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

[iamviolet]

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!

thanks for the post works great.. although I took the shortcut and just sprayed the carb cleaner in the vacumm hose while it was running... shhhh

[rtfl]

Thanks for this great post!

Despite all the warnings about the wavy washer, I did not see one when I removed the black electric coil housing. Does anyone know where to get a replacement? I cleaned the iacv following the step by step but it did not fix my idle problem (cannot hold idle without applying gas). Also, is there supposed to be a gasket on the right TB?

[code58]

Good for you Mr. F- I'm glad to hear of friends helping friends. You never know when you help someone you don't even know when you'll make a new friend for life. Wish more of the world was like that- wouldn't it be a great place to live? You mentioned one thing that shows common sense (really no such thing), sense at least, and that is to use vise grips on the screws. My preference is the needle nose vice grips, but any will work actually. I have both sizes of the impact drivers that also work well. Many people think the screws are tightened really tight. That's not really true. The Japanese have always used really soft screws and bolts that tend to "grab" the adjacent metal when a really hard bolt or screw wouldn't. Thanks for reminding people about the "vice grip cure" for "clingy" soft bolts and screws.

[code58]

Thanks for this great post!

Despite all the warnings about the wavy washer, I did not see one when I removed the black electric coil housing. Does anyone know where to get a replacement? I cleaned the iacv following the step by step but it did not fix my idle problem (cannot hold idle without applying gas). Also, is there supposed to be a gasket on the right TB?

rtfl- There are definitely supposed to gaskets on both the air intake tubes. I assume you mean where the intake tubes bolt to the throttle body. That may be the cause of it not idling. How long has the non-idle situation gone on? You can check the electric coil with and ohm meter. The manual says the resistance should be from 17.0-28.5 depending on whether it's cold or hot but I believe I have read that is a mistake in the Lexus shop manual. When I cleaned it on my DIL's RX it worked perfectly afterward while one side read 2.0 ohms and the other side read 59.0 ohms. I replaced it anyway because my DIL was going to be a long ways from home in a vulnerable position. With it off the car but the plug connected, watch the cylindrical opening while you have someone turn the key to "on" (NOT START). the cylinder should move to fully closed, then fully open and back to rest at half open, all in 0.5 seconds. (1/2 sec.) If you replace the gasket that is missing and check and see that the valve DOES operate as it is supposed to (off the car), I'll send you one of the wave washers. Some have said it works fine without it. I don't know exactly why it is there. If it doesn't function properly with that test, you'll need to replace it anyway, and the new one will have a washer in it. Let me know how you come out.

[rtfl]

Thanks for this great post!

Despite all the warnings about the wavy washer, I did not see one when I removed the black electric coil housing. Does anyone know where to get a replacement? I cleaned the iacv following the step by step but it did not fix my idle problem (cannot hold idle without applying gas). Also, is there supposed to be a gasket on the right TB?

rtfl- There are definitely supposed to gaskets on both the air intake tubes. I assume you mean where the intake tubes bolt to the throttle body. That may be the cause of it not idling. How long has the non-idle situation gone on? You can check the electric coil with and ohm meter. The manual says the resistance should be from 17.0-28.5 depending on whether it's cold or hot but I believe I have read that is a mistake in the Lexus shop manual. When I cleaned it on my DIL's RX it worked perfectly afterward while one side read 2.0 ohms and the other side read 59.0 ohms. I replaced it anyway because my DIL was going to be a long ways from home in a vulnerable position. With it off the car but the plug connected, watch the cylindrical opening while you have someone turn the key to "on" (NOT START). the cylinder should move to fully closed, then fully open and back to rest at half open, all in 0.5 seconds. (1/2 sec.) If you replace the gasket that is missing and check and see that the valve DOES operate as it is supposed to (off the car), I'll send you one of the wave washers. Some have said it works fine without it. I don't know exactly why it is there. If it doesn't function properly with that test, you'll need to replace it anyway, and the new one will have a washer in it. Let me know how you come out.

code58 - Thank you so much for your detailed and helpful response. After testing, fiddling and reinstalling the TB intake tubes with the proper gasket, everything is back to normal! I don't think I need the washer, but really appreciate your offer to send one.

