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

[marinunited]

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*

[marinunited]

Thank you! After buying the recommended locking pliers (about $17) and coolant, my husband and son were able to follow your excellent instructions and clean the IACV as described. The car runs like a charm and my average mpg went up about 2.5%.

[roady94]

- Another happy customer!

I jumped here from a link on a Toyota Avalon Forum. I have a 2001 Avalon V-6, 132k mi., same engine as the ES300.

Symptoms: off-idle stumble, rough idle in gear, minor stumble on highway when moving to power enrichment, CEL. It was time for plugs and fuel filter anyway, so did all that - no change.

Did this IAC valve cleanout and the car runs like new again. Great write-up, excellent pics.

Thanks for taking the time.

[ES300ILL]

Wow, that was easy. Thanks for your time and the detailed information, great work!!

[cgaviator]

great instructions! I did this last night. The screws were way tight and I did strip 3 but finally got them out. Replaced them and got it all back together in 2 hrs.

[extreme915]

I just did mine today. It was stalling at red lights. My wife was worried about it, and i didnt want to spend countless dollars at the dealer. Thanks a milllion for this post. I have a subscription to alldata.com for my rx300 and they do not even mention the IACV or where it was loacted. Thanks again for this awesome post got mine done in about an hour. And yes my transmission seems to shift better too. Weird?

[fonzo91121]

Is this similar to the 1st gen gs 300

[cruzmike]

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*

Thank you for this great post, it saved me some ca$h.... :D :D

[MebaneRX300]

Just had to say that this post ROCKS! It saved me LOTS of $$$ and was the answer to my problem with my '00 RX300. The IACV was definitely "stuck" when I pulled it off the throttle body. A good cleaning with gas (didn't have carb cleaner available) did the trick. Runs great!

Thanks Golden State and everyone else. The internet is a wonderful thing for us DIYers!!!

Cheers from NC!!!

[ilovefood]

does this work for a 2000 ES300?

[code58]

does this work for a 2000 ES300?

Does the ES use the 1MFZE engine? If it does, it's probably similar, although in the back of my mind I'm thinking that the ES IACV LOOKS a little different. Though it MAY look a little different (or maybe not), the function should be the same, therefore the cleaning should be the same.

[jaz70115]

I found this to be an invaluable thread. Took me a little while to get the screws off and I really recommend the Craftsman “Bolt-Out”-Damaged Bolt/Nut Remover Set. I started this project without and couldn’t get the screws out. With the Craftsman “Bolt-Out”, the screws come right out. Getting the screws out is the biggest time variable. Everything else takes an hour. Removing the screws, however, can be an interminable task without the correct tools.

I found the attached body part document helpful.

My RX 300 is running like new…

thanks to all.

RX_300_throttle_body.pdf

[jayhawk32]

Just want to say thanks for your great post -- step by step instructions w/ photos was perfect...i was able to get the job done and the result is just as expected.

[kramer5150]

Great thread and thanks to the OP and all who have contributed. I just did the procedure this morning on my 2001 ES300, followed it step by step. Some of the air inlet ducts are different than the ones pictured but schematically its identical. its about a 90 minute job from start to finish.

Some I learned along the way...

-Good/new screwdriver or bits are a must. Those BIG blunt philips-head drivers you hardly use at the bottom of your toolbox are needed for this job. Other than that I had no troubles loosening the screws, there is enough room to grip and torque them adequately.

-Use caution around soft gaskets/parts. I used Electronics part solvent (spray can) thats safe for plastics and rubber. I find this a much less harsh chemical than carb / choke cleaner. I used q-tips to scrub the valve down. That 1/4" diameter magnet shaft should rotate freely for about a 1/8-1/4 turn. Mine was really gunked up with dirt and debris.

-I found it easier to just unscrew the metal mounting bracket that holds the wire zip-ties, removing / reusing those would have been more difficult.

-Keep a rag handy/wadded up under the work area in your engine to soak up coolant. I lost about a coke can amount. I worked on mine this morning with the engine cold.

-I have no idea what that wave washer does, I think it maybe there as an added safety to help retain the ball bearing.

