I have a 2003 RX300, problem when starting specially when hot weather. I have seen some post regarding my problem and the majority is cleaning the Idle Control Value and/or throttle body. My question is how to you do the above cleaning, is this where you add chemical with your gas. Please HELP. Thanks.

My Rx300 has exact same problem, so I got read the forum and took out the 2 air intake hoses and the IACV locates right under them. I took out the two screws and cleaned the inside with the throttle body cleaner. The problem went away, so here is the pictures I took (IACV is the black piece with the two screws, one of them has the yellow dot on it).

Hope this help somebody in the future.

Be careful not to strip the two screws when removing them. It is challenging to break the factory torque to loosen those screws so find a very tight fitting screwdriver that will do the job. I am in the middle of cleaning my IACV myself..

I am going to pin this for now so no one should ever have to ask about it.
enjoy.

I have the same problem, it doesnt start right away and currently I am having low idle speeds. I am going to clean the IACV but if didnt solve the problem I think I will start diagnosing the fuel pump.

my friend is in san jose and she is having problems with her es300. I'm thinking it's the IACV from what I can tell, but she is a girl and can't really do it on her own. Is there anyone who could help her out there? I was going to try to PM GoldenStateSilverSport, but pm's are disabled...

Hey I think I am having the same problem with my 2000 RX300 Let me know if you get any helpful replies... Thanks!

I'm having same problem too. On cold start, idle speed is very low or won't run at all without pushing on the accelerator. After warm-up it is ok for the day. Will clean valve and see what happens.

JetPilot

Clean the Valva and it should solve the problem.
Take off the air filter box lid.
Remove the air filter box along with the filter.
Remove air hose which is attached to intake / throttle body.
Remove th valve....note..the phillips head screws are easy to strip so make sure you have the proper size phillips head screw driver.
Clean enitre valve thoroughly with throttle body / carb cleaner.

Re-assemble, and this should help eliminate the problem. If not, check for fouled plugs, stretched line from accelerator to throttle control, or fouled coils.

Cleaned my IACV on a ES300.....worked beautifully. Runs perfect now. Beats $200.00 for a new valve. Thanks for the tip.

We started out attempting to remove the valve in order to clean it...but of course ended up stripping the screws.What we found to work was that there is a little hole where you can actually spray the cleaner into & it works the same without having to remove everything. Our Lex is now working great.

That actually doesn't solve the problem. I did that, and it proved to be only a very very very partial job. There are several little "chambers" inside the IACV that require direct spraying and rubbing w/ Q-Tip or cloth. To be safe, I decided to just go ahead and do the full job. Once I opened it up, I noticed that there are other chambers that the spray-in-the-hole-method CAN'T reach.

The problem will come back for you, as it will for everybody else. But in your case, it'll be a lot sooner.

My 99 RX300 just started having a starting problem. I thought it would be the"starter" but after seeing this post I am wondering if this could be it? My question is: What would be my signal that this is the problem. My car just clicks when I try to start. It does not do it allthe time and after reading this, it actually might just be when it is warm outside. If it was this problem would I hear the engine trying harder to start or would it just be this clicking noise? Thanks!

Hello,
I have a 2000 RX300 and it too just started the clicking at start. Sometimes it doesn't do it. I bought a new battery because it still had original, but this didn't stop the prob. Has anyone else had similar issues? It almost sounds like a dieing battery or solenoid, but then cranks right uo sometimes too.
Thanks for any help out there.

Hello,
My 2000 RX is 2wd and I'm having the same starting issues as you. Any luck yet?
Thanks

Had the same problem, followed your procedure and it has worked great since. Thanks for the tip!
Just an obvious warning - I hosed out the throttle body itself as well (it was pretty grimy) with a lot of cleaner. When I reassembled and went to start the car, it hydrolocked. I waited about a half hour and I guess the remaining throttle body cleaner evaporated. Another obvious warning (apparently I am an idiot)- Be careful when hosing out the solenoid and throttle body as the vapors and cleaner get redirected basically into your face through the throttle body itself. That is some nasty stuff.

don't know how to delete a post.

