without removing anything that is currently in the way.

I'll DEFINITELY keep you posted. We're in this together saturntech9 :-)

:-)

BINGO! That's it!

With a broken piece of mirror I was able to confirm that you nailed the location! [Woo hoo!]

(O' don't worry, I broke the mirror on purpose which invalidates the curse. Has to be broken by a careless accident to get the 7 years of bad luck: at least, I hope so. :-D)

Anyways :-). From the photo YOU provided of the part; it is mounted upside down on the bottom of the throttle body.(It'd be nice if car manufacturers didn't have to put stuff in such an inaccessible place. EGADS. That's gonna be a pain to dismount :-D]

now the last and only question to figure out is:

there is NO visible sign of an electrical connector ANYWHERE on the valve housing as I imagined would then go to the idle air control motor (as I've attached a parts picture below).

Could it be that such a motor is internal. Within that IAC Valve (once it is removed from the bottom of the TB)?

OR

does the guts of that valve. Does this vehicle even have or need such a motor?

Is it just a simple mechanical. Air/vacuum propelled. Component that moves as the air is passively drawn in or out, etc etc?

OR

is the IAC motor (as picture below) somewhere else on the intake manifold? (I would kind of think not, since it should all be working together in close proximity. Attached?).I'm going out to look at one LAST spot on the intake manifold. We're really SUPER close to the end of the original intent/need of the question.

I'll keep you informed. Prolly tomorrow-ish. :-D

YOU DID AWESOME! (Or as the kids say today.) YOU ROCK! :-D
this is kind of a Fun little treasure hunt and I get to get dirty. So yippee :-)

Have a GREAT evening saturntech9. Chat with ya later. :-)

Whaaaat? You mean I’m NOT the only one in your life that your spending time on? WELLLLLL! Of all the nerve! :-D (and here I thought I was special and not just because I rode in a short yellow bus) :-D

I appreciate the “check in” from you... But I never lost faith that you ’d be back here whenever you could...I kind of figured hoped :-D you had a life outside of just staring at your computer monitor reading my rambling messages :- )

Speaking of rambling: here's more.

The truly annoying thing about this vehicle is that it is almost like the designers were experimenting with the newer computerized technology that was JUST starting to be imagined (and would-sadly-become a standardized design for the later years) while still keeping some of the old mechanical elements intact... And they seemed to have mixed and MASHED both type of components all together into this vehicle and probably other ones too, during this early 90’s era...(Some parts in this car just don’t make sense as to why they’re here when coupled with basically electronic/computerized components, too)

But anywhooo...I’ve come across a couple of things as I’ve been surfing the web; trying to come up with some answers for US :-D

1) I found a more close up pic of the underside of THAT part YOU found for me and as I zoomed in I could see something of a spring /screw type “drive” system inside AND I came across a youtube vid of some other vehicle (totally different make model, etc think it was like a Silverado Pick up or Jeep or the like) and the type of IAC they were showing was similar... With no electrical connection.

But in order to repair it the person in the vid... Had to remove the brass end cap... And inside was a flattened plastic looking disc with a couple of slots cut across it and by placing a flat head screw driver in one of the slots he rotated the disc till it was wound back downward again... Essentially he seemed to be resetting the? To its most effective (or original) level... Don’t Know IF this is what WE got inside of our valve or it’s something else entirely...

AND

2)I also found (by accident) a geo metro forum which seemed to show in one of its threads, an IAC valve, that looks amazingly like the VERY first pic I posted above in this long thread and their thread went on to describe how they gently pulled back some of the SMALL metal hasps that were surrounding the top... And removed the top housing where those hose connectors were and revealed a type of piston inside see the pics I attached below with this one)

Sooo I’ll do a little bit of “on car’ investigation this weekend to re-look at that component I posted a pic of first above (but prolly not much else in regards to removing the TB and getting a good clear visual on OUR IAC valve, cuz I won’t have access to getting a TB replacement gasket should I find I need one after my gorilla attempts to remove the TB... Just to be on the safe side) AND, of course I’ll definitely keep thinking about this, looking and reading also...

