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

[Oiler62]

Thanks Golden State--you are the man!! I just finished taking the iacv/throttle body apart and cleaned it up real good. Runs great, no leaks and I feel great saving big money.

I did strip some screws and had to get a small vise-grip pliers at Sears to get them off. $12 well spent to save a couple hundred.

I'll try to return the favor and help people with their problems, offer suggestions on things, etc.. I'm in no way a mechanic but will tackle stuff like this to save that $75/hr labor.

Thnaks again!!

[mmbyrum]

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.

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.

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.

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.

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.

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.

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.

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

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

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*

[GoldenStateSilverSport]

Thanks Golden State--you are the man!! I just finished taking the iacv/throttle body apart and cleaned it up real good. Runs great, no leaks and I feel great saving big money.

I did strip some screws and had to get a small vise-grip pliers at Sears to get them off. $12 well spent to save a couple hundred.

I'll try to return the favor and help people with their problems, offer suggestions on things, etc.. I'm in no way a mechanic but will tackle stuff like this to save that $75/hr labor.

Thnaks again!!

$75/hr is definitely not cheap and that's probably one of the "cheaper" rates around here. This process wasn't so bad to do so glad I could help. Happy Holidays!

[late2party]

I know this thread was started more than two years ago, but since there are still tons of RX300/ES300 out there, this information is still very relevant and useful. I just want to say a big thank-you to GSSS and Geoff1 for posting such detailed and useful information. They took their time to explain what they did to help their fellow Lexus enthusiast/DIYer's. Hopefully everyone will be so willing to share as they do.

So here is my experience. I have a 99 ES300 with about 103K miles. About 1 month ago, I started having difficulty starting the car when it was cold. The car would start, ran at about 250rpm, then died. After that initial start, the car would not start unless I tapped the gas pedal while starting. Once the car started, I had to bring it up to fast idle, then it would idle by itself fine. No trouble starting when the engine was warm. No trouble with idling while the engine was running. After doing some searches, I came upon this forum, and I have to say this is probably the most detailed and accurate information out there. I initially thought about taking the whole throttle body off, then I decided to just use the short cut. After I took the coil pack off, I could definitely feel some resistance while turning the pintle shaft. I sprayed some cleaner into the small hole in the throttle body and around the pintle shaft. Just a couple of sprays and the shaft felt like it was gliding on a ball bearing (actually it is.) I sprayed a couple more time just be sure. Re-assemble everything, and the car started right up. I am going to observe for a couple of month before I can declare this short cut a success. I suppose if this problem returns too quickly, then I am going to have to do a more thorough cleaning. Several observations:

1) I bought a manual impact driver from Sears as suggested, just in case. It turned out that I didn't need it. What I did was I put a phillip bit inside of a 1/4 socket, which is attached to a rachet handle. The trick is to place firm pressure over the screw heads while turning the handle. Care must be taken so the phillip bit does not fall out of the socket. The screws came off fairly easily.

2) I initially did not see the wavy washer on the pintle shaft since the washer is so small. Then I saw it and went to grab it, and that's when it jumped out of my hand. That's the last I saw of it, as I spent the next 30 minutes looking for it in the engine compartment and on the floor to no avail. So I just put everything back together without it. I don't know exactly what's going to happen long term. I also wonder if I'll be able to just buy this wavy washer if it is a critical part.

3) I put a small cup under the lower air inlet to collect the throttle body cleaner as it traveled through the inner passages. Maybe it wasn't necessary, but I am just kind of weird about it.

I will give an update after a couple of months of driving.

Now only if that tapping noise from the suspension over broken pavement will go away......

[thomaskuhn]

I just want to thank everyone for this great fix!! It worked great on my wife's RX300. The only issue we had after the fix was a high idle and then the check engine light came on. But we will cross that bridge later.

[code58]

2) I initially did not see the wavy washer on the pintle shaft since the washer is so small. Then I saw it and went to grab it, and that's when it jumped out of my hand. That's the last I saw of it, as I spent the next 30 minutes looking for it in the engine compartment and on the floor to no avail. So I just put everything back together without it. I don't know exactly what's going to happen long term. I also wonder if I'll be able to just buy this wavy washer if it is a critical part.

