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

[kimo]

This morning I followed your instructions and did the IACV cleaning. Thank you for the tips, it made the job go real smoothly. Like one of the others said, I removed the black coil after I had the throttle body off of the car. made it easy to keep track of the brass washer inside there. I only had one screw that didnt want to cooperate, the lock pliers did the job. It did seem that the control mechanism was a little gunked up and not turning as freely prior top the cleaning. Car starts and runs smooth....thanks again...KIMO

[fernandowong]

For someone with no experience with fixing cars and less than handy by nature, it took about a day's worth of work following these instructions. My Lexus is now running like new, save me a few hundred dollars, and learned quite a bit about the inner workings of my vehicle. Thank You!

Two warnings for people like me though:

- Don't reuse the existing throttle body gasket. It took me so long cuz I had to take it apart many time as it kept on leaking coolant. Just buy a bottle of instant gasket from your local auto shop.

- Putting the throttle body back together is pretty tough without removing the little black cover on top. When putting the throttle back together make sure both flaps comes up and down together (in synch). This may be obvious for car gurus, but I kept on having trouble how they were put together after being taken apart.

[lupilulu]

I did this last night and it worked! Thanks to everyone for their advice. We have really saved some money.

Lupillulu

Dayton, OH

[gf-s-rx300]

Thanks for the detailed post. Without this post, my gf would have paid some $500+ at a dealer to get the valve replaced. Me, I cleaned it in an hour.

[MAB]

Thanks again to GoldenStateSilverSport. I am sure your procedure saved me at least $650 considering what dealers here in southern California charge for shop time.

For the benefit of other LOC members who may do this job in the future, I want to share a trick I learned about removing the VERY tight screws (phillips head).

I had tremendous difficulty removing these phillips-head screws (they are all the same size) => the 2 screws holding the coil on the IACV, the 3 screws holding the right throttle body and the 4 screws holding the IACV to the right throttle body. I tried tight-fitting screwdrivers, various phillips tips in a ratchet drive, vise-grips on screwdrivers, etc…but the screws wouldn’t budge. All I was accomplishing was damage to the screw heads.

I was about to give up when I thought of a damaged bolt remover tool (that uses a socket principle) I had seen advertised. My reasoning was that if I could find the correct size remover socket, that the tapered, spiral-flute sockets would fit over and grab the shoulder of the phillips-head screws. Then, I could apply enough torque to loosen them.

I found what I was looking for at Sears. I bought their part number 9-52161 (Craftsman “Bolt-Out”-Damaged Bolt/Nut Remover Set). I also looked at Sears part number 9-52154 (Craftsman “Screw-Out”-Damaged Screw Remover Set) but decided they would do more damage to the phillips heads. Bottom Line…9-52161 did a very nice job. The #4 remover out of this set engaged the shoulder of these particular screw heads well. Note: to drive the remover…I put the hex end of it in an appropriate size socket and used a ratchet wrench to drive the socket.

For those that have not seen them - these remover sockets have tapered spiral flutes inside them, which grab a damaged bolt head when they are turned counter clockwise and release the head when they are turned clockwise.

An afterthought - I was surprised to see these rather large screws in a phillips-head format. Seemed a really poor choice. I have never seen that in an American car…they use hex head instead. Yet, I don’t think this was a mistake because the Japanese designers are smart folks. Therefore, I wonder if the use of phillips-head screws in this application was intentional…to make it that much harder for non-dealer mechanics to work on? The use of these screws make a fairly easy disassembly and cleaning job WAY tougher. It would cause a lot of people to say, "I'll take it to the dealer".

By the way - I did take off the black metal piece mounted on top on the two throttle inlet holes that TunedRX300 asked GoldenStateSilverSport about. It improved access and visibility, which really helped when aligning and bolting up the right throttle body to the left one. I think it made the job easier, overall.

Best wishes to everyone. :D

Thanks TallGuy as well as GoldenStateSilverSport for the great instructions.

I did this job today and it was not to hard at all.

Only thing I would suggest is the same thing that Tallguy suggested in using the Craftsman “Bolt-Out”-Damaged Bolt/Nut Remover Set

part number 9-52161. Made it much easier removing the 3 very tight Phillips head screws that hold the right throttle body in place. I almost gave up until I bought this tool and it took the screws right out. The other 2 screws that hold the black coil to the IAC are a bit smaller than the 3 screws that are holding the right throttle body. I just used needle nose vice grip pliers to loosen 3 of the screws that hold the IAC to the right throttle body and the 4th I was able to get with a tight fitting phillips. Basically these 4 screws and the 2 that hold the the coil to the throttle body are the same size. The 3 that hold the right throttle body are slightly bigger in head diameter and this is were the #4 bolt out tool worked for me. It is to big for the other 6 screws ( 2 that hold black coil and 4 that hold IAC to right throttle body). Also there will be some coolant that leaks out when you take the throttle body out and the 2 hoses that attach to the throttle body. Not enough to worry about though. At least I didn't worry about it. Cleaning was a breeze and don't forget, as most have already stated the small wavy brass washer that sits in between the black coil and the throttle body when you reattach the black coil to the Throttle body.

