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How to: Clean a Zetec IAC

104K views 94 replies 37 participants last post by  amc49 
#1 ·
This thread is to help everyone with that nasty idle problem with higher mileage Zetecs.

Tools needed:
2 Jack stands
1 Jack]
flat head screw driver
8mm socket with ratchet
(1/4 inch is recommended, 1/2 inch is hard to use in tight spaces)
Carb/Choke Cleaner (semi large can depends on how much buildup there is)


Step 1: raise and support focus with jack stands


Step 2: get your flat head screw driver and take off the intake tube on the throttle body so you can gain access to the IAC when you take it off from underneath


Step 3: get under the car with your 8mm socket ratchet and start feeling up in behind the starter on the intake manifold there should be two bolts loosen them up and then take them out with your hand, they are easy to take out. The IAC Looks like this on the intake manifold, the silver cylinder looking thing.



here is a pic of the IAC location from under the car you can tell its really hidden away





Step 4: once the IAC bolts are out it should be sitting in there because of the tight space, it wont fall out because there is a wire connected to it. get back on topside of the car and grab this wire that my index finger is pointing/laying on and that is the wire you can use to pull the IAC out..

dont jerk manuver the IAC around from atop so that it can easily be pulled out.


Step 5: grab your carb cleaner and go to town on inside of the IAC valve




BEFORE






AFTER






Step 6: let the IAC valve dry in the sun or just air dry until no cleaner comes out of it. then reinstall!

Hope this helps everyone that has this problem! [thumb]
 
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#29 ·
I'm in the middle of doing this. Anyone know if the factory didn't use a gasket ? I used a small mirror to look at the intake manifold and there is no evidence there was ever a gasket there. The is nothing at all on the valve. I have some material to make one. So I'll do that. Also, how many times do I have to spray the inside of the valve ? I've done it three times and there's still some carbon in there.
 
#30 ·
Terry,
Absolutely put a gasket on. I removed the factory IAC and there was no gasket on 2002 Zetec. I was surprised. When I replaced without a gasket=major air leaks. Had to re-do the whole thing and fabricated a gasket from NAPA gasket material.

Clean it out till its squeaky clean. Might take a a good part of a can of carb cleaner.
 
#31 ·
That's exactly what I did. More time putting it back on than taking it off. I had the battery disconnected so I'll have to let it cycle through. It idled high on startup as expected. Then a few hours later it didn't want to idle at all. I haven't let it run more than a few minutes. I know that's not sufficient.
 
#32 ·
I don't know what's happening now. I went to move the car last night. I soon as the key was in the "run" position, the engine cooling fans came on. The car would not idle at all when started. I went for a 2 minutes ride around the block. When I put the car in park it idles at 800-900 RPM. After the battery disconnect, it should idle high for at least 20 miles. I just tried the car this morning and it barely idled at all. When I kick the throttle, it stalls on decelaration. The fans kicked on again after the 3rd or 4th stall. I disconnected the battery and I'll let it sit for a while and see what happens. All I touched was the IACV to try and clean it.
No codes shown or codes pending. Hasn't been run long enough to cycle. It's as if the car didn't reset itself at all.
 
#33 ·
Kinda sounds like the IAC has stopped working , after you take the battery cable off and let everything reset. When you put the cable back on it should have a high idle at start up until it gets to normal operating temperature then drop down where it needs to .
 
#34 ·
That's what it did on initial startup after the battery was reconnected iacv reinstalled. 4 hrs later and again this morning it wouldn't run at startup worth a damn. I just went for a 3-4 mile drive and it ran and idled okay. It was warmed up by then though. Although it's running about 200-300 lower RPM than ever before. I don't have the time today to take the iacv out. It took forever yesterday with those damn bolts and location. I would have just left the battery alone in the first place, but I hit the starter with my ratchet and scared the crap out of me when it sparked.
 