Since you've got waay more experience, expertise AND resources I'll definitely look forward to what you've been able to discover. BUT. BUT. Please know only as you're life allows and at your convenience. This isn't a "hair on fire type of emergency", its turned more into an annoying, but fun(?) Type of obsessive challenge.

HAVE A FANTABULOUS WEEKEND Saturntech9. Rest well (when ya can) and play often.

Chat with ya later and thanks again for ALL of your thoughts and efforts.

[the following pics are from that Geo metro forum for comparison]

2)

Well Shoot Howdy, I’ll be dipped in sugar and fed on by ants:-D

That’s absolutely PERFECT!...I’d have to say we ARE there... :-D

You Were a bit busy reading this weekend, Uh? VERY Nice! (Very, VERY much appreciated, too :- )

in combination with what I was able to discover this weekend... It looks like we’ve got this pretty much corralled and almost branded... :-D...I love it when the pieces of a puzzle start coming together and the truest picture is revealed... :- )

I’m fairly certain now... After reading the descriptions you posted... That the “Auxiliary Air Valve” (which is located UNDER the throttle body) is NOT the culprit to the high idle issues... It does NOT seem as if it could really fail in this manner. Just by its very function, it seems like it has got a fairly limited and straight forward function (essentially just reading the temperature of the coolant � with no real moving parts or regulatory function; per se)

SOOOOOO... As I mentioned in my previous post on Friday... Even though I was only able to spend a few moments under the hood this weekend and I was able to confirm that, apparently, this “mystery part” I alluded to on Friday (and in my VERY first picture post above) is exactly what we were looking at from that “metro forum;” YOUR post on Saturday from the Mitchells site (which I was just able to see this afternoon)... OFFICIALLY verified (THANKS TO YOU!) That this “mystery part” is no longer a mystery; but is in fact a vacuum switching valve OR Idle Speed Control... Located on the far end away from the throttle body... And is akin to the type of idle air control “motor”-like part we were searching for...[Essentially mystery solved. BIG sigh of relief]

Now that a “suspect” has been identified; the kind of fun part begins: gotta find a new replacement part to be on the “safe side”...(I’ll do other testing to make sure the integrity of the vacuum system, hoses etc as well as the electrical connection is still sound... But from what I can see and hear already I’m sure this part is the ONLY culprit... Besides it’s over 20 years, even IF I do find something else contributing to the high idle... Which I now seriously doubt will happen... Thanks again to your posting of the “mechanical theory”. It should be replaced anyways :- )

I’ve already tried to “surf” the internet... Looking for THAT part (besides my getting swamped at work that’s another reason why I’m late in replying here)... But so far I have had no joy. When I put in the phrasing : 1990 corolla or Geo prizm along with any combination of terms: Idle Vacuum switching Valve or just plain Vacuum switching valve or Idle Speed Valve... None of the parts that “Come up” under those headings look EXACTLY like the one I’ve got currently on my car... So I wonder will I have to somehow utilize a modified. Re-configured part? (Yikes I may have to go to the dealer parts dept :-O... But even “They” might not have access to that exact part anymore?)...

So Any thoughts or ideas you might have on the right terminology and/or a link to where I could find the part... Would put a nice little bow on this package... And of course :- )

Even IF we had not been able to fully identify the location of the part... You still would’ve done AN EXTRAORDINARILLY WONDERFUL JOB! SOOOO WONDERFUL, by the way; that I’ve already started court proceedings to have one of my kids RE-NAMED: Saturntech9... In honor of you and your never failing efforts to stay at my side and help solve this “mystery”...(Of course within the house we’ll just call him “Satch9” for short, but out in public and in school... He’ll proudly be known as..... Saturntech9...)

:-D

Sleep Well Saturntech9... Have a Tremendously Terrific Tuesday and I’ll look forward to keeping you updated and chatting with you again real soon. Be good TO yourself as you are clearly doing for others. You deserve it. :-)