Cleaning the Idle Speed Control Valve (ISCV)

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Read this guide through completely before commencing to ensure that you are competent in doing the work yourself. By following this guide you are accepting full responsibility and I will not be held

responsible, directly or indirectly, for any damage or anything else caused by following this guide.


12mm Spanner

12mm Socket

Extension for socket

Beefy pliers

Carby Cleaner

10 or so cotton buds


Car Key

Impact screwdriver

IACV Gasket (part number: 22215-7A680) Replace if swollen and wont fit.

Throttle Body Gasket (part number: 22271-88600) won't be needed, but up to you.

Screw driver

Saftey Eyewear Can be sunnies, glasses anything that protects your eyes.


1a. Refer to the disclaimer at the top of this guide. Ensure the engine is cold. Start by unplugging the two sensors on the throttle body. The sensor at the front (green circle) is the ISCV and the sensor at the back (green circle) is the throttle position sensor; be sure to not pull on the wire. Pull the throttle wide open so that the throttle cable is slack; remove the end of the cable (yellow circle). With the 12mm spanner undo the blue circled nut; it will need to be undone completely to get the cable free.

1b. If you haven't done the throttle body coolant bypass you will need to refer to this workshop guide for what needs to be done regarding the two coolant hoses that lead to the ISCV.



2. With the screw driver undo the hose clamp on theintake pipe that goes between the throttle body ad the air box. Use the beefy pliers to open the hose clamp on the hose with the pink circle and remove this hose.


3. Using the 12mm socket with extension remove the two nuts at the top of the throttle body and the two bolts at the bottom. The bracket for holding the throttle cable will also come loose at this step.

4. Remove the throttle body from the car and place it on it's back. Underneath is the ISCV that needs to be removed (red circled). For this step you must use an impact screwdriver. Strip the heads and it is not my fault. Don't balance the throttle body on the hose barb (from where the pink circle is) when using the impact screwdriver as I assume it isn't fun replacing the hose barb. Some blocks of wood either side of the hose barb work a treat.


5. Once the ISCV is free take it back to your car and conduct a test. Put the key in the ignition and turned all the way without starting; go back to the plug for the ISCV and plug it in and listen for movement or feel vibration within the unit. It will move very fast and is very quiet. If it moves you can either put everything back together, or clean it. If it doesn't move clean it!

6. With the tin of carby cleaner spray it into the two chambers of the ISCV. The crap built up will be caked on really well so use the cotton buds to get in and give it a good scrub. You can also plug it into the car again as per the above step with a bit of carby cleaner inside as it moves; don't rely on this to clean the shaft! If you like you can clean the chambers on the throttle body itself as there will also be a build up in there too.


7. Replace the gasket and put back together. I gave the impact screws two-three wacks and gave them a quick test with a screw driver to ensure they were done up.

8. Installation is reverse of above steps.

Hopefully that covers what needs to be done.

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Might be a stupid question, but whats the benfit in doing this?

When i do a carby clean i wipe the throttle flap and spray the crap out of the inside of the throttle body with carby clean and then start the car and rev it, just wanted to know what this was for/does?

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Great write up mate well done.

though cant see how this would be necessary for a car less than 5 or 7 years old... Unless heavy amount of ks and huge driveing. Maybe on 12 - 15 + years, common task on the 4age 20valves.

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heres how dirty mine was after 140,XXXkms





partly cleaned


tried to remove the 3 screws on the ISCV and snapped off the tip of my screw driver... -_-

then i went to toyota for them to take it out and they took 2 out but the 3rd one they rounded off! :o


so i went to parts and they said that the screws arent available anymore!

omg what do i do? bolt specialist should have the same bolt and pattern right? :(


edit: went to conventary specialist and got replacement bolts with a 8mm hex head so i can easily remove it in the future...



they didn't give me any washers to suit but i think it should be alright. i'll get some washers hopefully tomorrow if they have some. make sure they are high tensile ones

some of you will inevitiably round the screws off so this is the next best thing

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Howsit buddy..

do you have any pics of it once you cleaned it fully?

if you do.. do post them for us to see...

Thanks! :)

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Howsit buddy..

do you have any pics of it once you cleaned it fully?

if you do.. do post them for us to see...

Thanks! :)

it just looks very shiny! lol :lol:

also i wanted to note. i did reset my ecu and found that when going into neutral (warm engine), my engine does idle a little higher than before (around 1.2k then drops to ~900rpm, whereas before it was between 900 and 700 rough idle). Will the ECU relearn it quickly or have i done something wrong? i'm guessing its all the extra air going thru the throttle body as its cleaner? also i found that my sticky acellerator pedal still happen even after i cleaned the TB :(

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great DIY SD! very sexy throttle response now :) i couldn't get eveything out the ISCV. sprayed the crap outta it with carby cleaner but still no go :(

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Thanks for the great guide. Not sure when I will need to do this though.

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Yeah, really a good DIY.

Question, did you have any symptoms while driving that made you clean it? Or it was just to keep it clean?



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This seems to be a complicated issue which a new friend at the dealership thinks is software related rather than parts.

I have a 2003 Pontiac Vibe GT with 2ZZGE engine. This past weekend I cleaned the throttle body and IACV (idle air control valve). I did a complete throttle body removal and also removed the IACV from the throttle body. Everything went perfectly and was cleaned to new condition.

Exactly what I did:

PROBLEM: when I performed the clean I made sure to disconnect the negative terminal and I was disconnected for at least 4 hours (I was also replacing the oil pan gasket). When I finally started the car it idled at 2000 rpm. Once I actually drove it and then clutched to return to idle or put it in neutral the idle was 3000 rpm and a quick gas pedal flick would cause it to drop down and begin an idle search where it surges the rpm from 1500 - 2100. Sometimes this doesn't stop till I put it in gear and drive again or sometimes it finds idle at about 2000 rpm. I can also tell that while the vehicle is driving that there is throttle without my foot on the pedal.

I spoke with my new dealer friend and pulled my EFI fuse and relay for 1 hour with no change, so I left my car overnight with the EFI fuse pulled and still no change. I confirmed that when the surging is going on, that the throttle butterfly is fully closed and not moving. This means that the IACV is indeed working and is what's causing the surge. Like I said, the IACV is mechanically moving but it refuses to relearn proper idle.

The only thing I can find that is pretty much exactly what's going on with my car is this video were a guy has an MG that surges just like mine and he does a manual idle relearn through a pedal press/ignition on/off coded process. I've asked the dealership if there is a manual idle relearn override and they've advised that it's supposed to automatically relearn idle after ECM or EFI was not powered for at least 1 hour.

MG video:

Just to be clear:
Throttle body is perfectly clean and butterfly is not restricted or not closing
TPS (throttle position sensor) was not adjusted or changed in anyway during cleaning
No engine codes or engine lights are present
Throttle cable is fine and tension is good

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