Just a little tip- I was fortunate enough not to drop the wave washer- but if you do..... I have more tools than it should be legal for 1 man to have (I spent my life in automotive work of one form or another) but if I drop (and lose) a small part like that I take the long wanded air blower and blow (not real hard) all around in the area that you dropped it in under the hood. Most of the time that will dislodge it and you will find it under the car. I also use a very powerful magnet on an adjustable handle (Harbor Freight) and scan the area with it to pick up the part if it is small enough that I don't readily see it. Hopes this helps those of you that have air and a powerful magnet. LOL

[code58]

1) I bought a manual impact driver from Sears as suggested, just in case. It turned out that I didn't need it. What I did was I put a phillip bit inside of a 1/4 socket, which is attached to a rachet handle. The trick is to place firm pressure over the screw heads while turning the handle. Care must be taken so the phillip bit does not fall out of the socket. The screws came off fairly easily.

I assume you mean the type you hit with a hammer and it helps (spiral) the screw in whichever direction it is set to. I have 2 different sizes of those and they are great when you really need them. I used a 3/8 impact set low (so as not to strip the SOFT Japanese screws) and it worked just fine. The nature of the soft Japanese metal in the bolts and screws is that it "seizes" against the adjacent metal. It's not that it is tightened excessively at the factory, that's why when it does let go it is immediately loose. A harder bolt isn't able to "get it's fingers" into the adjacent metal so doesn't "seize" the way the soft does.

[late2party]

Even though it has only been a little more than a week since I cleaned the IAC, but I could tell a definite improvement. As for the wave spring washer that I dropped but couldn't find, it didn't seem to make any difference, as far as I could tell. Funny thing is, in addition to solving the cold start problem, the car also shifts a lot better. The car used to "lurch" when shifting from 1st to 2nd, and now the shift is so smooth that I don't even notice it unless I look at the tach. I am wondering if anyone else has a similar experience?

[code58]

Even though it has only been a little more than a week since I cleaned the IAC, but I could tell a definite improvement. As for the wave spring washer that I dropped but couldn't find, it didn't seem to make any difference, as far as I could tell. Funny thing is, in addition to solving the cold start problem, the car also shifts a lot better. The car used to "lurch" when shifting from 1st to 2nd, and now the shift is so smooth that I don't even notice it unless I look at the tach. I am wondering if anyone else has a similar experience?

I took a look at the old IACV out of my DIL's RX and I couldn't see any reason for the wave washer. It LOOKED like insurance that it didn't need. It would hold the bearing in place but I tugged on the end of the shaft that rides in that bearing and it didn't seem like it was going anywhere. If you still had it apart I would send you this wave washer but I don't think you'll need it.

[vheuser]

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.

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.

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.

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.

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.

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.

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.

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

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

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 description was awesome. The vehicle now works better than the last 50k miles. It now has 167k on it.

Thanks again

[ziggy211]

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.

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.

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.

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.

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.

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.

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.

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

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

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 description was awesome. The vehicle now works better than the last 50k miles. It now has 167k on it.

Thanks again

[lenore]

I know this thread was started more than two years ago, but since there are still tons of RX300/ES300 out there, this information is still very relevant and useful. I just want to say a big thank-you to GSSS and Geoff1 for posting such detailed and useful information. They took their time to explain what they did to help their fellow Lexus enthusiast/DIYer's. Hopefully everyone will be so willing to share as they do.

So here is my experience. I have a 99 ES300 with about 103K miles. About 1 month ago, I started having difficulty starting the car when it was cold. The car would start, ran at about 250rpm, then died. After that initial start, the car would not start unless I tapped the gas pedal while starting. Once the car started, I had to bring it up to fast idle, then it would idle by itself fine. No trouble starting when the engine was warm. No trouble with idling while the engine was running. After doing some searches, I came upon this forum, and I have to say this is probably the most detailed and accurate information out there. I initially thought about taking the whole throttle body off, then I decided to just use the short cut. After I took the coil pack off, I could definitely feel some resistance while turning the pintle shaft. I sprayed some cleaner into the small hole in the throttle body and around the pintle shaft. Just a couple of sprays and the shaft felt like it was gliding on a ball bearing (actually it is.) I sprayed a couple more time just be sure. Re-assemble everything, and the car started right up. I am going to observe for a couple of month before I can declare this short cut a success. I suppose if this problem returns too quickly, then I am going to have to do a more thorough cleaning. Several observations:

1) I bought a manual impact driver from Sears as suggested, just in case. It turned out that I didn't need it. What I did was I put a phillip bit inside of a 1/4 socket, which is attached to a rachet handle. The trick is to place firm pressure over the screw heads while turning the handle. Care must be taken so the phillip bit does not fall out of the socket. The screws came off fairly easily.

