Step By Step Instructions For Iacv(idle Air Control Valve)/isc/throttl

[snick]

Huge thanks for posting this, I have just successfully fired up my rx300.

The two screws in front of the IACV were a real pain to remove, but a vice grip fixed that.

I can get on with my life now! B)

[mathewd23]

Hi GoldenStateSilverSport, It is one of the best articles i have read and very detailed with the clear images. Hats off to you. I did not see this article earlier, but I just worked on my 2009 Lexus Rx300 with only 98K miles on it. I had to take the air filter box out, throttle body, intake manifold to remove the rear Valve Cover so i could change the spark plugs, VCG and the PCV replacement, I cleaned the throttle body with a towel to remove grease out but did not do the steps you just showed as I am totally a newbie. but now i think i will take the throttle out again and clean all the parts with the carb cleaner and see if that helps.

I have a question. When i drive on the highway at 65 miles and over i feel the car is not smooth and needs more gas to get it running, the moment i take the feet off the accelarator, it slows down, did not have this issue before i took the manifold out or the throttle body out, am i missing something out here. it drives ok when i am below 40.

Idling in Park is at around 800 RPM, but if i drive and stop at the stop light, it misfires. there is no CEL whatsoever to figure out if i have a bad ignition coil. Like i said i changed all 6 plugs with NGK Iradium. but when in drive mode and at a Traffic Light the RPM goes down to 400-500RPM and then i can see some vibration on my steering or something like misfire.

Any help from anyone to bring this car to its original state will be appreciated. my email is mathewd23@yahoo.com

Thanks

Matt

[B-Lex-Owner]

Thank you for your detailed post... And progress pictures.

[therainmann]

Hello, i am in the middle of this process on my 2001 toyota avalon. there was a brass wavy washer, and it is definetly not made of metal because it fell out. i asked autozone if they had a replacement and they were absoluetly no help. stating i dont even need to put a new one back in there. can someone please help me out here!

[Abhijit]

Hi everyone -

Thanks for the solution. I did manage to pull out the screws after a bit of effort and found that the idle valve was a bit stuck. So, was able to complete the cleaning. And to my delight for the next 15 mins, the car ran as if it was brand new. But now :( since yesterday evening, its returned back to how it was, the idle is still hard (a little better than before), yet the humming sound with the low RPM ( around 750 ) is still there.

Any suggestions on what I should look at? Im the second owner and the previous owner have kept it up to date with servicing, timing belt changes, transmission oil change. But it was more garaged and has about 81K miles on it.

Any clues on what I should be looking to clean / replace to get this idle smooth? Thanks for DIY instructions anyways. Very helpful indeed. Learnt a lot.

2002 Lexus RX 300 - 81K

[FrankE]

Yesterday our 2000 ES300 suddenly started stalling after startup and would not idle. I could keep it running with my foot on the accelerator though. I started my Internet research and came to the conclusion it was the IACV. I usually try to do my own maintenance to save money and frankly most times I think I do a better job. But I didn't really have time to dive into this project and tried a quick fix I saw on a YouTube where you just remove the air inlet hose from the throttle body to expose the small opening in the bottom of the inlet that leads to the IACV. You spray some carb cleaner down this opening and on the video, it fixed the problem right away. As much as I didn't want to try this quick and dirty approach, I did and it did not work.

I am normally reluctant to try removing assemblies with many screws, nuts and connectors in hard to reach places because I know at some point I'll reach one that is impossible to disconnect. Based on GSSilverSport's post, I decided to give it a try. Even while using well fitting Phillips heads and exerting a huge amount of downward force on the screw head and also using penetrating oil, I still managed to strip 2 screw heads. I ended up having to cut a large horizontal slot across the top of the screw head with my Dremel tool, then use a large standard screwdriver to break it loose.

Anyway, I found the valve to be dirty and difficult to turn. After cleaning with carb cleaner it turned very easily. Reassembly was very easy and upon startup, the problem was gone. Excellent post! Much thanks to GSSS. My only advice is to have a backup plan if you strip some screw heads.

[Diabolus1]

I also want to comment and thank the OP for posting this. Spent two hours today taking everything apart and cleaning it, car runs great now.