I can't express enough my gratitude to all the knowledgeable people who contribute to this forum

[code58]

Thanks for the thanks Rtfl- glad you're back in business. I can't figure why the wave washer is there either, but I do remember at least one who said it worked fine without it. I think the lack of a gasket was probably the problem.

[Chris G.]

I was a little reluctant to tackle this job being (a young) 82! But, the car stalled at idle and I was 10 miles from my service dealer, so I decided to tackle it. Also, hearing that it would cost anywhere from $400-$600 gave me the incentive. Here's a summary of my experience:

First the hose clamp on the back hose was put on backwards and the screw slots were not accessible with a screwdriver, so with the help of my wife's smaller hands, we used a socket to loosen the clamp enough to turn it so that we could use the screwdriver.

Secondly, we were unable to disconnect the black electrical cable, so we proceeded with it connected.

We were very careful removing the two screws to the black coil from the IACV so as not to lose the small wavy washer. As it turns out, that washer actually rests well inside so if care is taken, it will stay there.

We sprayed around the shaft of the IACV until it rotated freely and then reassembled (reversing the hose clamp, of course).

Started up immediately and idle is smoother than ever.

I must thank my neighbor in San Jose for this great post! :) :)

[code58]

Chris- Always glad to hear success stories. I'm also glad to hear that you were not intimidated by age. I'm not going to state mine but age is a state of mind and there are "young" and "old" at all ages. My wife went back to her aunt's 100th B'day party a few months ago. She had just renewed her DL a couple of weeks before, she looks 60 and has the handwriting of a 25 yr old!!! You're only as old as you think you are! Glad you're not intimidated by computers, or IACV's Isn't life great?

[amc1]

Did this on a 2000 ES300 a couple of days ago. Was intermittently not starting without holding gas down. Now works perfectly. Quite a mess, but worth the $200 savings

140k on the car and on the iacv. Engine only has 49k on it due to being replaced at 91k due to sludge/bent rods and damaged pistons. (Thanks Lexus for the $9k engine)

[code58]

Trust me, you saved more that $200., even in Atlanta. Very few if any shops want to take the IACV off and clean it. A dealer definitely won't. They have all become "parts changers". No repairing anything any more, just throw a part at it. I would say at least $450.-$500. if you had taken it into a shop.

[pdizzle721]

ok. i tried this and it didnt work, BUT thinking back about what you said about the washer that sits in the pencil sized stud, mine was bent, and I wasnt sure if it was suppose to be that way or not, so i left it. should I have replaced it with a flat washer?

My car idles in park at about 1200, and in drive about 1000, and when im driving and i goto stop, the rpms jump just b4 i stop. Any ideas??

[pdizzle721]

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,

I need your help I have the some prob. I have replaced the o2 senor, cleaned the MAS sensor, iac valce, seafoamed ect. everything BUT the EGR valve. It looks like a PAIN to get to. I have a 2000 es300 to, so ANY HELP would GREATLY be Appreciated. ( on the iac valve, is it suppose to turn back and forth freely? i noticed after and b4 cleaning mine it would stick a little)

Thanks

[code58]

I know this wasn't directed to me, but I'll answer the question you asked. How did you clean it? If you took it off and apart and cleaned it, It DEFINITELY should move freely! It is only turned by the small electro-magnet, which isn't powerful because it doesn't need to be. Any sticking is going to cause it to malfunction. Some guys try and shoot carb cleaner in there and clean it on the car, and actually are successful. That is not the right way to do it and probably won't last to terribly long before the problem returns. I am guessing it didn't get cleaned thoroughly in the round slot valve or the shaft, because dirt is the only thing that would keep it from turning freely.