#35 ·
I disconnected the battery again and it won't reset. Goes right to low idle and stalls out if I don't keep my foot in it. It took a few minutes to get going for work this morning. Same thing when I left work. I'm getting a Delphi IACV delivered tomorrow. Exhaust is popping like crazy on decel and the exhaust smells. Not rotten eggs, I have no cat. The exhaust tone has changed also. It had a nice deep tone ( Borla catback ) Now it just sounds ratty.
 
#36 ·
@xecutionr (OP): Thank you VERY much for posting this thread last year! I appreciate it heavily.

My short story:
I have been running through my own preventative maintenance checklist, and the IAC valve was on it.
However: I have never known where the actual IAC valve was on the Zetec engine. Nor what it looked like (exactly).
Thanks to this thread: I now know! And especially thanks to my_beautious_ZX3 for uploading (high-quality!) photographs of it.

I will quite potentially upload a short video demonstrating the removal, and installation of the IAC valve now, and include a short picture tutorial.
But for now: I have only taken before, and after pictures of my own IAC valve (cleaned with Throttle Body cleaner).

Here they are!!
- BEFORE: http://imgur.com/a/wY9G5#0
- AFTER: http://imgur.com/a/gEQ16#0

Thanks again! The idle feels surprisingly different. Not substantially, but definitely noticeable.
 
#42 ·
I don't hesitate to take that coating off and never had any corrosion issues ever............been doing it for years on metal TBs. Maybe the cleaner there was suspect, a strong alkali soap would produce that effect and quick. I use acetone and I guarantee the coating is gone almost instantly.
 
#43 ·
just an update I forgot i deleted that photo bucket account and i no longer have the pics.. I'm sorry everyone. plus i no longer own my focus…

thanks guys [drummer]
 
#44 ·
Diggin this up from the dead... I removed my IAC and it looked like there wasnt a paper gasket on there as someone mentioned previously on this thread. Looks like 2 rubber O rings maybe and some liquid/flexible gasket maker type stuff. So my question is do I need to make a gakset or go buy one from the dealer? Also is there a way to test to make sure the IAC is even good before I put it back in since its a pain to get out. When I plug it in and turn the car on I dont see the plunger inside do anything but stay open about 1/16".

Getting it out was easy using a ratcheting closed 8mm wrench and a mirror to help with the top bolt. Getting it back on I know will be a PIA!!!!
 
#46 ·
Also is there a way to test to make sure the IAC is even good before I put it back in since its a pain to get out. When I plug it in and turn the car on I dont see the plunger inside do anything but stay open about 1/16".
that's the $64,000 question.

I've never seen any test suggestions on this forum. It's not an on/off valve, so the conventional test of applying 12v won't reveal much. Many of us just grab TB cleaner + a handful of Qtips, clean the living hell out of it, and then cross our fingers.
 
#45 ·
I found the answer for the gasket and it looks like whoever installed my motor half assed it and just made a gasket with some silicone stuff! I found the part number and pic for the actual OEM gasket. "Motorcraft CG-756 Idle Control Valve Gasket"

Still need to know how to test the IAC while off the manifold.
 
#49 ·
When mine took a shit it just refused to idle at all, it would start, and immediately stall. To limp it home I had to keep my foot on the pedal to keep the engine at idle speeds when sitting. I cleaned mine meticulously, and it worked for a while, but it came back. Replaced it with a new one, never had a problem. On the gasket note, mine never had a fiber gasket, it used two o rings to seal. The new valve came with a fiber gasket, which I did not install, sealed just fine on the o rings.
 
#51 · (Edited)
You risk a serious leak by not using a gasket, the old rubber seal often is hard and having been flattened and then cooked into that shape it will NOT properly rebound to seal again. Or, asking for trouble there. Why the paper gasket is supplied, cheaper and if you leave the rubber double o-ring seal in place the paper easily seals that. Silicone by itself could too if put on competently but you see the problem there.......... You can make one up for like 50 cents from gasket material, I make all mine. Make the holes intentionally a little small to where the bolts have to screw in and you even have bolt holders to hold bolts in place while you reinstall part. I always install with top bolt missing and bottom in place, get threads well started and then part held well enough the top bolt goes in easy. Five minute max job there. On and off in ten.