Thanks again.

:cries: Now tackling the spark plugs on this beast. front 3 are a breeze the back 3 I'm gonna have to read the forum for suggestions. See ya......

[GoldenStateSilverSport]

Nice work, you guys!! I see many of you have fixed this problem on your own. More power to you.

SKPerformance..STICKY ME =) (16,000+ views so far isn't bad)

[Asmodeus]

Nice work, you guys!! I see many of you have fixed this problem on your own. More power to you.

SKPerformance..STICKY ME =) (16,000+ views so far isn't bad)

My wife "informed" me of this problem starting/stalling problem only a couple of days ago. I'm sure she's been telling me about it in her own way for at least a month, but being the guy that I am, I probably dismissed it more to operator error than anything else. No big deal. Then she grabbed me before going to work and told me it was doing the starting/stalling thing, so I got in the car, started it up, it starts, then it stalls, did this like 10 times and the smell of either heavy fuel laden exhaust or actual flooding hit my nose and I thought it was the strangest thing. I was finally able to get it to start, hit the accelerator to at least get it past idle and see what it did. I'd let go and it would die. She had to get to work, so I tried a trick I've used before just to make it happen.

I started it, hit the gas, held it there, hit the brake at the same time, stuck it in reverse, got it out into the street, put it in drive and drove it around the block a couple of times, pull over in front of my house, put it in park, let go of the gas and viola, it ran without stalling. I knew something was wrong, but didn't know exactly what. I thought it was either a faulty fuel pump, maf, or the IACV, but leaning more towards the maf. Then I thought, hey, let me come to the forum and see if any threads addressed this issue. Lo and Behold, I am now here and I will attempt this fix tonight. I've got the tools, just need the cleaner and I'll give it a go and I'll let you guys know what happens. I lurk here way more than post as you can see, but after the transmission problems with the sun gear/shaft spline walking problem that we had on our 2000 rx3000 right after the warranty went bad and $5000 in a new tranny and labor, this site has been invaluable. I'm still *BLEEP*ed at Toyota/Lexus for allowing the transmission designs of this generation car to be on the road without a recall. Plain old BS and they know about it too. Anyway, enough venting

Big thanks to GSSS for the instructions. Just a minor question to you my online IACV guru. Is there a way you could position the pictures in an orderly step-by-step on your original post? I'm going to use the pictures as my guide along with your instructions, but some of the pictures and what steps they belong with are slightly confusing me. No biggie, I can figure them out eventually, i'm just trying to work around the way my brain works. thanks again and I'll let you know how it goes.

edit: I took everything apart as shown. It's nice to be able to bring the laptop down and look at the instructions while i'm under the hood. got the throttle body off (damn those screws were tight). got everything cleaned and put back. turned on the ignition and viola seems to be working... taking a test drive now, will report back in a jiffy.

edit #2: test drive went well, but noticed that water was slightly leaking. I think one of the hoses or clamps is loose. checking now....

edit #3: yup. the squeeze clamp was loose and it wasn't fitting over the hose properly, so I used a worm screw clamp. all fixed. The next time I do this i'm going to replace all of the screws with hex head bolts instead. will make everything easier. Oh, I also replaced the o-ring around the coolant port from the throttle body to the intake manifold. I'm also making gasket patterns for the throttle body to intake from high temp plastic sheet stock just in case.

edit #4: hmmm. i'm wondering what the proper idle speed should be for the rx300. right now it's idling at around 900 - 1000 rpm. I could have sworn it was supposed to be around 750. can anyone confirm this?

[jefflexus]

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 below 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….

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)

[GoldenStateSilverSport]

Nice work, you guys!! I see many of you have fixed this problem on your own. More power to you.

SKPerformance..STICKY ME =) (16,000+ views so far isn't bad)

... Is there a way you could position the pictures in an orderly step-by-step on your original post? I'm going to use the pictures as my guide along with your instructions, but some of the pictures and what steps they belong with are slightly confusing me. ...

Your wish is my command..good luck guys!