[code58]

PD- The washer is supposed to be bent. Kinda like a "wave washer". Those that have lost the washer or it wasn't there because someone else had lost it before them have all reported that it seemed to work fine without it. I can't see the reason for it and I say if it works fine without it, don't worry and if you have it and it's bent, you have what you should have anyway. There is a way to test the IACV and the down load should be here or on the other popular Lexus site. Did YOU take it off to clean it? If it is free and you did clean it thoroughly (off the car), maybe it is bad but I would test it for cycling as prescribed because the Ohms test in the Toyota factory manual seems to be in error. My DIL's work perfectly fine after I cleaned it, but the Ohms test tested bad. The cycling test should be the "telling test".

[Cyboss]

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*

[Cyboss]

Thank you for the instruction this will save me time and money...

[yenanlexus]

Do you have pics for iacv for 98' ls400? Thank

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*

[lexiscool]

I thank all for the input for this procedure....

HELP!

I must have done something wrong.......I noticed that when I removed the IACV & Throttle body, the coolant fluid just kept coming out from the hose going into the bottom of the IACV...where I had to plug it with a towel.

Anyway's after, Yes (stripping a couple screws) I got it off and cleaned it thoroughly. Put it back on pretty good, but noticed when I put fluid back into radiator, it was coming from behind the throttle body......WTH

I took the hoses off and electrical connections off and felt behind the throttle body. There is a hole, where something plugs into it.. I don't recall a hose being in there... but it one must go there because the coolant fluid is pouring out of it......I could not find the hose hanging anywhere...any thoughts or diagrams on what is on the backside of the throttle body?

[code58]

Yep, definitely a small coolant hose that goes to the IACV. About 1/4-5/16 hose. Look around, it's got to be hanging there, it goes straight up from the bottom. Before you take the IACV off, you have to drain some coolant out so that it doesn't run out of that hose when you take it off. Probably 2-3 qts I think should do it. You said there was a hole. There should be a tube (pipe) that comes straight down on the back side of the IACV (about 1-1 1/2in long) that the small hose came off of.

[lexiscool]

Okay....I goofed...apparently I did not read carefully enough to catch that there were two o-rings one on the throttle housing and one on the IAC, found them on ground, put them in and no more leaks........

Huge issue is; I still have the same problem. It is idling rough and going to 500 rpm when stopped at a stop light. Everything is put back just right, the IVC whistle clean, there must be another issue. The CEL (Check Engine Light) is still on, and the horsepower seemed to be diminished along with idling rpm's.

BAFFLED....Any thoughts? Tune up with sparkplugs? Does the IVC need replacing?....144000 miles odo.

[code58]

Okay....I goofed...apparently I did not read carefully enough to catch that there were two o-rings one on the throttle housing and one on the IAC, found them on ground, put them in and no more leaks........

Huge issue is; I still have the same problem. It is idling rough and going to 500 rpm when stopped at a stop light. Everything is put back just right, the IVC whistle clean, there must be another issue. The CEL (Check Engine Light) is still on, and the horsepower seemed to be diminished along with idling rpm's.

BAFFLED....Any thoughts? Tune up with sparkplugs? Does the IVC need replacing?....144000 miles odo.

Always possible. Most of the time cleaning does the job but once in a while they need to be replaced. There is a way to check to see if the IACV is working properly. I have posted the procedure before. You should be able to find it with a search either on this forum or the other popular Lexus forum. The IACV should keep the RPM's at a correct (approximately 700 RPM, warm) even if it needs a tune up. Have you had the codes read? If not, have them read at AZ or somewhere that reads them free and report back and we'll see if we can't help you further

[lexiscool]

Okay....I goofed...apparently I did not read carefully enough to catch that there were two o-rings one on the throttle housing and one on the IAC, found them on ground, put them in and no more leaks........

Huge issue is; I still have the same problem. It is idling rough and going to 500 rpm when stopped at a stop light. Everything is put back just right, the IVC whistle clean, there must be another issue. The CEL (Check Engine Light) is still on, and the horsepower seemed to be diminished along with idling rpm's.