If you get solvent/carb cleaner in the vacuum diaphragm that is in some of these you can kiss part goodbye. Diaphragm is located at the rolled press seam, why part has to have a vent breather on it if it has one. Depending on where the idle air is available, the IAC may not move at all at idle and could be fine. It is when the unknowing move things like throttle plate stop and other things to make the idle air different when IAC is older and carboned up shaft that the problems begin. The valve cannot move easily against shaft deposits when they are heavy and any change you make requiring a big change in distance then screws you. Why you never mess with butterfly setting even though one is there.
 
#56 ·
Read higher up what I said about the possible rubber diaphragm in one, if so you just ruined it.

And why would somebody link to a page with most of the information gone, as in pics?

Counterproductive.
 
#57 ·
Ok, I read the whole thread, and although various YouTube vids said clean the throttle body as well as the IACV, I didn't see anything about that here. Should I try to clean the TB as well, or leave it alone?

amc49, that diaphragm you mentioned, is that on the IACV or on the throttle body?

I have some gasket material, I'll make a gasket for it. The gasket material I have almost looks like shoe-box cardboard, but more fibrous. Do I need to coat the gasket with something, or just put it in dry?
 
#58 ·
Dry works fine. TB if never been cleaned needs it too but careful not to get solvent inside the TPS cavity, best to remove the switch and solvent may distort the seal behind it, if you have time then the VOCs will evap out of the seal to let it come back to correct shape. I actually have cleaned TB before without even removing it, I wipe both the edges of butterfly and the exact area where the butterfly touches the TB outer body. Simply open it up and wipe with a solvent like acetone. The main area concerned with there is the exact aircrack formed where the butterfly closes to be almost dead shut, that slight crack you see there. Carbon buildup there blocks off the airflow needed past that crack, it is a needed part of idle airflow along with PCV and IAC flow.

IAC?

http://www.msextra.com/forums/viewtopic.php?f=101&t=55625

Got past the two pics to the 3 part line drawing next, the middle pic there. They show the diaphragm at the rolled seam where the aluminum body meets the actual solenoid case. Note the vent/filter sticking up, if IAC has that vent sticking up then it has the rubber diaphragm inside, if no vent then it does not.
 
#59 ·
Great, that's what I needed. If my IAC does have a rubber diaphragm, how do I avoid getting cleaner on it when I spray it inside the holes? Do I have to just use a q-tip to clean in the one nearest the seam?

If I understand all of this correctly, cleaning the IAC and inside the TB with a rag, just the edges of the flaps and the flaps themselves, could solve the problem. If it doesn't, it could still be the IAC, but I'll have to put in a new one to find out.
 
#60 ·
I normally use acetone as the solvent and then in a small glass jar with level poured to be below the IAC diaphragm/solenoid location and let it soak for a while. Then hold part with diaphragm up while brushing part ports clean. Then to make sure I don't install part for several hours to let any solvent exposure dry out of the rubber, with acetone that's pretty quick.
 
#61 · (Edited)
Well, bugger.

I got under the car today, found the AIC, couldn't get it out, Couldn't get the wrench on the top bolt. (Or screw? Whatever it is, couldn't get it out.) Got onto the bottom one once, just to make the initial partial turn to start to loosen, then never managed to get back on it again. It barely moved, so I don't think it was loosened enough to be a problem, which is good, because I was unable to re-tighten it.

I think if I could get access to a lift so could stand under it and get a better angle to reach in, I could get it.

I still don't know if this is the problem, but I suspect it is. I'm thinking of ordering the part and seeing how much a local mechanic will charge to install it for me.

Looking at the pics, I thought I could do it, no problem, but good grief, Charlie Brown, what a PITA.

my_beautious_ZX3, I respectfully disagree, the pics are important. Without them, I'd have had no idea where to grope around to find it. As I did have pics to help me locate it, I found it, saw it, and still couldn't get the damn thing out. [?|]
 
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