My '99 RX300 started having the warm-start-won't-idle problem shortly after running a tank with STP fuel system cleaner because my gas mileage dropped from 18mpg(city) to 14mpg. Local Lexus dealer wanted over $600 to fix. It took me about two hours to remove, clean and reinstall the Idle Air Control Valve and throttle body.

http://us.lexusownersclub.com/forums/index...c=30723&hl= (Big Thanks to GoldenStateSilverSport)

The idle problem seems to be fixed now and hopefully my mileage will increase.

Hey good job and you saved yourself some big bucks, how does it feel to work for $300 per hour....

Thank's. I had the same problem with the (ICV) on my rx 300. Now the problem is gone!

The thing I found that had the biggest impact on the slow/rough idle problem was the small wave/spring washer in the electric motor of the Idle Air control Valve (IACV).
I had tried all of the cleaning and maintenance actions detailed above and found that it made some improvement but did not fully correct the problem. Then I remembered reading something in an earlier forum stating the engine would not idle at all and stall because the wave/spring washer was left out when the valve was reassembled. So I removed the solenoid/DC Motor component of the IACV and took out the wave washer and slightly increased the amount of bend on the washer (don't overdo it) and therefore putting more tension on the mechanical gate of the valve, therefore providing a dampening effect. I placed the washer back in the housing and re-installed the solenoid assembly and found that it was a little spring loaded when I tensioned the 2 securing screws. The engine now idles correctly and the slow/rough idle problem has been remedied, for now anyway. I will continue to monitor it and post it if the problem returns. All the info I have been able to use from this forum was excellent and I am very thankfull to everyone that has contributed and I hope this little note will also help someone out else out there. Cheers

You can fix this obnoxious problem yourself, but you'll probably need a repair manual to know what must be done, i.e diagnostic and repair procedure.

My 2002 RX300 seems to have this problem: yesterday while starting it when it was warm, it would not stay at idle speed and died. I had to rev it to keep it started. Then it ran OK.
It happened again from cold start today, and happened again from warm start today - it can't remain at idle after start.
It's going to the dealer - still under CPO warranty.
Thanks for the info on this thread
-Dave

I have a 2000 RX300 also. I don't have a problem starting at all. What happens with me is that when idling at a light or whereever, the RPMs drop by 100RPM or more and makes it feel a little rough. If I shift to neutral or park, the RPMs go back up.

While under warranty, I brought it to the dealer but they didn't find a solution even though they tried a few things. The Dayton Lexus guys have been great, no complaints, but would love to fix this idle thing.

Did you try the suggested fix above and did it fix your problem?

thanks

Cleaning the IAC valve could very well fix that problem.

I figured it out. Removed the lower portion of the #2 throttle body to perform the cleaning.

Ok, all I have read so far is that the idling low and rough. I have a 2001 RX300. The idling has been high and rough. It seems the car never warms up. The gpm has been poor. Could this be the same problen with a dirty IACV?

jw

I doubt it would have much of an effect on your gas mileage. Does it warm up on the gauge?

Yes, the gauge warms up fine. It's just RPM is high, around 900, and I can feel the vibration. The dealership said it is whin the spec. But it wasn't like this before.

jw

I HAVE 2000 ES300 AND THIS ALSO WORKED FOR MY COLD STARTING PROBLEM ALSO(THANKS FOR THE PICTURE, I WOULD HAVE NEVER FOUND IT WITHOUT IT!!!), THANKS!!!!

THANKS SO MUCH FOR THE PICTURE,IT REALLY HELPED OUT!!!!!

I think youre problem is your battery connector. check it if there's acid build up , clean it real good with wire brush....

There hasn't been a post on this for a while so I thought I would add my story and solution in hopes someone can learn from my experience.