BAFFLED....Any thoughts? Tune up with sparkplugs? Does the IVC need replacing?....144000 miles odo.

Always possible. Most of the time cleaning does the job but once in a while they need to be replaced. There is a way to check to see if the IACV is working properly. I have posted the procedure before. You should be able to find it with a search either on this forum or the other popular Lexus forum. The IACV should keep the RPM's at a correct (approximately 700 RPM, warm) even if it needs a tune up. Have you had the codes read? If not, have them read at AZ or somewhere that reads them free and report back and we'll see if we can't help you further

Had the codes read at AZone yesterday.

1...Random cylinder misfire

2...#1

3...#2

4...ICV

5...Throttle Sensor

**then repeats of 1-3

I did some reading, and saw that clean the MAF(Mass Air) could be the cause, gonna do that today.

Then I was going to do a sparkplug change as well. ($13.78 ea. @ dealer) probably will use Azone denso.

I wonder, last week I put in some seafoam for the first time, and now this....any relation??? I've used seafoam in MC before, with good results. I am thinking, maybe it cleaned out so much gunk that it clogged the injectors or somethihing, possible you think?????

Thanks a bunch for helping.

[code58]

My honest opinion is anyone who owns and drives a car (is able to pass the drivers test) in this day and age, that has a car newer than '96 (OBDII) should own a Code reader. The reason I say that is when having problems, you can read your own codes, go online (plenty of good sites), see what the problems are and then cancel the codes and see what comes back up. Often, you may have a flurry of codes come up, and you don't want to take all of those seriously. If the same ones come back right away, you can BEGIN To take them A LITTLE more seriously. I've seen people have as many as 8-10 codes come up- not likely that all of those are actual problems. VERY unlikely as a matter of fact. You can buy the Denso Iridium plugs (what your car came with originally) online for about $8. ea. I believe the Denso's at AZ are platinum for about the same price. The Iridium are a far superior plug. They actually list for about $20. ea. By the way, I recently bought a nice code reader at Costco for $19.+ They originally sold them for about $33. They were a bargain at $33. but they were evidently clearing the last out at the $19.+ That way, you don't have to run to AZ to have 'em read, and can clear and see what comes up without a trip back. Beats a $100.-$200. diagnostic read at the dealer any day.

This site also has a flow chart of what the probable problems and fixes are also. Just wade a little, a lot of good info on that site. http://www.obd-codes.com/trouble_codes/lexus/

[lexiscool]

Okay, have resolution.

After cleaning the IAVC and not getting a good result, I then clean the MAF and still had codes, however after I disconnected the battery the codes went down to the #2 cylinder misfire.

Bought 3 ngk spark plugs (dealer $13.86 ea, Azone $6.99 ea) bought Azone and replaced the #2 #4 #6 plugs accross the front. Ran code check, still the #2 misfire code came up. Obvious now it must be the ignition coil for #2.

Price @ part store $87.00, dealer approx. $189.00

So I did the next best thing, went to salvage yard and bought a OEM cylinder off a low mileage salvage for $25.00.

Installed, and the RX300 is running like a charmed champion.

I think I allowed the tune-up items to go undone for too long.

I read the instructions for the sparkplug changes for the rear three plugs, and I found a new tool at Harbor Freight and Tool that will do the trick. It is a new long socket wrench, that is flat and has a t-bar internal twist handle that can reach two of them pretty easily. Gonna get it and try it, later to complete the tune up.

When I pulled the #4 #6, they looked pretty good, but #2 was fouled badly.

Thanks to the forum and all the inputted knowledge of this area.

[payyourtoll]

looking for a little help..

I have parts cleaned and preparing to re-assemble here, but I cannot for the life of me re-seat the gasket between the IACV and the throttle body! It is too large and bows up no matter how I try to place it in its groove. I thought it might have expanded due to it being so hot out here in FL, so I put it in the freezer for a few minutes but it did not seem to help.

am I the only one who had this problem?