One question, does anyone how to order the three replacement screwes for the right valve body? The screws and damn near impossible to get out, and I stripped one of them. I was able to use a lock jaw to tighten it in, but I want to replace it.

[MauiCVR]

Thank you so much. Saved $700! Completely worth the hour of time!!!

[Nabby]

Is the IAC valve actually necessary? I've heard from people with various other cars, that some modders like to just remove their IAC and turn up the idle screw on the TB to compensate, and the only time it has a problem without it is with like the A/C on.

[madmark]

Hello Everyone,

I know IACV has been a huge topic on the forum and I have found various pictures in the RX forum and ES forum on the idle air control valve (IACV) or as others call it the idle speed control valve (ISC). However, I have not found a "step by step" posting to date which definitively shows how to clean this thing so that my car stops giving me idling problems.

Symptoms I have had included:

- low and rough idling that would cause the car engine to start shaking after starting the car

- this eventually got worse to the point that when I start my car, it would not idle unless I gave it gas

- idling problems for me tended to occur more often after my engine was warm or had been sitting in the sun

I hope these series of postings help you fellow LOC members out there. You've certainly helped me in the past so here's my two cents at this common problem. Additionally, the instructions I give are the way in which I have cleaned it myself. As you go about and attempt this, you may find better ways to do so. Please add and refine my instructions/terminology as needed. I am not a professional. I've only changed my oil, air filters, and conducted minor maintenance previously. The bottom line is that if you have the right tools, you should be able to do this. This discovery/ cleaning took me about 2 hours to do cause I ran into problems and there were major steps left out in previous postings that Ive encountered read. The next time I do this, I believe I can get this done in about an hour or less.

Tools Needed:

1) Tightly fitting Philips Screw Driver

2) Carb cleaner that is O2 sensor safe (I've seen CRC. I used Valvoline Carb Cleaner)

3) Locking Grip Pliers (definitely helped me remove the factory tight screws)

4) Small brush for cleaning

5) Towels for cleaning

6) Pliers (help removed brackets holding the hoses)

7) Latex gloves helps with limit the messiness.

* I used the same gasket and did not replace it. No problems found.

1) Remove the hose that comes from the engine/motor that connects to the air intake hoses.( Hose is below in red well refer to this as Hose A) When you pull back the rubber hose covering, you will see that a metal bracket is holding the hose pretty tightly in place. Use the pliers to clasps the two metal pieces together to loosen the bracket and pull the hose loose. You can also do this by hand if its easier for you.

original_2.JPG

2) Upon removing the hose, you will want to remove the two air intake hoses. Loosen the three screws above in green and remove the hose. Below is a picture of the intake hoses removed.

intake_hoses_only.JPG

3)After removing the intake hoses, I opened the lid to the air filter and moved this to the side of the car to create more working room. I believe there are two clips on the right holding the lid in place. Just pop the two clips and move the cover to the side. I also took out the air filter and temporarily moved this to the side.

intake_h..._removed.JPG

4)After removing the intake hose, the throttle body/IACV/black electric coil is revealed. At this point, I removed the black electric wire from the black coil. Once the electric wire is removed you can remove the black coil from the IACV by removing the two screws. Note, the screws are factory tight so use a tight fitting screw driver to remove the screws. One of my screws was partially stripped from the dealerships work, so I had to resort to my locking grip pliers which helped out tremendously. After removing the two screws, the black electric piece pops right off. When the black electrical coil is removed from the IACV, it exposes a small pencil sized metal stud. You will also notice a washer that sits on this stud. Dont lose this washer. Take it and put it aside so it doesnt fall off when you continue on in the next steps.

throttle...evealed2.JPG

5)Additionally, I removed the hose coming out of the IACV. Well call this Hose B. This hose can be removed in the same manner by clamping the bracket and pulling the hose out. You will see that the hose is removed below. Below are pictures of before and after.

sensor_removed2.JPG

6)Here is where the fun begins. I initially attempted to remove the four screws attached to the IACV at this point, but found that after an hour, this would be nearly impossible to remove considering the location of the screws were in an extremely tight spot. The only way I would be able to remove the IACV is to remove right throttle body. Not as tough as it sounds. Three screws need to be removed to accomplish this. Again, be careful when removing the screws. Also you will see I removed another electric plug and I also cut a tie wrap. Once you complete these steps, the throttle body/ IACV comes out pretty easily. Note when you remove the throttle body, there will be one LAST hose connected to the IACV. Be careful when you remove this hose as radiator fluid may spill. Some of my fluid spilled out so I just refilled my coolant after I was done.

