CitySlaka

Is there a way to clean the IAC valve cause I don't have 900 bucks.

deanshark

Take it off and spray it with brake cleaner or carb cleaner.

Entropic86

I'd take it off and test it before spraying it with something that could damage it. It isn't intuitive to test either, I thought mine was broke until I figured out exactly how to test it. You can also find them used on ebay or from a junkyard.

Edit: you need to take it off to test anyways

deanshark

I said take it off and spray. Of course it's gonna be off so yes, test it. "If it aint broke don't fix it"
Tell me, how would spraying it with cleaner damage it?

Entropic86

sorry, didn't mean to be repetitive.

It is possible to just spray carb cleaner into the main air hose of the thing without taking it off....In fact, if you could ensure that the valve was open, that might be a safer way of cleaning it.

If you have the earlier version of these IAC valves, part #22270-50010, it looks like it comes apart which would make it much safer to clean. Mine didn't on a '97...So I just tested it and since getting stuck open a bit by carbon buildup wouldn't cause a low idle problem, I didn't mess with it.

I don't know exactly how it would damage it, but I was told by an experienced mechanic that many working IACs have been destroyed by carb cleaner. I imagine the solvent could take all kinds of dirt from one place in the motor/IAC and deposit it in places you really don't want it, like on the commutator, if it isn't a brushless motor....just hypothesis, I really couldn't say exactly what might happen, but on a $500 part, I'd prefer not to find out.

deanshark

Well, being an "experienced mechanic" I have never heard of one being destroyed by any cleaner, if it's taken off and sprayed with cleaner. (which is what was originally said) Here's a couple links, out of so many, that would have popped up if only the search function was used in the first place. (clean IAC valve) Hope these help.

https://www.clublexus.com/forums/per...rol-valve.html
http://www.planetsoarer.com/IAC/iac.htm

JOEYD2008

Deanshark, Maybe you can answer this question - what makes the Idle Air Control Valve (IACV) go bad? I purchased a used IACV from EBay for my 1996Lexus LS400. I tested the ohms and the reading is 22. The manual says 31-61 ohms. I haven't performed any other tests. Would you conclude that the IACV is bad based on the resistance test alone? I opened it up and there isn't much to it (2 bearings attached to a magnet). I sprayed the inside with CRC Electronic Parts Cleaner and the ohms are the same (22). I just can't understand how this piece can go bad. Lastly, do you know of a way to repair it (raising the resistance)?

Your help is greatly appreciated.

deanshark

The second link I posted there shows how to repair it and how it works. And it even has pics.

Entropic86

...Except that the IACV motor/valve on a 97'-00' doesn't unscrew from the rest of the IACV body. It doesn't look like it can be taken apart without a saw/big hammer. I did search, where I found a couple people saying not to spray these IACVs. I agree with them.

JOEYD2008

This is the exact link I used to 'rebuild' my valve (thanks for the link). However, after following the instructions from PlanetSoarer, I still get a reading of 22 ohms. I even installed this valve and the idle still dipped once the engine got warm.

I re-installed the original IACV (it does the same exact thing) - by the way, the 95-97 LS400's have the IACV that cannot be taken apart. The used valve I purchased from E-bay is from a 96 SC400, I believe.

Any help is greatly appreciated.

dvourthis

I have a 97 and just went through this. take it off and test it by running (-) and (+) jumpers to the proper pins, there are threads on here on how to test it. If the valve doesnt move like it should you must replace the part. If it is so built up with carbon that you can see it actually impeding the movement of the valve, and after cleaning said carbon and the valve still wont move, you must replace the part. anything with moving parts will eventually go bad, **** happens. I got mine from rockauto.com and never looked back.

deanshark

Well, if you notice who asked the question on how to clean (CitySlaka) which is who I answered, he owns a 92 not a 97-00. But if he searched in the first place he would have found people who say clean it and some that say don't, it's just an opinion. But anyway, that's my opinion on cleaning it and what to use. I've cleaned a few and I never had a problem. If ya have one that's not working and you're too scared to clean it, then buy another one, and waste your money. What can I say?

JOEYD2008; I would get a used one from the Junkyard, just test it before you buy it. That's the thing with buying something like this used from ebay, you never know what you're gonna get. Sorry to hear ya got a bad one.

JOEYD2008

Well, I finally had a chance to test my Throttle Position Sensor (or TPS). The original TPS was not giving me an Ohm reading. I went ahead and installed a new one. The good news is that by installing a new TPS and adjusting it according to the manual, I no longer experience the 'Throttle Shock' issue. My 96 LS400 no longer bucks when releasing the accelerator at 40 mph (hooray). The bad news is that a new TPS did not resolve my 'low idle' issue.

I still plan on testing the Idle Air Control Valve (both the original and the one I purchased on E-Bay) by removing and hooking up all 6 leads to the battery in order to see if there is any movement (per the manual).

Another Thought - Does anyone know if a bad Mass Airflow could affect idle? The reason I ask is because I tested the ohms on the Mass Airflow and I did not get a reading. My check engine light is not on but that doesn't mean that everything is okay.

Any suggestions are greatly appreciated.

lexusrolex

so I'm having sort of the same problem with my ls400, the idle goes down almost to the zero when i come to a stop, and it comes back up, iv been trying to figure out why it does that, the check engine light was was on, so i checked what it was, the code was for my egr valve, so i got a new one, i put it on and it still acted the same way, so i asked some one on the forum, and they said to clean my throttle body, so i did, i was so dirty i even took off the top intake manifold and cleaned it with carburetor cleaner, so i put everything back and it still acted the same way, so, some one else said, it was going to be my idle air control valve, so i replaced it!, i drove around and the problem is still there, now i don't knw what it cud be, i need some help

Gene01

My understanding is that you can (or will) ruin a MAF (AFM) sensor on 90 - 94 LS400s if you try to clean them with any type of solvent. They use a Karman vortex sensor. 95 and later can be cleaned with MAF cleaner.
Perhaps that is what the earlier reference to an experienced mechanic was about.
Of course, it is completely different from the IACV.