fyremaster

Hello,

I cleaned out my IACV over the weekend. It was quite gummed up.

The problem is, when I was cleaning it and turning it, I turned it too far. At first it wouldn't idle at all when I started it, so I got back in and turned it hard to the left a few clicks, which then made it idle way high. I slowly adjusted it down until it idles at about 500-600 when hot.

The problem I have now is that when it is cold, it idles over 2000 which has me concerned. It does slowly lower as it warms up but that is still too high for me to feel good.

Any tips on how to lower the fast idle without lowering the warm idle?

Thanks.

salimshah

Are you talking about the slug inside the IACV?

It should freely move (1/2 turn or so .. definitely not 360 degrees). The coil around controls its position as needed.

I would say disassemble and check and re-assemble.

Salim

fyremaster

Yes the slug as you call it.

I thought it was really stuck and turned it but I felt it click which really threw off the idle. I tried to click it back which worked but now the fast idle is really fast!

What should it look like when I disassemble that would cause it to idle so fast when cold?

code58

I just went and looked at the one I have here and it has a stop in each direction (doesn't move very far) and it looks like you'd have to really crank on that thing to get it past the stops. I'm not sure even if you got it back past the stops in the right position that it would recognize the stops the way it should. Meaning stop exactly where it is supposed to for slow and fast idle. Those stops are inside where the air passes through. If you took it back off the car and, looking inside where you can see the barrel with the slots in it, if you could rotate it and make sure that the stops in both direction work solidly. Problem is, if you turned it hard enough to go past the stops, it may have deformed the barrel enough to let air past that shouldn't get past, causing the excessively fast idle. You may luck out, or you may need a new one. That's a pretty delicate part and needs to be treated as such.

salimshah

Roger: Since you have one on the bench, can you post roughly how much the spin is in degrees? Estimate would be fine. Posting the result in the DIY link would benefit lot of members.

Thanks

Salim

code58

Salim, it didn't seem very far but I marked it at each end of stop to stop (on the little round "thumbknob", with the black bakelite cover removed) and it appears to be exactly 90 degrees.

fyremaster

Thanks guys. Very strange but it seems to have corrected itself. It now fast idles at about 1100 and hot idles at about 500. No change was made from when fast idle was 2000+. Hopefully it remains that way so i do not have to replace it.

Thanks again for the replies. i will make sure I am MUCH more careful with it in the future.

salimshah

Thank you

Salim

hypervish

I had this same thing happen to me a year ago, except I never actually even removed the IACV to clean it. I only sprayed a ton of throttle body cleaner into the IACV, and the idle in park was at 2200 rpm. It eventually became normal, after I drove the car for a few days.

code58

Hyper,
By the time all that TBC made it's way to the TB, it ought to have been GOOD and CLEAN!

fyremaster

I wanted to update my experience here in case anyone else runs into this issue.

I removed the throttle body to clean and check the iacv since it started idleing low and dying when it was warm again.

Upon removal and inspection of the iacv I found that I had not actually turned the inner parts of the iacv but just the magnet which is easily rotated when removed from the throttle body. This gave me hope that I would not have to replace the part since it was almost $200!

I reassembled and mounted back to the intake and started the fun part of adjusting. This piece was a PITA to get adjusted correctly but it is possible.

Here is how I did it:

1. With the engine COLD so it would fast idle. This part was hard because you have to wait almost overnight to make sure the engine is truely cold enough to be at complete fast idle.

2. With everything connected start the engine for only a very short period. Maybe 30 seconds to allow the ECU to adjust to wide open on the IACV. Then turn off the engine.

3. Get back in and remove the black plastic part of the IACV that controls the magnet.

4. Then the adjusting part. With the assumption that the plastic part is wide open, turn the **** left (closed) or right (open) depending on where the magnet has the **** adjusted. With the engine cold, it should be fairly easy to turn beyond what feels like the stops but really is just rotating the magnet. To check where the ECU will keep it, rotate the **** to the middle then evenly slide the plastic part over the **** and back off. Then feel where it is holding it. Repeat this as needed to get a feel where it is holding.

5. Then reassemble and start the engine. The idle should be high if you adjusted it correctly and open. Let it warm up for a minute or so. Then repeat step 5 but when rotating and adjusting the ****, make sure the plastic part keeps it closer to the middle when sliding it on and off.

6. Last step is to let it run until at optimum opperating temp and adjust one last time making it keep it just above the completely closed position.

Took me a long time to get it to adjust correctly but now after a week, it fast idles around 1400, and hot idles about 700.

Hopefully this will help someone else out if they run into a similar problem and rotate the **** too far when cleaning it!

salimshah

Since it worked for you, great!

The theory behind the IACV rotating part (I call it the slug) is that the coil around it controls its position. The ECU controls the amount of magnetism needed to position the slug. So whatever you do manually, the ecu will figure out and settle at the right spot.

When ever I do the IACV or MAF cleaning, I do reset the ecu and it takes a few days to fine tune.

Salim

code58

Salim,
I agree completely with what you've said. I have never set the "slug" when re-installing the bakelite cover. The computer will "learn" after a while where it should be, regardless of where you set it. Just the computer doing the job it's paid to do. I have the old IACV off my DIL's RX as a precautionary measure, not because it didn't work. I had originally taken it off to clean thoroughly when idle was lost in the middle of an extreme family crisis. I tested it after cleaning (as per Lexus factory manual). It tested bad per the manual concerning the electro magnet. Resistance between B (center pole) and RSC or RSO (other 2 poles) should be: Cold: 17.0- 24.5 Ohms and Hot: 21.5- 28.5 Ohms. Mine read, one side, 2 Ohms and the other side 59 Ohms, and yet when I put it back on, it worked flawlessly, idle hot and cold. I ordered a new one because I didn't want my DIL having problems with it 1200 mi. from home in a crisis situation for an indefinite period of time. It never failed to work flawlessly the remainder of the time it was on the car until I got the new one installed.
The computer always takes a little while to "relearn" all of the appropriate parameters when battery is disconnected or other things are done affecting the computers "learning bank".