throttle...nnected2.JPG

7)Below is a picture of the bottom view of the IACV. You now can EASILY remove the four screws connecting the IACV to the throttle body . In the picture below, I have already removed one of the screws.

bottom_view_iacv.JPG

Once the four screws are removed the IACV and throttle body separate. Now you can clean both of them with your carb cleaner, brush, towels, cotton swabs etc. Picture here is before I the cleaning with all the muck inside

iacv_removed.JPG

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

post_thr...cleaning.JPG

iacv_upclose.JPG

iacv_post_cleaning.JPG

8) Once you are done cleaning, just put back the throttle body/iacv the same way you took it off, and put everything back in reverse order. Ensure the gasket is in place. Also, ensure you put the washer back on the electric coil. Make sure you place hose A & B back and ensure the electric plugs are back in their original position. Once these things are in place, then it's all about putting the air filter/hoses back and you are good to go. If you have lost any coolant, make sure you refill it to a safe level.

After completing this cleaning, my car starts up without any problem and idles as if I just purchased the car brand new. Replacing this at a dealership would have costed me $300-400 easily. Let me know if you have any questions. Cheers (Also, I tried to post these as separate replys, but the software combined all my replies into a single reply and did not keep them separated)

*Edited the posting to have the pictures follow step by step in sequential order*

This Post was AMAZING & a money saver... I ran into one small probelm, after i removed the throttle body and cleaned it. I must have lost the rubber O ring that conects the coolent hose to the throttle body... Could you post a picture of the ring needed? Will any small rubber ring work?

[GoldenStateSilverSport]

Hey Gang - It's been awhile since I've visited this thread. Glad to see that this has helped soo many people!! For those who plan on going through with this DIY fix, I'd like to re-iterate the screws are tough to take out so be prepared with the proper tools to remove them. Also glad to see one of the posters mentioned it possible to stop by a home depot and pick up some extra replacement screws for a few dollars!

"As stated by ml30306 in post# 170, if you want to replace the 3 screws
for the throttle unit for the RX300, get 2 units with bolt size M6 with
1" pitch and length of 60mm and another one with size M6 and length of
28 mm also with 1" pitch. Diameter of the screws is ~5mm."

[Kerri]

We did all of this about 1 1/2 years ago and car ran fine until now, but is now having low idle and starting issues again. O2 sensor codes are coming up. Should this cleaning last more than 2 years, and if not, should this part be replaced at this point?

[robz]

Thank you very much for the detailed instructions, decriptions (VERY tight Phillips #3 screws on throttle body, etc.), AND very clear pictures. I would have thrown in the towel if I was doing this without your expert help. I have been dealing with the intermittant no-idle for at least a year. Looking forward to not braking with my left foot while keeping the accelerator pressed to keep the car running.

Rob Z

2000 RX300, 162,000 miles

[CsKid9]

Im gonna be trying this tommorow. Im on a low budget so i hope this helps, the only money i have spent so far is for the throttle body gasket. My dad and I saw a bunch of videos saying just to spray carbirator cleaner in the hole in which the air comes out. it started running a hole lot better but i am going to be as anal as i want when it comes to the well being of my car. Im going to be cleaning the throttle body and IACV.

[bark5252]

By the way, I've been driving my car for 2+ days now after performing this cleaning and I can happily say I have not received any idling problems anymore. The car starts and idles perfectly now. Cheers!

By the way, I've been driving my car for 2+ days now after performing this cleaning and I can happily say I have not received any idling problems anymore. The car starts and idles perfectly now. Cheers!

Hello Everyone,

I know IACV has been a huge topic on the forum and I have found various pictures in the RX forum and ES forum on the idle air control valve (IACV) or as others call it the idle speed control valve (ISC). However, I have not found a "step by step" posting to date which definitively shows how to clean this thing so that my car stops giving me idling problems.

