salimshah

IACV is to control the idle with the foot off the gas pedal. It has no impact on when you have your foot on the gas pedal to drive. It may contribute to the mpg when you are idling, but this is a secondary affect. For MPG calculation IACV clean or dirty has no impact.

Salim

jonas's RX

Hi Salim

I am just curious but is there a reason why so many RX300 owners clean their IACV ? Are there many RX 300 owners. Having an idle issue ? I only have 41 K on my 01 and was just thinking of cleaning this ��

Are most of the owners only cleaning them when they have high mileage ?

Cheers

salimshah

First rule of DIY:

Avoid the urge of doing preemptive maintenance.

So if you do not have idle issue, don't mess with IACV.

My observation is IACV needs attention @ 65k miles.

Salim

jonas's RX

Got it

I am one of those owners that change the battery " before it goes dead "

Thx again

salimshah

Tires before they get bald and brake pads before there is metal to metal grinding ....

Joking apart, have the battery tested. Decent battery can last between 2.5yrs to 9yrs.

Salim

rosen71

Is the IACV cleaning part of the Lexus maintenance, or it is just a DIY thing?
As my one was bought from Lexus dealer in Italy with FSH, I couldn't find any traces of someone doing it.
The car is 228000 km on the clock.

salimshah

No. It is not part of regular maintenance. Please consult the owner's manual or call the dealership. If you have idle problem, then this item needs to be serviced or replaced.

Salim

rosen71

That's OK. I don't have idle problems, so will not bother doing it.
Thanx

mrkropp

I have a 2001 RX300 with 175k miles. The car was stalling at idle. I took it to a toyota dealership and they told it would be a $800 repair to replace the IACV, not including cleaning the throttle plate. I asked if they tried cleaning the valve to get it to freely spin. They told me it would be more in labor than just replacing the part. I found the Genuine Toyota part online from another toyota dealership for about $240. Obviously this dealership is trying to stick it to me.

I had the car towed to this dealership. My question is should I try and drive the car 15 miles to a different (independent) shop, or have it towed. I could put the car in neutral at stops while revving the engine. What would you do?

salimshah

The dealership should charge you the following
Labor for Diagnosis
Cost of parts at dealership price
Labor to replace and test
Standby for after repair service if needed

Labor rates are higher at dealership $120+/hr and they may have a flat diagnosis fee.

You can get the part cheaper elsewhere and reduced labor.

I estimate 1-2hrs for labor.

Please understand the dealer would most likely not try to repair the IACV and just replace it with new ... to minimize the chance of after repair service.

Our DIY describes in detail what is needed and also mentions the difficult portion .. removing the screws. You can ask a shade tree mechanic to do it for you or go to half decent mechanic for reduced labor price. DIYs at times can take a turn for bad (risk).

I can not suggest do drive or tow, as there is an outside chance of an accident. You are the best person to manage the risk. With 2 feet I can control the throttle with right and the brake with left [skill learnt with 3 pedal arrangement] .. essentially keeping the rpm around 900 while the transmission is in drive and heavy foot on the brake [no need to put it in N]

Salim

mjpewters

Thank you, all went well until I started back up. Maybe a vacuum leak. Idle was high at 1.5 grand. Then after a brief road trip would go to 2.5 grand and drop to 1.5, back and forth. Checked all connections a second and third time. Could I have broke the valve, or does it seem like a vacuum leak?

salimshah

Vacuum leaks generally do not produce such a large swing in idle.

Salim

siddfynch

Hi All.

Great thread. I came here when searching for possible fixes to my car's stalling problem. In a nutshell, my "new" RX300 is stalling as soon as I shift from P to D or (especially) R after a cold start. Idle seems normal otherwise, though I do an odd surge cycle every 90 seconds where the RPMs drop 100, climb 200, then revert to "normal" of ~725.

Does it seem possible the stalling and/or the surge cycle are an IACV issue? If so, I am going to try cleaning it after picking up the necessary parts.

Baetke

Definitely. You will know for sure when you open up the IACV and try to rotate the valve by hand. If it feels "crusty" at all you need to clean or replace it. What I did on mine was use a small magnet to rotate the valve instead of my fingers to make sure it had absolutely no drag while rotating.

siddfynch

I just performed this service on my car and it immediately appears to have helped several things after just a 10-mile test drive. The IACV was indeed sticky, there was gunk in the throttle body, my PCV valve was fouled, and the breather hose and bellows both had a lot of oily gunk. For all, I followed the instructions in this thread and found it pretty easy. Here's what it fixed:

1. Idle has dropped from 730 rpm to 690.
2. The car no longer shudders and cycles every 60-80 seconds. It's just a nice even idle now, +/- 10 rpm.
3. The car did not want to stall when putting in gear. Will want to test this on a colder start, but am optimistic.
4. My MAF at idle has dropped from 5 g/s to 3.5.
5. For whatever reason, my short term fuel trims at idle are now right around 0. Long term remain in the minus teens.

Lots of great help in this, especially about impact driving the screws before removal, missing o-ring, removing hose below housing, etc. I ran a whole can of CRC throttle body cleaner thru, but disconnected the hose first and had no problems on startup. I did find a copper washer inside the idle valve housing that nobody else mentioned yet - it blew out when I backsprayed it with cleaner and I was lucky to see it come loose before flying out.

Also, I called around to find replacement bolts for the delicate brass screws and was warned that they're brass for a reason - they don't want you to overtighten the screws and have the housing crack if you have a road impact. I chose to reuse the old screws, but optimally i would just replace with OEM next time.

Thanks to everyone that contributed to this fine thread.