I had the same problem with the idle. Car would not start unless I gave it gas and would die when I let off the accelerator. This is classic Idle control valve behavior. So I looked at AllData and the procedure is to remove the throttle body...I didn't want to go through all that so I looked for another way. Bottom line is that you really do need to remove the Throttle Body to do it right. The IACV is NOT just the black part pictured above...that is just the step motor. The valve is the assembly underneath and has 4 VERY tight screws. I had a hard time removeing them, even with the TB off the car.

Removal of the TB is not for the not so mechanicaly inclined...there are difficult nuts and bolts to reach, hoses to remove (including coolant hoses) and the bolt on the back side (12mm) attaches a bracket and is very hard to reach. The coolant hoses need to be plugged while you have the TB out of the car. Make sure you take a very good look at how the hoses are attached...it is possible to attach a coolant hose to an air port if you are not careful.

Once the TB is off, flip it over on a bench and remove the 4 screws that attach it to the TB. Be careful, there is a rubber/silicone gasket that is somewhat difficult to get back into the recesses when you reassemble. In the valve housing, you will see the actual valve. It rotates to open and close, metering the hole size, allowing air to bypass the butter-fly valves in the TB. Tha is how it controls the idle. Spray with carb cleaner until it is clean and the valve rotates freely. There is some freeplay between the valve shaft and the magnetized head. I was concerned that this was an indication of failure, but when reassembled, it worked fine.

Give the opening in the TB a good cleaning. You may as well clean out all the ports where vacume hoses attach. Re assemble the TB.

When placing the TB back in the car, slip the TB over the intalke manifold studs (you should use a new gasket but i couldn't get one over the Memorial Day weekend) and just start the nuts on the studs. Then try to start the bracket bolt (back side of TB). This was a little difficult...you have to do it by feel and it is very tight for your 12mm wrench. Once started, snug tighten. Then back to the intake manifold studs, snug fit first then tighten them to 14 ft-lbs or 200 kg-cm. I would attach the coolant hoses next, starting with the one on the bottom rear. After that, everthing is reverse order.

One last gotcha...it is possible to incorrectly reinstall the black motor back to the valve housing. Make sure the electrical connector is at the bottom of the assembly.

It is a pain to install everything in order to test the car...If you do not re-attach the Mass Air Flow sensor on the filter housing, the car will start and idle...but you will get a check engine light and it will sputter on reving the engine.

This is kind of long, but I spent 4 1/2 hrs today fixing this and wish I had known what I know now...I would still do the job, but it would have been better knowing what I was getting into.

Slider9, give it another try. Just delete all the text and put in your comments.

I found a new iac valve for $130+shipping and my mech. will do the install for $120. Do these prices sound fare?

what he said also there is a real thin round black gasket... don't loose it!!

Thanks so much. I did as you said and it runs great now.

Thanks, I did as instructed and now works better than it has in 50k miles. The vehicle now has 167k on it.

I just performed the AICV cleaning on my 2001 RX300 based upon this writeup. EXCELLENT!!

I told my wife I just saved her $685 on her car and told her she was going to have to give me something in trade......I enjoyed that.

Thanks for this. It saved me "big time"!

For those of you struggling with the screws, an impact screw driver works miracles. I tapped mine with a hammer a few times and they all broke loose no problem.....

Also, the wire cables can be simply pryed from their respective mounts without cutting.

When you say your idle speed is very low, how low is it?

Mines around 600-800 when warmed up and 1400-1600 cold start.

AznMechanic, I have the exact same idle rpm's as you do. Do you condiser 1600 TOO HIGH ? I thought mine was, and am wondering if this is normal ?

thanks !

Does yours go down after starting the car? The best thing is to let your car idle so it can lubricate before you start riding on your car.

I let mine idle for about 10sec-1min depending on how high the idle is.

Usually after i start my engine its 1600 or 1500 and it goes down to 1300 or 1400 in 20seconds and it goes up and down for a bit.

I currently have Castrol Edge 5W-30 as my engine oil which is synthetic so i was guessing because synthetic oils are thinner and gives better lubrication than dyno oil, it allows the engine to rev high easier because its lubricated better.

Synthetic oils allow better lubrication which reduces more friction which results in lower engine temperature

This is my guess XD