[insurer64]

Wow, it looks like many of you are cleaning your IAC valves. Seems like this is a very common procedure like an oil change (that needs to happen every 50k miles or so). Anyways, I have not used the small impact wrench, but i did use the Locking Grip Pliers in my procedure and this DEFINITELY allowed me to get the job done. W/O this tool, I would have been screwed big time. Good luck to you all!

I found that the screws were really tight also. As I was a mechanic myself many years ago, I learned that a little tapping on screws/bolts would sometimes help loosen them, so before you go and try using other devices to remove these's screws, here is what I did and it worked great. I used a good fitting #3 phillips screwdriver and while I was putting a little counterclockwise pressure on the screwdriver used a hammer and taped on the end of the screwdriver a couple of times each screw, then I tried to loosen the screws with both hands, they all came loose for me. As a past mechanic I found this procedure worked for me 80% of the time.

Good luck.

[Russelltw]

I did this a couple days ago and I have not had an idle problem since. I must say, once I got the IACV out, it was quite dirty and I could tell how the valve would stick. After about 10 minutes of cleaning, it looked great. Total time taking off, cleaning, and putting back on, I had 1 hour in it.

Much thanks to you all for the help and instructions. I saved about $350 (local Toyota dealer).

Russell

[1991 Lexus LS400]

Golden State Silver Sport,

I would like join the others to thank you for your detailed instructions to clean IACV on RX300. I ran into rough idle/stalling issue about two years ago. My mechanic cleaned the throttle body and it did not lick the problem. He then suspected that the MAF meter was broken and we replaced it. It did not work either. Finally, we found out that one of the connecting pins to the MAF (there are five in the cluster) was loose. We fixed it and the problem went away.

Yesterday, my car stalled again on the freeway in a stop and go traffic. I pulled off the road and waited a few minutes and was able to get going again and I limped home with one foot on the accelerator and another on the brake at stop light. When I got home I read this thread and went ahead and performed the process per your detailed instructions. However, my car is '91 LS400 and the throttle configuration is different from your pictures. Nevertheless I was able to basically clean out the throttle body although I could not find IACV. Here are my questions:

1. Do LS400's have IACV and if so where is it located?

2. After I performed the process my car idles fine but the idle feels a bit rough, any idea why?

3. After I put everything back together I found there is a black metal ring left. It's about 3 inches in diameter, 1/16" thick, and 1 inch wide. Where does that go? Is that related to rough idle issue?

Thanks again for taking your time to help out other Lexus owners.

Best regards,

Ray

[1991 Lexus LS400]

I found the following shop manual on IACV testing and installation.

index.pdf

[KBRX330]

Great post Thanks!

[ironox137]

I know this thread is a little out dated so I apologize. I'm not mechanically inclined at all but I have been having similar issues with my Toyota Avalon. My issue is on the opposite end though. Instead of low idling, my car surges and idles VERY high (Usually about 3000rpms). A friend of mine helped me flush the system and clean the throttle body but no luck in fixing the issue. Before I "attempt" to preform this IACV cleaning job, does anyone know if this is a possible solution or if there maybe something better to try? Thanks for the help.

-Matt

[lenore]

I know this thread is a little out dated so I apologize. I'm not mechanically inclined at all but I have been having similar issues with my Toyota Avalon. My issue is on the opposite end though. Instead of low idling, my car surges and idles VERY high (Usually about 3000rpms). A friend of mine helped me flush the system and clean the throttle body but no luck in fixing the issue. Before I "attempt" to preform this IACV cleaning job, does anyone know if this is a possible solution or if there maybe something better to try? Thanks for the help.

-Matt

I think you have some kind of vacuum leak. Maybe a cracked or broken hose.

[dpenz]

Very helpful instructions and photos. Thank you all! Here are some additional comments:

I think that a hand impact tool with appropriate Phillips bits is essential for this job. You strike this tool with a steel hammer. This drives the bit into the screw head and also applies a turning force. All of my screws came out unscathed. If you don't have a hand impact tool, use this project to justify buying one! A light tap on the tool is all you need to reset a screw on reassembly, with no worry about your screwdriver "camming out" of the screw. Leave the lock grip pliers in the toolbox.

I removed the throttle body, complete with the idle air control assembly, intact. It seemed easier to disassemble the IAC on the bench. This also makes it easier to keep up with the small parts.

There is no need to cut the cable tie wrap. Squeeze the plastic clip and it will disengage from the bracket.

If the engine is cool, not much coolant will spill out of the hose.

Removing the black metal piece on top of the throttle bodies is easy and makes it a bit easier to engage the right hand throttle body unit when reassembling.

I brushed and sprayed solvent until no more black grunge was evident. I think the main purpose of the cleaning is to free up the IAC valve spindle. It should rotate freely. I added one drop of light machine oil onto the bearing.