Symptoms I have had included:

- low and rough idling that would cause the car engine to start shaking after starting the car

- this eventually got worse to the point that when I start my car, it would not idle unless I gave it gas

- idling problems for me tended to occur more often after my engine was warm or had been sitting in the sun

I hope these series of postings help you fellow LOC members out there. You've certainly helped me in the past so here's my two cents at this common problem. Additionally, the instructions I give are the way in which I have cleaned it myself. As you go about and attempt this, you may find better ways to do so. Please add and refine my instructions/terminology as needed. I am not a professional. I've only changed my oil, air filters, and conducted minor maintenance previously. The bottom line is that if you have the right tools, you should be able to do this. This discovery/ cleaning took me about 2 hours to do cause I ran into problems and there were major steps left out in previous postings that I’ve encountered read. The next time I do this, I believe I can get this done in about an hour or less.

Tools Needed:

1) Tightly fitting Philips Screw Driver

2) Carb cleaner that is O2 sensor safe (I've seen CRC. I used Valvoline Carb Cleaner)

3) Locking Grip Pliers (definitely helped me remove the factory tight screws)

4) Small brush for cleaning

5) Towels for cleaning

6) Pliers (help removed brackets holding the hoses)

7) Latex gloves helps with limit the messiness.

* I used the same gasket and did not replace it. No problems found.

1) Remove the hose that comes from the engine/motor that connects to the air intake hoses.( Hose is below in red – we’ll refer to this as Hose A) When you pull back the rubber hose covering, you will see that a metal bracket is holding the hose pretty tightly in place. Use the pliers to clasps the two metal pieces together to loosen the bracket and pull the hose loose. You can also do this by hand if it’s easier for you.

original_2.JPG

2) Upon removing the hose, you will want to remove the two air intake hoses. Loosen the three screws above in green and remove the hose. Below is a picture of the intake hoses removed.

intake_hoses_only.JPG

3)After removing the intake hoses, I opened the lid to the air filter and moved this to the side of the car to create more working room. I believe there are two clips on the right holding the lid in place. Just pop the two clips and move the cover to the side. I also took out the air filter and temporarily moved this to the side.

intake_h..._removed.JPG

4)After removing the intake hose, the throttle body/IACV/black electric coil is revealed. At this point, I removed the black electric wire from the black coil. Once the electric wire is removed you can remove the black coil from the IACV by removing the two screws. Note, the screws are factory tight so use a tight fitting screw driver to remove the screws. One of my screws was partially stripped from the dealership’s work, so I had to resort to my locking grip pliers which helped out tremendously. After removing the two screws, the black electric piece pops right off. When the black electrical coil is removed from the IACV, it exposes a small pencil sized metal stud. You will also notice a washer that sits on this stud. Don’t lose this washer. Take it and put it aside so it doesn’t fall off when you continue on in the next steps.

throttle...evealed2.JPG

5)Additionally, I removed the hose coming out of the IACV. We’ll call this Hose B. This hose can be removed in the same manner by clamping the bracket and pulling the hose out. You will see that the hose is removed below. Below are pictures of before and after.

sensor_removed2.JPG

6)Here is where the fun begins. I initially attempted to remove the four screws attached to the IACV at this point, but found that after an hour, this would be nearly impossible to remove considering the location of the screws were in an extremely tight spot. The only way I would be able to remove the IACV is to remove right throttle body. Not as tough as it sounds. Three screws need to be removed to accomplish this. Again, be careful when removing the screws. Also you will see I removed another electric plug and I also cut a tie wrap. Once you complete these steps, the throttle body/ IACV comes out pretty easily. Note when you remove the throttle body, there will be one LAST hose connected to the IACV. Be careful when you remove this hose as radiator fluid may spill. Some of my fluid spilled out so I just refilled my coolant after I was done.

throttle...nnected2.JPG

7)Below is a picture of the bottom view of the IACV. You now can EASILY remove the four screws connecting the IACV to the throttle body . In the picture below, I have already removed one of the screws.

bottom_view_iacv.JPG

Once the four screws are removed the IACV and throttle body separate. Now you can clean both of them with your carb cleaner, brush, towels, cotton swabs etc…. Picture here is before I the cleaning with all the muck inside

iacv_removed.JPG

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

post_thr...cleaning.JPG

iacv_upclose.JPG

iacv_post_cleaning.JPG

8) Once you are done cleaning, just put back the throttle body/iacv the same way you took it off, and put everything back in reverse order. Ensure the gasket is in place. Also, ensure you put the washer back on the electric coil. Make sure you place hose A & B back and ensure the electric plugs are back in their original position. Once these things are in place, then it's all about putting the air filter/hoses back and you are good to go. If you have lost any coolant, make sure you refill it to a safe level.

