ISC, IAC VALVE

[jasonvibe]

The idle speed control valve(ISC) and Idle air control(IAC) as some call it are interchangable terms. So my question: Does the ISC control the idle ALL the time...or just at restart and cold start till it's warmed up???? Meaning once warm the ISC does nothing till restart? I am still trouble shooting my poor idle in cold temps. AND is there a safe way of cleaning it w/o removing it from the throttle body??? thanks in advance.

[wallyuwl]

You might just need to clean it. I cleaned mine when I replaced the intake manifold gasket since I had the throttle body off anyway. It is supposed to spin freely, and mine did not spin freely at all before cleaning it (just sprayed it good with some throttle body cleaner once it was all apart). Pretty easy once you realize what you need to do. There are two sets of screws, one is a six point star pattern. Don't try to screw these out, take a small pair of vice grip pliers. They are crappy screws, so I replaced them with 7mm (I think) head small bolts. I also replaced all three gaskets: the small funny shaped gasket in there by the valve, the round gasket (you'll know it when you see it - I put in a thicker one and the original was bad because it wouldn't hold its shape), plus the main throttle body gasket by the intake. Getting the right parts was easy because I took the whole ICV assembly with me into Car Quest. It would have been hard to get the right round gasket and small bolts if I hadn't done this.From your other posts you're more mechanically inclined than I am. not counting a possible trip to the auto parts store to make sure you get the right size stuff, I'd bet you could do the whole thing (including removing and replacing the throttle body) in an hour and a half.

[jasonvibe]

Since I was not getting replies....I did spray mine out. Using gumout and MAF cleaner and my compressor. But I did not remove ISC valve from the throttle body because of the ODD "funny" o-ring gasket ...I think only available from the dealer. Also those funky small screws at the end of the shaft were another thing. So they were not removed Yes, a bunch of black stuff came out on my "catch rag".... You say the small screws are 6 point. They looked 5 point to me and not torx So I was hoping I could find the proper bit to fit. My car seems to run more properly now since the cleaning I did. As the idle does change with whether the A/C is on or engine fan is running. But sometimes it idles not so smooth. Gettting "tremmors" thru the seat. And when the tremmors are there...they are there for the every stop. Then you restart the car...and they are gone till the ride is done. It's nothing consistant as of late. Other times it's so smooth...you hardly know it's running. Can I get the special ODD oring gasket that goes between the throttle body and ISC from someone other than the dealer? Also, DOES this "ISC valve" control the idle even when there is NO unusual load at idle, aka, A/C on etc. ??? Also, Wally, were you having idle issues before?

[Salsa Guy]

Have you tried running seafoam through it?

[jasonvibe]

Seafoam thru the ISC valve? YOu know the ISC is only an air valve below the throttle... No fuel in there. I have used seafoam on a few things. It has never really impressed me.

[wallyuwl]

No I wasn't having idle issues before, per se. But I did notice a difference after cleaning it. I got my o ring gasket from Car Quest. It isnt OEM size, but they have a whole bunch of them in a kit and we found one that fits in diameter. The one I got is thicker than the OEM, which I actually prefer. It was like fifty cents. I also got the new bolts from Car Quest. They were great. It was very helpful to bring in the whole ICV assembly detatched from the main throttle body (those screws came out OK).Yeah, I don't remember for sure how many points the crappy screws were. I just know they weren't torx, and they were crappy so I replaced them for like another dollar in two bolts and washers (they didn't have short enough bolts that fit the diameter). A vice grip pliers gets them off very easily. Then the ICV assembly opens up, and there is another small funny shaped gasket. I replaced that as well (I ordered a Felpro replacement ahead of time from Rock Auto for like $2 - Car Quest probably would have that, too, though it looked good to reuse if I wouldn't have bought another one).I'd take it all apart and use something stronger than the MAF cleaner. Throttle body cleaner or even brake cleaner.

[jasonvibe]

I did use "Gumout concentrate". Then flushed that with MAF and compressed air....which leaves no residue. That funny one I have seen in pictures ...Is like two or three "long" ovals attached at a common center.This seals the coolant . Is this the one you got from Felpro? If yes, Do have the part # available?

[cptnsolo77]

I have been wanting to clean the IAC for about two years, but I couldnt figure out what type of bolt heads they were. No wonder torx didnt work for me. Anyone have parts numbers for the O- ring and gasket?

[wallyuwl]

Here are the gaskets for the throttle body. The first two are what you need (both the Felpro ones). The first one is for between the throttle body and the intake. The second one is very small, and is for the IAC. http://shop.advanceautoparts.c...asketcptnsolo - The gaskets are above. I just got an o-ring from Car Quest. I don't have the dimensions or a part number. I just brought the whole IAC assembly in and we found on that worked.

[jasonvibe]

I already changed the throttle body one.Yes the first one for IAC seems to be the one. 61128."TBI base gasket". Other than that...you say an O-ring (you call a gasket) is needed once you remove the electrical end cap...Yes?