When I restarted my engine, it idled at 2000rpm. Yikes! What did I do wrong? Nothing I could think of. So I drove off, and shortly the idle returned to normal and the engine now runs great. Perhaps the (software) controller just needed to recalibrate itself.

This is a very satisfying project, and saves big bucks too. :D

[lexjh]

I found this great instruction yesterday, after my 00 RX300 had the same problem.

Does anyone know why my code scanner reports no error?

I will clean the IACV today after work. Last time it happened is last August. I don't remember clearly but it was probably not so bad. just tried starting a few times...

[Rbeato]

hello, i have been told this is the fix for my car....currently what has happened was one day i was driving and all of a sudden the sound of the intake while under throttle got very loud, sounded as if the intake pipe actually fell off, but it did not, then shortly after that the car would not rev up past 2k rpms then eventually died. i was told this was the mass air sensor so i replaced it, after the replacement of that i reset the ecu, and same thing, car would barely start with out giving it quite a few pumps of gas, then after it starts it idled terribly, and when i would rev the engine it sounded very loud from the intake side and would not rev past 2k.

any ideas what this could be? or if this DIY is the fix i am looking for?

any help would be appreciated

[Fiona2001]

THANKS A MILLION FOR THE VERY DETAILED AND ACCURATE INSTRUCTIONS......YOU SAVED ME A LOT OF "GUESS WORK"!!!! (In addition to $780!)

The only detail I would add, is that when you remove the throttle body, coolant will keep pouring out of the gasket hole on the engine-side. as well as the hose from the bottom of the throttle body that was disconnected. I did not realize this until I had a small reservoir of coolant below the car, at which point I plugged the hose with a screw, and hired my girlfriend (being that it is her car) to hold her finger over the gasket-hole until I was done cleaning the components.

Thanks again, and hopefully I can contribute to this site on another topic to be as helpful as your posting was!

Drive Safe!

[lahermano]

Hi All:

The post is valuable.

However, my rx dosent seem to have idle problem.

Still is that a good idea to clean ? OR don't bother fix it if its not broken ?

Any suggestions ?

BTW, What should be the idle RPM under normal conditions ?

[GoldenStateSilverSport]

Hi All:

The post is valuable.

However, my rx dosent seem to have idle problem.

Still is that a good idea to clean ? OR don't bother fix it if its not broken ?

Any suggestions ?

BTW, What should be the idle RPM under normal conditions ?

Awesome!

It wouldn't hurt to clean it, but why bother if it isn't broken.

[LynntheMac]

Thank you all for the great post. I have a 2002 Lexus ES300 and was having idling problems after my battery died. I left for a trip and didn't drive my car for a few weeks. Once I replaced the battery, the car wouldn't idle properly. It would idle at 50-100 rpms and then the engine would eventually stop.

I found your post, followed the shortcut, and now it runs great again. I had notice before this the idle sometimes would be a little erratic.

The 2002 ES300 only has one larger intake mechanism, unlike the double intakes in the above pictures. I did the following:

1. Removed the stablizer bar connected at either side on the top of the shocks.

2. Removed the plastic engine cover with the V6 lettering (part is just for looks)

3. Removed the large connector hose from the air cleaner to the intake valve.

4. Removed numerous hoses that were in the way.

5. Removed the 4 bolts that fasten the first-stage carborator intake.

6. Then just squirted Carborator/Throttle cleaner everywhere there was a moving part.

My car runs and idles terrific, now.

Thank you all again. Probably saved $400. :D

[goldrx300]

This was a great find. It solved my problem. I used the short cut from Geoff1 and it worked like a champ. I had to use the vice grips pliers to remove the screws as was suggested. I sprayed it out with crc carb cleaner and even sprayed thru the air in take hole until it moved freely. Took about an hour to do.

Thanks so much!

[ace]

Thanks for the pictures and detail steps. That helped a lot.

The following is my SHORT CUT:

I got as far as removing the plastic electrical part and removing the washer.

I was having difficulty removing the rest of the philips screws, when I realised that the protuding magnetic shaft rotates a valve and that the root of the problem was that it was sticking. I could feel resistance to turning it.

So I squirted around it liberally with choke cleaner several times until I could feel it rotate easily and return under its own spring power.

Since the main problem was now fixed I decided to reassemble from that point and save myself the harder work.

6 months have passed without any futher problem. I guess my short cut worked without having to remove the vave body.

Hello Geoff1,

Just wanted to say thanks to your tips above, i too had difficulty removing the 3 screws; but saw your posting and decided to do the same. my es300 has been running A-OK!!! it's idling a bit high though, but no more stoppings!! much thanks again.