After completing this cleaning, my car starts up without any problem and idles as if I just purchased the car brand new. Replacing this at a dealership would have costed me $300-400 easily. Let me know if you have any questions. Cheers (Also, I tried to post these as separate replys, but the software combined all my replies into a single reply and did not keep them separated)

*Edited the posting to have the pictures follow step by step in sequential order*

[hsmac]

hey guys, attempted to do the repair after all your successes. took me 1.5 hours and i finally got the two front screws off, exposing the throttle body. after seeing 3 more screws, i wasn't surprised that they wouldn't budge despite a snug fit and a lot of exertion. called it a day after being exhausted and discouraged. i know i can get two of those 3 screws off eventually, but it's that last screw that i'm worried about. can't even see it and there's no way to use pliers there. i already stripped those first two screws (and a lot of the part body while using pliers to remove them) and am just planning to replace all the screws with new ones. i'm wondering how much easier it will be if i were to buy an impact driver, but i'm also scared to strip that hidden screw since there would be no way to remove it if stripped. considering my mechanic would've charged $120 or so to fix this, i think i've probably already lost.

**update** got an impact driver, still no luck after lots of banging. I wouldn't recommend this job as a DIY.

**2nd update** tried bolt extractors as suggested, no luck. stripped screws inside and out. several hours and cannot even get to the iacv. i strongly do not recommend this DIY.

[dchan865]

Last time I cleaned my IACV was about 26 months ago at 201,000 miles. Now at ~225,000 miles, the car started to have low idle and several thousand miles ago, the car stumbled/hesitated initially during standing start. Well, I just cleaned the IACV again and the idle is back to normal again, and acceleration is much more smoother now. Since its my 3rd time doing it, it only took me about 1 hour. BTW, someone posted a You Tube video of how to do this and offered some advice/logic why its important that you disconnect the bottom hose so all the cleaner does not go down to the crankcase(i think that's what its called?). I followed that advice and spent a little more effort in cleaning than last time, so hopefully this cleaning will last longer. We shall see. Cheers everyone!

[Ximian]

For the life of me, I can't get the screws out of the Throttle body to remove the right side. I'm going to have to take off the whole assembly. Any secrets to removing those screws (i.e. for the right side throttle body only)?

[ml30306]

I did this for my 2000 Lexus ES300. I now have a 2004 Lexus ES330 - is it the same here as well?

[dfarnan]

This thread has been out here for a long time but I used the instructions yesterday for an 2003 RX300. Your instructions and pictures were a great help. I will add some notes from my experience;

I used a #3 Phillips pozi screwdriver bit on the 3 screws holding the throttle body. They were definitely torqued but the pozi bit fit very tight and worked great. I did need 'help' with one of the screws holding the IACV to the throttle body. They were also very tight. 3 worked fine but the 4th one seemed ready to strip so I used the 52168 extractor set from Sears. The 52168 set worked great. The picture shows using them with a drill but I used a hand driver which did very little damage and so was able to reuse the screw.

My wavy washer on the electrical coil shaft didn't pop out of the recess at the back of the magnetic shaft when I removed the coil so I wasn't sure where it was. I put a small plastic tray under it just in case it fell as I continued.  As I loosened the throttle body it came out of the recess so I took it off and put it to the side. You definitely don't want to lose it.

 You don't have to cut the tie-wraps on the side and top of the throttle body.  I used a small flat bladed screwdriver to reach behind the two holders to press in the tabs that hold them in the bracket. Press one in and tilt the plastic piece enough so it doesn't pop back out then press the other side in and it came right out. When putting it back just pressed it in.

