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

[hugo2648]

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 loose this washer. Take it and put it aside so it doesn’t fall off when you continue on in the next steps.

I am really worried. I cleaned out the IACV and my RX300 seems to be idling perfectly. But you talk about this washer. All I saw was an O-Ring when I removed the black coil. But when I moved the car, I saw an approx 1/2 inch wavy brass washer on the floor. Is this the washer you are talking about ? How does it go on the magnet ? Just sits on the stud ?

[GoldenStateSilverSport]

Glad I could help fellas! If it helps you save a couple hundred bucks and a trip to the dealership, I'm all for it. I haven't been as active on this forum ever since I got my 07 GS350.

Hugo - I believe you are correct. the wavy brass washer just sits on the stud. My apologies, I did this procedure about a year ago, but from what I can recall, I remember seeing a brass washer sitting on the stud as you mention.

[GoldenStateSilverSport]

Your directions and pictures became real handy for my when I did this on my wife's '99 Lexus RX300 over the weekend!

Thanks!

Here are several things I found can improve this DIY.

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2. Use latex gloves to help with the clean up (which I see that you use in your pictures... but I think it's worth mentioning).

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Added the latex gloves to my DIY. Thanks for the suggestion!

GREAT JOB, GoldenStateSilverSport. ThankYou.

I noticed some misspellings (like host instead of hose, loose instead of lose and not instead of note) so I made corrections in the text below...just in case it is still possible to make those corrections in your original post. I am very new to LOC so don't know if that is possible or not.

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Fixed the misspellings here...Thanks for catching this.

[brandondiem]

I experienced a brief rough idle this morning after the car warmed up. Is was a foggy morning and I soon headed for home to swap cars before I stalled in Boston traffic. I thought the MAF Sensor might need a cleaning but this throttle body cleaning may do the trick. My only concearn is that my check engine light went on during my ride home. HAs anyone experienced the rough idle problem that triggered the check engine light?

[tmastres]

I experienced a brief rough idle this morning after the car warmed up. Is was a foggy morning and I soon headed for home to swap cars before I stalled in Boston traffic. I thought the MAF Sensor might need a cleaning but this throttle body cleaning may do the trick. My only concearn is that my check engine light went on during my ride home. HAs anyone experienced the rough idle problem that triggered the check engine light?

If the idle is very rough you may have experienced coil failure, that usually triggers a CEl. Search the forum for "coil failure" and see if any of the symptoms are similar. I never noticed the CEL on when I was having the rough idle due to the IACV.

[brandondiem]

I experienced a brief rough idle this morning after the car warmed up. Is was a foggy morning and I soon headed for home to swap cars before I stalled in Boston traffic. I thought the MAF Sensor might need a cleaning but this throttle body cleaning may do the trick. My only concearn is that my check engine light went on during my ride home. HAs anyone experienced the rough idle problem that triggered the check engine light?

If the idle is very rough you may have experienced coil failure, that usually triggers a CEl. Search the forum for "coil failure" and see if any of the symptoms are similar. I never noticed the CEL on when I was having the rough idle due to the IACV.

It was odd. I was at a stop light and the car shuttered a bit , and the RPMs dipped. I put the car in nuetral and gave it some gas and sped home. I have been trying to get to the garage to get the oil changed for the past 2 weeks. So I checked the oil this moring while the motor was not warmed up. the dipstick was low. I wonder if the oil had anything to do with it? Wouldn't the oil presure gauge go off it the oil was low?

[tmastres]

It was odd. I was at a stop light and the car shuttered a bit , and the RPMs dipped. I put the car in nuetral and gave it some gas and sped home. I have been trying to get to the garage to get the oil changed for the past 2 weeks. So I checked the oil this moring while the motor was not warmed up. the dipstick was low. I wonder if the oil had anything to do with it? Wouldn't the oil presure gauge go off it the oil was low?

Unfortunately without a true oil pressure guage you're left with the idiot light that simply warns of very-low or lack of oil pressure, too late gnerally to do anythingn about it. any ime you check the oil it should be warm and on a level surface. I'd say the stick shoudnt be dry when its cold certainly but it could easily be at the low line and still be fine when warm.

How does the car run now?

[brandondiem]

It was odd. I was at a stop light and the car shuttered a bit , and the RPMs dipped. I put the car in nuetral and gave it some gas and sped home. I have been trying to get to the garage to get the oil changed for the past 2 weeks. So I checked the oil this moring while the motor was not warmed up. the dipstick was low. I wonder if the oil had anything to do with it? Wouldn't the oil presure gauge go off it the oil was low?

Unfortunately without a true oil pressure guage you're left with the idiot light that simply warns of very-low or lack of oil pressure, too late gnerally to do anythingn about it. any ime you check the oil it should be warm and on a level surface. I'd say the stick shoudnt be dry when its cold certainly but it could easily be at the low line and still be fine when warm.