[wallyuwl]

I don't remember exactly where the o ring is needed. I'd have to go out and look. There is only one. I think it was for right by the IAC valve itself, that connects a circular metal piece with another part of the IAC assembly (note: this is all after you remove the IAC assembly from the main part of the throttle body). Really it isn't a big deal. Just go into an auto parts store (NAPA or Care Quest are probably preferred because they are less busy and usually more helpful than others) with the whole IAC assembly and they'll help you out. The IAC assembly removes from the main part of the throttle body using two phillips screws, if I remember correctly. The crappy/funny screws connect two parts of the IAC assembly together. Once you get the throttle body off it is all very simple to figure out. The hardest part is those funny screws, but those are very easy to remove using a small set of vice grip pliers. I highly recommend not reusing those screws, and intead getting different (read: stronger) machine screws or bolts (like I said I had to use a few washers on each one because Car Quest didn't have short enough bolts in the right diameter and thread, but it works).

[jasonvibe]

I will order the 61128 gasket. And I have many o-rings and machine screws in my vast collection. But also many auto and hardware stores near-by. Like I said, my car has days it runs like a gem at idle. Then other times it gives a buzz thru the seat...even after fully warmed up and the tach reads as it should. But the odd fact I still sometimes have the "buzz" thru the seat has me searching for answers. I even borrowed a very good scan tool to show my exact idle after my "quick clean" of the ISC. Idle was the proper 710rpm no load, after fullly warmed up. I am sure my winter isssue was random sticking of the ISC/IAC valve. And thus, it was slow to open up to allow "idle up" when I hit the brakes when a bit cold. The manual says this ISC is used to provide "idle up" and "target idle when needed." . This is my families only car. So I am careful with all it's needs. And do it all myself. I did a valve clearance check and other work on it too this year. Yes, I am mechanically inclined. Just very careful. AKA slow. thanks...

[wallyuwl]

Good luck. You will probably notice an improvement with doing it taking the whole thing apart vs. what you've done so far. Have you changed the VVTi "oil filter"? It is a little (like inche and a half long) screen secured by a 14mm bolt by the alternator sort of, just to the left of the intake manifold.

[jasonvibe]

I have heard about and seen pics of the VVTI filter. But what I had heard is it affects the GT engines the most because it moves a shaft that enables the intake valves, 1 vs 2. On the 1ZZ it advances the cam...I believe. .... I change my Mobil1 every 3 to 4k. How much dirt can be in there? Can the VVTI valve affect the idle on the 1zz engine ?

[wallyuwl]

My VVTi filter was in pretty good shape and not gunked up, but I've seen some that were not like this. It is a $6 part and takes about twenty minutes to change (took me five min. to get the bolt loose, 14mm, and ten to get the old one out using a tweezers - it doesn't just fall out). Not a bad idea to change it every 100k miles.

[biodieselrabbit]

Some pictures from when I cleaned out my throttle body and IACV today that I think speaks to this forum.

Throttle body removed from intake manifold.

IACV 001.jpg (24.72 KiB) Viewed 38379 times

Bottom of throttle body showing IACV (Intake Air Control Valve). Right side is where coolant lines enter (facing the rear of the vehicle) and left side is the electronic part of the IACV.

IACV 002.jpg (21.42 KiB) Viewed 38379 times

Special star screws that attach the electronic part of the throttle body to the aluminum part. I used vice grips to remove them.

IACV 003.jpg (19.92 KiB) Viewed 38379 times

[biodieselrabbit]

IACV after removing from throttle body.

IACV 005.jpg (19.41 KiB) Viewed 38378 times

Bottom of throttle body where IACV connects. Notice the red "crustiness" around the IACV gasket. I think this is coolant leaking through to the air side.

IACV 006.jpg (21.9 KiB) Viewed 38378 times

IACV with electronic (black) part removed. Notice the tab on the end of the round magnet (far right). This should be at the top of its turn when you reinstall so that it fits into a slot in the electronic part of the IACV. Also notice how black it is inside the IACV.

IACV 007.jpg (19.42 KiB) Viewed 38378 times

[biodieselrabbit]

The o-ring people have been referencing. Couldn't find a new one so I just reused it. See again the tab I was talking about in my last picture.

IACV 008.jpg (20.77 KiB) Viewed 38378 times

IACV after being cleaned. This took lots of throttle body cleaner and cotton swabs. Even after a long time spraying and rubbing it, I could not get the deep inside completely clear of blackness.

IACV 010.jpg (34.36 KiB) Viewed 38378 times

New IACV to throttle body gasket installed (Toyota Part # 22215-0D110). See the white scales in the left port of the IACV where the coolant runs? It looks to be corrosion, possibly caused by the previously mentioned leaking IACV gasket. Not sure though.

IACV 012.jpg (27.18 KiB) Viewed 38378 times

[biodieselrabbit]

Cleaned throttle body.

IACV 013.jpg (24.61 KiB) Viewed 38377 times

Reattached IACV.

IACV 014.jpg (24.29 KiB) Viewed 38377 times

While I was at it ,I replaced the funky star-patterned screws that go from the electronic to metal parts of IACV with socket head cap screws. This way if I ever take it off again I won't have to force them out with pliers.

IACV 015.jpg (27.03 KiB) Viewed 38377 times

[runnerpaul]

Thanks for posting these pictures, they have been a great help!

[bogdanas]

Hi, could anyone post the size of that O-ring and dimensions for IAC screws?