2) I initially did not see the wavy washer on the pintle shaft since the washer is so small. Then I saw it and went to grab it, and that's when it jumped out of my hand. That's the last I saw of it, as I spent the next 30 minutes looking for it in the engine compartment and on the floor to no avail. So I just put everything back together without it. I don't know exactly what's going to happen long term. I also wonder if I'll be able to just buy this wavy washer if it is a critical part.

3) I put a small cup under the lower air inlet to collect the throttle body cleaner as it traveled through the inner passages. Maybe it wasn't necessary, but I am just kind of weird about it.

I will give an update after a couple of months of driving.

Now only if that tapping noise from the suspension over broken pavement will go away......

the tapping noise is probably the front shock strut upper mounts, they need to be replaced. lots of info on those in the forums too...

[The Boi Next Door]

Well i have a lexus sc400, and it has done that in the past but it seems like when im sitting at a red light or something to that effect and its hot, it will just suddenly die. Will this fix my problem??

Thanks

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.

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.

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.

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.

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.

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.

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.

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

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

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*

[capnfred]

Great Post, I have just gotten a well used 93 es300 with 180k on the clock. I am suffering from intermittent idling problems, so I am guessing I have an IACV cleaning in my immediate future, the previous owners had many things on the car misadjusted to compensate for other problems, I am slowly but surely finding them and getting them right, (the way the engineers designed it). I will use your post as a guide and when finished If I find any areas to critique I will. I have been wrenching for 50 plus years.... started out pretty young....anyway I am looking forward to getting it right, it appears to be a great car.... the previous owner was a very young man and he was fortunate that the car did not kill him.... so many problems with suspension and steering. Anyway thanks again.. sounds like the cats meow! (grin)

Capn

[geheren]

I have performed this procedure twice. Only because I had a check engine light. No symptoms. The first time it lasted three months the second time one day. Is there another sensor on the idle control code? this time when I let off the gas I get small surges.

[code58]

I have performed this procedure twice. Only because I had a check engine light. No symptoms. The first time it lasted three months the second time one day. Is there another sensor on the idle control code? this time when I let off the gas I get small surges.

Geheren_ When you say you performed this twice, did you take it off and clean it thoroughly? Some have simply shot carb. cleaner or something that would dissolve some or all of the dirt that impedes the movement of the round cylinder. That is the easy way and I have no argument with anyone in how they choose to do the work on their own car, but I don't like doing things over down the road so I choose to do the very best I can the 1st. time around. If you took it off, how dirty was it? Something is definitely wrong if you took it off and cleaned it and it lasted 1 day. The cylinder should move freely and there is a procedure in the factory manual that you should be able to use to test it before you ever reinstall it or put the coolant back in. Maybe it needs to be replaced, but as with anything, I like to make SURE it needs the part before I put it on, especially at the price of Toyota/Lexus parts. Let us know some more of the details.

No other sensor that I know of.

[capnfred]

Well I now know the IACV on ES-300 is totally different than on your cars, Mine appears to be much simpler, and therefore easier to maintain, anyway I took it all apart, cleaned it till it shined, then re-assemled evrything. Did not see any big changes, so then I tackled the TPS, it too was a bit dirty ut everything moved, but I cleaned it too. Still no big difference in idling. I was doing it step by step to determine which component has the greatest effect, finally I pulled the EGR Valve assy. VOILA, finally something concrete, when I removed the dashpot, lots of powdered carbon fell out, maybe as much as a Tsp. After re-assembly, I had to re-adjust the idle speed, now when it idles it is nice and smooth, the speed is the same whether it is in gear, nuetral, AC on or off........so by the process of elimination the EGR Valve was the culprit. Time will tell I guess, this is on a vintage ES with 180k on the clock. If there are any ES-300 owners that would like to see a step by step, I will post one, its pretty easy, nothing really tricky about it....the only part that was the least bit difficult was the hose removal. on the ES the IACV is wide open, easy to get to, and easy to clean.

Capn

[code58]

Well I now know the IACV on ES-300 is totally different than on your cars, Mine appears to be much simpler, and therefore easier to maintain, anyway I took it all apart, cleaned it till it shined, then re-assemled evrything. Did not see any big changes, so then I tackled the TPS, it too was a bit dirty ut everything moved, but I cleaned it too. Still no big difference in idling. I was doing it step by step to determine which component has the greatest effect, finally I pulled the EGR Valve assy. VOILA, finally something concrete, when I removed the dashpot, lots of powdered carbon fell out, maybe as much as a Tsp. After re-assembly, I had to re-adjust the idle speed, now when it idles it is nice and smooth, the speed is the same whether it is in gear, nuetral, AC on or off........so by the process of elimination the EGR Valve was the culprit. Time will tell I guess, this is on a vintage ES with 180k on the clock. If there are any ES-300 owners that would like to see a step by step, I will post one, its pretty easy, nothing really tricky about it....the only part that was the least bit difficult was the hose removal. on the ES the IACV is wide open, easy to get to, and easy to clean.

