I did this about a year ago and regrettably, did not take any photos

but I think I can describe what I did pretty well here:

my Idle Air Control Valve (IACV) had failed, causing the idle to race up high and fall back, over and over, and I was able to verify this by going through the test procedure in the Toyota factory service manual. one or both of the IACV's bearings had seized.

So, unable to afford this $800+ dealership-only part, and not trusting any more of these beasts purchased from ebay that might have the same problem in a month, I decided to do a MacGyver.

I found a student's notebook, with its flexible plastic cover that I instantly recognized was made out of high-density polyethylene (HDPE), this is verified by the resin identification code of 2 inside the little recycling triangle, and I knew this is the same plastic they make gasoline (petrol) cans out of, so I knew it would not dissolve in a gaseous petroleum distillate environment.

the IACV controls some of the air at idle, and some air flows around the valve even at the extreme of motion, so I knew some amount of air would have to flow at all times.

I cut a replica of the IACV's gasket out of the notebook cover, leaving the center hole intact, like as if you were going to try and seal it up.

then to have a small minimum flow to mimic to amount than can always get around the IACV, I used a notebook hole punch and made a single notebook-paper sized hole (approx. 6mm diameter) into my new plastic gasket, and then reinstalled the IACV and my new plastic gasket with all hoses connected, as well as the electrical connection connected so as not to **** off the ECU - lol.

reset your ECU by disconnecting the neg. battery terminal for a few minutes, this way the ECU will relearn your new "homemade IACV"

Voila, a free makeshift IACV to get ya by for a while.

One of these days I will get a used IACV from ebay and install all new bearings in it, as this fix is a bit off of ideal, but for now my idle speed is pretty close to dead on in both summer and winter.

 

where I got the idea for this in my brain

my strongest area of expertise on automobiles is the A/C system, and for any of y'all out there who know about automotive A/C systems, they fall into two types: expansion valve and fixed orifice

the IACV is basically akin to an expansion valve, except computer controlled rather than temperature/pressure controlled, so I decided to make my idle system temporarily into a fixed orifice type system - lol

 

Pics please....

 

no pics (refer to first sentence in the post)

 

pretty cool

I have an issue that im quite certain is coming from my iacv.

When It is cold out, and i start the car after its been sitting overnight , the engine makes a high pitched whine and is clearly starved for air, it then makes a 'click' sound and something relases and it runs perfectly fine again, ive had the intake off and im 95% it is coming from the iacv.

it seems to me something in the IACV is sticking and it takes a moment to warm up and release itself, any ideas or suggestions?

Thanks alot

 

the valve portion of the IACV can definitely get sticky with the same goo that gums up the throttle body butterfly!

 

That high pitched whine, are ya sure that's the iacv and not the starter. Mine does the same thing and I'm pretty sure it's either the starter relay or the solinoid sticking.

 

Hi LScowboy a great solution to a majoy headache. I need to ask if the IACV is stuck closed or partially open you have to do anything to the IAC valve to keep it fully open and allow the air flow coming through the orfice to pass through the valve???

LCAN

 

I was under the impression from your earlier post that you have a model year 2000 LS400

1998 and newer LS400 do not have IACV

 

I don't didpute this one bit however on the RH side of the throttle body opposite the TPS there is a housing which has a port into the throttle body just under the small plate I mentioned before. I assumed this was some type of idle / mixture control device. So if there isn't any IACV on the 2000 L400 what next would you suggest I take .

LCAN

 

just to supplement this thread:
http://www.planetsoarer.com/IAC/iac.htm

referenced from:
https://www.clublexus.com/forums/per...rol-valve.html

 

Thanks for the link concerning the IACV repair procedure a great professional pictorial and percise discriptive procedure. Very well done and most informative.
I fully appreciate all your efforts.

LCAN