DIY IACV clean picture write-up
Driver
Joined: Feb 2007
Posts: 166
Likes: 3
From: Southern CA
Clear explaination of the inner workings of the IACV
The little metal cylinder that rotates the IACV is a permanent magnet. The black housing, with the wires on it, that installs over the IACV magnet is an electromagnet. If the computer applied no voltage to it it would go all the way in one direction. If it applied voltage all the time it would go all the way in the other direction. The computer controls the position of the valve by switching the voltage on and off. The duty cycle (ratio of on to off time) then determines the position of the valve. Therefore, to answer your question, it does not matter what position it is in when you assemble it. The computer will adjust it automatically.
All is smooth with the RX300... I wish I could say the same for the Ford Ranger.
Driver
Joined: Apr 2012
Posts: 50
Likes: 0
From: FL
Thanks again for this great write-up 
I had to do this procedure again to my sons 1997 ES300 because of cold start problems which fixed it instantly. This was the 3rd time in 14 months that I had to this. What is causing this to happen so frequent ?
I had to do this procedure again to my sons 1997 ES300 because of cold start problems which fixed it instantly. This was the 3rd time in 14 months that I had to this. What is causing this to happen so frequent ?
CL Community Team
Joined: Apr 2001
Posts: 16,575
Likes: 1,393
From: Austin, TX
Salim
Driver
Joined: Apr 2012
Posts: 50
Likes: 0
From: FL
Driver
Joined: Apr 2012
Posts: 50
Likes: 0
From: FL
Where does the Air Assist Hose go to from the throttle body ?
CL Community Team
Joined: Apr 2001
Posts: 16,575
Likes: 1,393
From: Austin, TX
You get the air-intake, coolant to heat (in and out plumbing), pcv sends unburnt fumes, and the vacuum line goes out. There maybe a path to the charcoal filter. This is all from the top of my head. Oh the vac line goes too many places [power steering, heat control and power_brake_booster].
Salim
Salim
2nd gear
Joined: Jun 2013
Posts: 2
Likes: 0
From: ca
thank you and i appreciate the time you took. but for a beginner, how do you access the IACV after filter removal? It does not look easy. You go from picture 3 to picture 4 with no steps laying what you needed to do to remove the with the hoses. I'm going to take pictures as I figure it out.
CL Community Team
Joined: Apr 2001
Posts: 16,575
Likes: 1,393
From: Austin, TX
Some folks have replaced the screws with hex-head screws.
Salim
Driver School Candidate
Joined: Jan 2012
Posts: 23
Likes: 1
From: tx
hey guys this thread has helped me clean, & then change, the IACV, but rough idle remains, so i'm wondering if O2 sensor (throwing code) is to blame per my new thread - can a few of you jump over to https://www.clublexus.com/forums/rx-...ml#post8003382 & let me know what you think if you get a chance? any visits or feedback is much appreciated
Driver School Candidate
Joined: Jun 2013
Posts: 46
Likes: 2
From: TN
The little metal cylinder that rotates the IACV is a permanent magnet. The black housing, with the wires on it, that installs over the IACV magnet is an electromagnet. If the computer applied no voltage to it it would go all the way in one direction. If it applied voltage all the time it would go all the way in the other direction. The computer controls the position of the valve by switching the voltage on and off. The duty cycle (ratio of on to off time) then determines the position of the valve. Therefore, to answer your question, it does not matter what position it is in when you assemble it. The computer will adjust it automatically.
I cleaned the IACV in response to trouble codes and rough idle. It did not fix the problem and the codes progressed to show multiple misfiring cylinders, bad O2 sensors, MAF sensor. All the common ones they talk about here. Know what it was? THE OIL CONTROL VALVES (OCVs)! It is the one part on this engine that does not have a feedback loop to the computer so no error codes are associated with it yet when they mess up it triggers all sorts of other codes.
If you are having trouble with your engine and have tried all the "normal" fixes talked about here, change the OCVs and the associated filters! It's the best $200 you can spend. There are posts on the board about how to do this....
FYI, I am a long time reader on this forum and it has helped me solve a bunch of issues with my car so I feel like I should contribute. I will be posting more in the coming days. I have done a few electrical mods to my car (my specialty) and will detail those later (balanced audio aux/ipod input, sat radio installed in overhead sunglass holder and molded in with fiberglass, bluetooth connection for phone thru siad balanced audio input, replaced faulty trailer isolation box in trunk, etc.).
Thank you for this post!
Lexus Test Driver
Joined: Aug 2006
Posts: 954
Likes: 4
From: NY
This is correct answer ONLY IF THE MAGNET DOES NOT MOVE RELATIVE TO THE VALVE! I know this because it has happened to me. I cleaned my IACV last year using these instructions but the magnet is secured to the shaft with epoxy and a screw. The epoxy came loose on mine and the magnet can rotate relative to the valve (although not easily). If I turn it one direction the car will idle around 3000 rpm. Turned the other way the car will not idle at all and die. Somewhere in the middle is the "happy" place. I found it disassembling, turning the magnet slightly, reassembling, and starting. I think I did this at least 10 times. My car has been running fine for the last 18 months like this, although I need to do it one more time because it idles about 50 to 100 rpms slower than the recommended 750rpm.
I cleaned the IACV in response to trouble codes and rough idle. It did not fix the problem and the codes progressed to show multiple misfiring cylinders, bad O2 sensors, MAF sensor. All the common ones they talk about here. Know what it was? THE OIL CONTROL VALVES (OCVs)! It is the one part on this engine that does not have a feedback loop to the computer so no error codes are associated with it yet when they mess up it triggers all sorts of other codes.
If you are having trouble with your engine and have tried all the "normal" fixes talked about here, change the OCVs and the associated filters! It's the best $200 you can spend. There are posts on the board about how to do this....
FYI, I am a long time reader on this forum and it has helped me solve a bunch of issues with my car so I feel like I should contribute. I will be posting more in the coming days. I have done a few electrical mods to my car (my specialty) and will detail those later (balanced audio aux/ipod input, sat radio installed in overhead sunglass holder and molded in with fiberglass, bluetooth connection for phone thru siad balanced audio input, replaced faulty trailer isolation box in trunk, etc.).
I cleaned the IACV in response to trouble codes and rough idle. It did not fix the problem and the codes progressed to show multiple misfiring cylinders, bad O2 sensors, MAF sensor. All the common ones they talk about here. Know what it was? THE OIL CONTROL VALVES (OCVs)! It is the one part on this engine that does not have a feedback loop to the computer so no error codes are associated with it yet when they mess up it triggers all sorts of other codes.
If you are having trouble with your engine and have tried all the "normal" fixes talked about here, change the OCVs and the associated filters! It's the best $200 you can spend. There are posts on the board about how to do this....
FYI, I am a long time reader on this forum and it has helped me solve a bunch of issues with my car so I feel like I should contribute. I will be posting more in the coming days. I have done a few electrical mods to my car (my specialty) and will detail those later (balanced audio aux/ipod input, sat radio installed in overhead sunglass holder and molded in with fiberglass, bluetooth connection for phone thru siad balanced audio input, replaced faulty trailer isolation box in trunk, etc.).