Capn

Capn- Thanks for sharing that with us. The more knowledge we have, the more power over our own mechanical problems we have. Even though you car may be a different model and vintage than those here it still gives us more "tools in our tool bag"

[geheren]

I have performed this procedure twice. Only because I had a check engine light. No symptoms. The first time it lasted three months the second time one day. Is there another sensor on the idle control code? this time when I let off the gas I get small surges.

Geheren_ When you say you performed this twice, did you take it off and clean it thoroughly? Some have simply shot carb. cleaner or something that would dissolve some or all of the dirt that impedes the movement of the round cylinder. That is the easy way and I have no argument with anyone in how they choose to do the work on their own car, but I don't like doing things over down the road so I choose to do the very best I can the 1st. time around. If you took it off, how dirty was it? Something is definitely wrong if you took it off and cleaned it and it lasted 1 day. The cylinder should move freely and there is a procedure in the factory manual that you should be able to use to test it before you ever reinstall it or put the coolant back in. Maybe it needs to be replaced, but as with anything, I like to make SURE it needs the part before I put it on, especially at the price of Toyota/Lexus parts. Let us know some more of the details.

No other sensor that I know of.

I greatly appreciate your feedback, as it turns out I left 2 sensors unplugged, lucky the car even ran. Engine light went right out, car runs fine. Thanks

[phobang]

similar to RX300, i have the es300

i just cleaned myIACV on my 01 ES300, and after driving for a few minutes the temperature starts to increase. thinking its a clamp (though i double checked all clamps are on properly), maybe clamp broke? or should i replace both the intake gasket and the rubber IACV gasket? any other way it could be leaking coolant? some sweet smelling smoke now coming from under the hood (coolant?)

also my idle is now 1000-1500 is there a way to fix that? reposition the magnet plug (read that somewhere) or will it correct itself?

anyone else have these problems?

[rg1]

Well I now know the IACV on ES-300 is totally different than on your cars, Mine appears to be much simpler, and therefore easier to maintain, anyway I took it all apart, cleaned it till it shined, then re-assemled evrything. Did not see any big changes, so then I tackled the TPS, it too was a bit dirty ut everything moved, but I cleaned it too. Still no big difference in idling. I was doing it step by step to determine which component has the greatest effect, finally I pulled the EGR Valve assy. VOILA, finally something concrete, when I removed the dashpot, lots of powdered carbon fell out, maybe as much as a Tsp. After re-assembly, I had to re-adjust the idle speed, now when it idles it is nice and smooth, the speed is the same whether it is in gear, nuetral, AC on or off........so by the process of elimination the EGR Valve was the culprit. Time will tell I guess, this is on a vintage ES with 180k on the clock. If there are any ES-300 owners that would like to see a step by step, I will post one, its pretty easy, nothing really tricky about it....the only part that was the least bit difficult was the hose removal. on the ES the IACV is wide open, easy to get to, and easy to clean.

Capn

When you say vintage, what year is it? I plan on doing this procedure on my 2000 es 300 and Im wondering if I will have to mess with the TPS and EGR.

Thanks.

-Rob

[phobang]

i think i found the problem, gota replace the gaskets.. question, i have the iacv gasket that goes to the throttle body, but is there another round gasket that goes between the coolant recess holes from the throttle body? its not mentioned in this guide and i dont remember seeing one, anyone know?

reference this guide

http://www.clublexus.com/forums/rx-first-g...-fast-iacv.html

[phobang]

yup there is.. for those new to this, theres a total of 3 gaskets on my 2001 es300,

a paper-think gasket between the throttle body and air intake valve

a small round o-ring gasket between the coolant recess hole on the throttle body and air intake valve

the gasket between the iacv and the throttle body

these were not on stock at the dealer, so had to order takes 2 days

while ur ordering, you can also order new screws, 2 for the iacv, 4 for the iavc/throttle body, and 3 for the throttle body/air intake valve (1 short, 2 long)

[herbllewellyn]

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.

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.

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.

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.

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.

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.

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.

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

Pictures after I cleaned the IACV and throttle body

This last picture is the post throttle body cleaning

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*

[herbllewellyn]

Great instructions! Until last night I didn't know what a IACV was. I cleaned it this morning. When I opened it up, the valve was stuck. Cleaned it up and the car runs great.