Not bad, I just saved myself 5-700 bucks!!

Thanks again!!

[sjlexus]

I have a 2002 ES300 and tried using above description for cleaning my engine set up is really different can anyone please help me a diagram info or something???? after cleaning the throtle body and everthing I took off which looked fairly clean. In stead of engine dies at Idle it now does not die but will not rev up past 2k even when pushed to to floor HELP!!!!!!!!!!!!!!!!!!!!!!!

[kramer5150]

I have a 2002 ES300 and tried using above description for cleaning my engine set up is really different can anyone please help me a diagram info or something???? after cleaning the throtle body and everthing I took off which looked fairly clean. In stead of engine dies at Idle it now does not die but will not rev up past 2k even when pushed to to floor HELP!!!!!!!!!!!!!!!!!!!!!!!

Thats strange... Double check the throttle body cable/pully mechanism perhaps? is there anything obstructing its movement? I had to make sure the cable pulley was correctly seated against one of the adjustment screws when I was re-assembling mine. It almost sounds like its a physical limitation, rather than something electrical. I would think the OBDII would trigger the check engine light if it were something electronic. On that note, you might want to double check your cable harnesses, make sure they are fully inserted. FWIW... I used my electronics part spray cleaner and sprayed out all the gunk from my harnesses while I had them out.

I think the ES underwent a major overhaul + redesign from 01 to 02. Although schematically one would think they are similar.

I've been driving my ES-300 around for the past week and its been just fine through 1-tank of fuel. I think I have solved mine completely.

[code58]

I have a 2002 ES300 and tried using above description for cleaning my engine set up is really different can anyone please help me a diagram info or something???? after cleaning the throtle body and everthing I took off which looked fairly clean. In stead of engine dies at Idle it now does not die but will not rev up past 2k even when pushed to to floor HELP!!!!!!!!!!!!!!!!!!!!!!!

I agree with Kramer- I don't think there's any chance it's electrical or electronic. I'm betting if you go back over the other stuff you messed with and check all the throttle mechanism, you'll find the problem. No chance the IACV could do that. You have an '02- do you know if you have throttle by wire rather than cable? My wife's '02 Camry has "drive by wire", which I believe was the 1st year for it. See if you have a cable or not. If no cable, you may have messed up something in the servo (motor that opens the throttle). Otherwise, check the cable.

[jeharter]

Hey - A heartfelt thank you to all who contributed to this posting! I followed the instructions and the proceedure worked like a dream!

Many thanks

[deuterij]

Judging from the number of responses, IACV seems to be the number one reliability issue for these Lexus/Toyota V6s. Our ES300 had it too. Not wanting to tear up too many seal gaskets or screws, I tried the short-cut method of spraying the pintle area and idle air passage with carb cleaner then WD40 after removing the black solenoid cover. It did not give me a good feeling because the design causes drippings to collect at the bottom of the throttle body where the IACV is mounted. It worked for a few months but now the problem is returning.

Does anybody know if a puff of grayish-blue smoke during cold starts has anything to do with this IACV issue? I've heard it might be PCV valve.

Back to IACV clean-up, it looks like I will attempt a full disassembly and cleaning. The design seems sub-optimal since all crud and debris tends to accumulate in the IACV, but that's just how it is on these Toyotas. I will try to pre-order the seals (thanks for the list of 3 seals, phobang). Smoother transmission shifts might make sense if the IACV is used by the drivetrain ECU to momentarily reduce power during shifts.

Excellent contributions, everybody.

[code58]

Judging from the number of responses, IACV seems to be the number one reliability issue for these Lexus/Toyota V6s. Our ES300 had it too. Not wanting to tear up too many seal gaskets or screws, I tried the short-cut method of spraying the pintle area and idle air passage with carb cleaner then WD40 after removing the black solenoid cover. It did not give me a good feeling because the design causes drippings to collect at the bottom of the throttle body where the IACV is mounted. It worked for a few months but now the problem is returning.

Does anybody know if a puff of grayish-blue smoke during cold starts has anything to do with this IACV issue? I've heard it might be PCV valve.