Regarding the tube that comes from below and connects to the metal tube that goes straight up into the IACV (not the one that is L shaped) you mentioned 'some leakage' of anti-freeze....I wasn't paying enough attention to that and dumped most of the coolant reservoir on my garage floor before I heard it going on the floor and got something under it. Then I figured out if I had just lifted the hose up higher (than the reservoir) it might not have leaked but I stopped it up with a yellow wire nut I had on the work bench. It plugged it up nicely. No more leaking. 

 I used CRC carb cleaner and it didn't seem to clean as well as yours...also it seems you need several different sizes of small brushes to clean it out well. Maybe tiny bottle brushes or something. It being Sunday and I was headed out of town I did the best I could with what I had but did not get it as clean as yours. As another person posted his IACV also had the problem where it was sticking when it was turned in one direction Mine was doing that also but in addition it had a couple of sticky spots as I turned it. Felt like it had rough bearings. As soon as I got that shaft completely clean (both sides) it turned smoothly. After I reassembled last night I drove the car for an hour or so (before leaving town) with no rough idles and it seemed to start quicker than it had been but not too sure about that one. 

Just one more note on the various screws. Sent my wife to the dealer to get the 3 Throttle body screws and 4 of the IACV to Throttle body screws before starting. They gave her 3 of the top throttle body screw (which is much shorter than the other 2 screws) and told her the IACV to throttle body could not be replaced because they are 'glued' in. If you've read down to this point you know they can. ACE Hardware has screws the same diameter and thread count (sorry I don't remember the exact size ...M5-8 I think) but at my local ACE the screws were either slightly shorter or slightly longer than the one I used the screw extractor on. I took the longer ones and some washers but since I didn't damage the original very much with the screw extractor I reused it and it tightened up just fine. 

Again thanks for the very helpful instructions....and hope my experience helps someone else.

[Tabrice]

Thank you for the detailed instructions.  My 2000 rx300 has had some rough starts within the last month and I decided to clean the iacv before it got worse.  Did it today with no problems other than stripping two screws.  Managed to get them off with vise grips however I think I should replace the screws someday.   Hopefully for a long time,  I don't experience the sudden shut off when I start my car.   My rx300 has 310,000 miles with little maintenance on my part.  Runs great and I hope it will stay this way for at least another year.  Thanks again!

[2harmonizeme]

I had someone attempt to clean the idle control valve on my 99 rx300. I'm not sure what he did but now it's revving up and down when in park and idles at 30mph when in drive and the rpms are over 3 when driving. What's wrong with it. 

Help please!!!!

[2harmonizeme]

I had someone attempt to clean the idle control valve on my 99 rx300. I'm not sure what he did but now it's revving up and down when in park and idles at 30mph when in drive and the rpms are over 3 when driving. What's wrong with it. 

Help please!!!!

[garne2t]

Old thread still providing new value to people like me. Thanks! Fixed my 2003 RX300 with 170,000 miles this weekend. Happy it lasted this long without IACV needing cleaning.

Some observations:

1) This was not that easy for me and took about 5 hours including time to read blog and trips to autoparts store.  I thought I was mechanically inclined but maybe because my car is old each step was that much more difficult.

2) Definitely recommend getting needle nose clamping pliers AND and a small hand impact screwdriver. All of my screws were very difficult to remove! I didn't have enough room for the impact driver in the early screw removal steps and the pliers tip is too big for the later steps.

3) Getting hoses off was very difficult on my old car. For the smaller ones, use pliers with enough force to twist hose loose but not so much force as to rip hose. For large air hose in first step, pry back the hose a little with a flat head screwdriver to loosen.

4) I read the whole blog and warning about the wavy, brass colored washer. I never saw it during disassembly. After re-assembly and moving car, there it was in a puddle of coolant. :(  The car has been running perfect for two days so I guess it is not needed. Why in the heck is it there if it is not needed as others have reported?  :) Think there will be any longer term negative impact of the washer missing?

Thanks again for the post!

[dchan865]

Hmm, you sure it was coolant and not carb cleaner? Anyway, for me that 2 screw were the hardest ones to take out for the first time. The entire process probably closed to the amount of time you put in.  After that it got easier. The screw material is software so it not careful, it could get damaged easily if too much force or the wrong tool is used. Not really sure what the purpose of that ring is, it doesn't look like a gasket to me. I guess if your car idles properly and car runs smooth, probably not a concern.