How does the car run now?

the oil level is ok. I did clean the throttle body & made a mess of the driveway leaking coolant. The car seems to run

smooth and idle a bit high. I still have the CEl on so I will reset and see what happens. If it is not off after the reset I will be taking to my mechanic to troubleshoot the codes.

[rx300scott]

It seems the biggest problem is getting the screws loosened. Has anyone tried a small impact wrench with a Phillips bit, or would that harm the valve?

Thanks!

[edbro]

It seems the biggest problem is getting the screws loosened. Has anyone tried a small impact wrench with a Phillips bit, or would that harm the valve?

Thanks!

I used the Craftsman “Bolt-Out”-Damaged Bolt/Nut Remover Set recommended by TallGuy. Works great. (Thanks Tallguy). See his post on page 2 of this thread.

[GoldenStateSilverSport]

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!

[edbro]

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.

So, was the pun intended?

[brandondiem]

I replaced the factory screws with bolts. THis will make any future removal much easier.

[tmastres]

I replaced the factory screws with bolts. THis will make any future removal much easier.

Do you recall the size or # designation of the bolts you used by chance?? Thanks!

[toyo]

I have 204 K miles on my 01 Rx. I have removed the throttle body a couple of times to clean it real good but have never touched the IACV. It idles perfectly. I might have to take mine off just for kicks and see what it looks like. Removing the throttle body is a 15 minute job. I take it off and let it soak in a large pan of gas. Then use a toothbruch and clean it like new. I believe I last did it at 150K miles. Heck, I dropped the oil pan last month out of curiosity! Looked brand new in there Thank God!

[emanon]

Standing Ovation! Nice job. Just finished and what wouldn't idle before is now running like a champ! Just saved me a wad at the repair shop not to mention the hassle factor. Thank you

Chris

[GoldenStateSilverSport]

Standing Ovation! Nice job. Just finished and what wouldn't idle before is now running like a champ! Just saved me a wad at the repair shop not to mention the hassle factor. Thank you

Chris

Nice work, Chris! Doesn't it feel good to get the job done yourself? You put in an hour or so, put he car back together, start up the car and abracadabra..it starts like you just purchased it from the dealership. cheers!

[brandondiem]

I found out what the CEL was indicating- Throttle body posisiton sensor. Does anyone have any insight on this one?

[Davinci]

GoldenStateSilverSport,

Again, GREAT post! did the repair on a '00 RX last night, fired it up and she purrs again without cutting off.

Needle nose Vise grips are a must (unfortunately I missed all the great tips on page 2 &3 of this posting that would have shaved a little time for me)

I hope I am able to return the favor to someone on a future post for another issue.

Thanks everyone again

[revlikcrazy]

Thanks alot for the help. Cars run fine now.

[hansenrk]

GoldenStateSilverSport,

Was having the same intermitten idle problems. Almost took it to the Lexus dealer to get hosed for about 5oo to 700 dollars, but did a web search and found your post. Just finished the job. It took me about 1 hour and 15 minutes start to finish (thanks to your detailed instructions and pics). Seems to run better than new. You were so right about the factory tight screws and the large phillips screw driver. I used a socket wrench with a phillis screw adaptor and it helped in loosening.

Thanks again for the great post.

Bob

[GoldenStateSilverSport]

GoldenStateSilverSport,

Was having the same intermitten idle problems. Almost took it to the Lexus dealer to get hosed for about 5oo to 700 dollars, but did a web search and found your post. Just finished the job. It took me about 1 hour and 15 minutes start to finish (thanks to your detailed instructions and pics). Seems to run better than new. You were so right about the factory tight screws and the large phillips screw driver. I used a socket wrench with a phillis screw adaptor and it helped in loosening.

Thanks again for the great post.

Bob

You bet, Bob! Now take the $700 you saved and take a nice little trip! Cheers!

[acthad]

Great info here, but I am in the cold climates where it gets down to 40 below in the winter. Did not want to take any chances so had the dealer change my IAC on my 99 RX300, but talked them down to $380 to do it thanks to this post! So my hands stayed clean with no screws to battle.

Thanks for Club Lexus and this great post!

[lxcincy]

Never worked on my 1999 ES300 before. Stalled only a couple times immediately after starting before it ceased starting at all, although it turned over fine. Didn't want to spend several hundred, so I tried GoldenState's instructions. Started at a leisurely pace after work, broke for dinner and finished in about 2.5 hours.

I just made sure my phillips drivers were filed down well and took my time with the screws.

Started right up first turn of the key.

Thanks a ton for the tremendous public service, GoldenState!

[kimo]

my wife's 2002 rx300 had trouble starting today, it has about 81k miles. after 6 tries she got it to keep running and drove it home without it dying. Is this the similar problem related to ivac cleaning being needed? hard starting? it always seemed to idle fine so I am not sure, but I will probably clean the ivac anyhow. Thanks for the help, kimo