Back to IACV clean-up, it looks like I will attempt a full disassembly and cleaning. The design seems sub-optimal since all crud and debris tends to accumulate in the IACV, but that's just how it is on these Toyotas. I will try to pre-order the seals (thanks for the list of 3 seals, phobang). Smoother transmission shifts might make sense if the IACV is used by the drivetrain ECU to momentarily reduce power during shifts.

Excellent contributions, everybody.

Could be wrong but I don't think the IACV would have anything to do with the reduction of power on the shift. I think that is all done through the PCM. The IACV should only come into play in idle. It's not really so bad to pull the IACV off and clean it right. Then it will last. One other suggestion I have is keep the WD-40 and the carb cleaner away from the intake area completely. We used to be able to get away with that kind of thing, but no more! With all the sensors and other sophisticated systems, you can easily wipe out hundreds of dollars worth of stuff in a heartbeat with the wrong stuff. I would suggest you use ONLY the products that are made for a specific purpose- don't substitute- AT YOUR OWN RISK.

The puff of blue smoke is NORMALLY valve guide seals. The oil runs down the valve stem past the worn seal and sits in the cylinder area when it's started. That's why it only takes a couple seconds to burn it off and no more smoke. Have you ever changed the PCV valve? That shouldn't cause your problem, but it is important to keep it in good operating order. If it doesn't "rattle freely" when you shake it (obviously you have to remove it 1st.), time to replace, but use quality, don't use Fram! Good Luck!

[tedp]

2000 ES 300 WOULD NOT HOLD IDLE...DIED OUT AFTER RELIEVING THROTTLE...VERY FRUSTRATING-->NO OBDII CODE. JUST USED THIS PROCEDURE (HAD SOME TROUBLE LOOSENING A COUPLE OF SCREWS; REALLY TIGHT) PICTURES HELPED TREMENDOUSLY! STEP BY STEP INSTRUCTIONS FANTASTIC! LEXUS NOW RUNS LIKE A "LEXUS"! THANKS TO ALL!

[jmwgomz]

does anyone have the part number for the IACV. I just want to know if it's the same part number as the 01 highlander. It's ~$50 cheaper from a toyota dealer than lexus.

[Fizzled]

Thank you VERY much for this thread! I found this forum searching google for ES300 no start/starts only with accelerator and came across this page.

Spent 1.5 hours in pitch black with friends holding flash lights fixing this thing, followed the directions, works like a charm!

Idle post repair was rocketing to 3.5k RPM which was rather concerning considering the throttle stop was adjusted all the way lax.... however, ECU seemed to figure it out and lowered it to normal after a several minutes of idling and a trip around the block and subsequent restarts have been normal (at least, that's my theory anyway).

I should note that this car isn't mine and I performed this repair for my friend (who's hit bad times with this economy and I'm the closest thing to mechanically inclined around, however my experiences are limited to motorcycles mostly... none of which I've ever had had these IACVs).

I did find removing the TB assembly essential for this repair. I tried one of the 4 IACV screws and felt a lot of resistance and just instantly reached for the locking pliers, nothing but a marks from the marks from the plier jaws on the hardware and they came out no problem.

My Friend and I thank the OP and everyone who's contributed to this thread for all the helpful hints and suggestions!

[tonyblue83]

I performed this procedure on my 2001 ES 300 about 3 weeks ago, and I must say that I have not had any problems starting my Lexus since then, this thread has proved to be invaluable and every ES 300 owner should have access to this ASAP. I admit I was a skeptic before trying this, I had actually had it set in my mind that I would be going to the dealership to have this problem resolved, but basically I was able to get this fixed with some help from my father for FREE! I cannot credit and thank the originator of this thread and everyone who helped contribute to it, I thank you ALL very much B)

[99lexus]

Thanks.

I have 2 questions before starting the job in my 99 ES300:

1. After using the Craftman Bolt-out, will the screws still useable or I need new screws?

2. If I have to replace the screws or want to use bolts to make future job more easily, how can I find the correct size?

Thank you!