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Discussion Starter #1 (Edited)
Since it's a little colder outside my Camry likes to idle a little higher when cold and only slightly reduces idle when warm. Cold idle for me is largely temperature dependent, but ranges from 1500-1800RPM - the colder it is the higher the idle RPM. When the engine is warmed up it idles 1200-1500 RPM - a little better but still unnecessarily burning gas. This is likely due to the combination of polished TB and intake - it's probably letting a bit too much air into the engine and since cold air is denser than warm air, well you get the picture...

I tried backing off the idle speed screw but it seems to be as far as it will go that direction

So my question is - having looked at Mr Perkins pictures of the 5SFE IAC valve - it looks like it's adjustable from the elongated screw holes on the bottom side. Anyone tried this and is it as easy as it looks, or will it throw a code and make it idle screwy (I guess there's one way to find out but I thought I'd get some info here first)?

Forgot to mention that I also removed the coolant lines that run to it in an attempt to keep incoming air cooler. This may be my problem...just thought of that...anyone confirm?

Thanks!
 

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Turbo Snail
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yeah having those coolant lines disconnected will make it run at a higher rpm.

I'm not sure what your talking about with the adjustment. If your speaking of the actual electrical connector i removed, it just picks up a magnetic signal and when the motor warms up the IAC will apply voltage to one wire and it will turn the inside to one side or the other.

I dont think there is any adjustment.

One thing I do know is that if you can somehow jam the inside to one side it will idle really low (600rpm). I know this because the IAC I just replaced on the 92 XLE was carbon stuck to one side and it idled like that. After it warmed up there was no problem
 

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Discussion Starter #3
yeah having those coolant lines disconnected will make it run at a higher rpm.

I'm not sure what your talking about with the adjustment. If your speaking of the actual electrical connector i removed, it just picks up a magnetic signal and when the motor warms up the IAC will apply voltage to one wire and it will turn the inside to one side or the other.

I dont think there is any adjustment.
OK in this picture the two screws with the red/orange paint on them MAY BE adjustable - just a theory on my part, looks like the valve can be opened/closed to some degree - may be wrong on this though:

 

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Discussion Starter #5
OK we'll have to remove it tomorrow and make an adjustment and see what happens...if anything...will keep yall posted
 

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2001 Camry XLE 1MZ-FE
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OK in this picture the two screws with the red/orange paint on them MAY BE adjustable - just a theory on my part, looks like the valve can be opened/closed to some degree - may be wrong on this though:
I suspect there is some adjustment, although I can't find any information as to what it is. Mine is a 2000 Camry LE so it might be different than yours, but when you remove those two screws, there is a spring attached to the plate. That spring engages a plastic cylinder that has a cutout in it to allow the IAC cylinder to rotate only within a specific number of degrees. By moving the plate one way or the other it will restrict/allow the cylinder to move more /less depending on whatever that movement is supposed to be.

I had scribed all the pieces on mine before I took it apart, so I don't know for sure what would happen if you rotated the plate/spring one way or the other. I didn't want to fuss with it because the whole assembly is buried under a lot of stuff, and getting to it, to adjust it, once installed would be a royal PITA.


EDIT: Here's a picture of what it looks like.
 

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A camry n00b
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Mine is a 5SFe and AjKalian is right. You can adjust the IAC. I found this out earlier when I actually royally screwed up my IAC cleaning project. I stripped off the Philips screws, broke the throttle body bolt and could not get off the coolant lines. In this whole mess I also managed to screw up my idle.
However I removed the two screws in post#3 picture above and moving the cylinder pivot by hand I was able to bring down my hot idle.
Cold idle hovers around 1000 RPM after settling down(high by 250 rpms)
Hot idle around 750. (after a couple of minutes of freeway driving)
So I dunno how but I am able to play with my idle which is cold screwy right now!
 

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Discussion Starter #9
Excellent! THat's what I thought it was from the pictures - it's a thermostat of sorts which is adjustable. Other IACs should be similar in design to your 2000 model, V6 or otherwise. Will post a DIY this afternoon...Thanks for the nice pics!
 

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2001 Camry XLE 1MZ-FE
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This stuff will make you crazy

I did some testing on the IAC valve by applying 12v to the leads as outlined in the FSM. What I found out is that when the valve is opened, moving the plate on the end of the IAC doesn't do too much. But when the current is applied to close it, it doesn't close all the way. Maybe a .025" gap but the gap can be closed by rotating the plate. Maybe there is supposed to be a gap, IDK.

The other wild card is that the spring might some sort of a thermal spring, that changes tension when it heats up. If so, then the tension could be different depending on whether the engine is cold or warm and the gap could be adjusted depending on the temperature.

And to make matters a bit more confusing, the terminology referring to the terminals is different if you have a 4cyl, or a 6cyl. And to make it even more confusing, there is a typo in the 6cyl instructions. Easy to figure out, but try telling someone to test the IAC by reading them the instructions as printed in the FSM.
 

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Discussion Starter #12
Hmmm....

I know there is supposed to be some kind of gap - that's how the IAC works, but as to how large the gap is and when it should be receiving power/not receiving power - I will simply adjust it and see what happens.

Could theoretically make it MORE adjustable by removing more metal off of that plate but we'll see what happens this afternoon first...
 

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Interesting! Yeah, that coil def looks like a bimetallic spring; a temperature sensor. And it looks like it's bathed in coolant, so it would rotate that gray "cup" in the center with the bowtie-shaped cutout, which looks like it would alter the range-of-motion of the shaft in the center. It sure looks like a way to adjust idle RPM, but in what manner?... Hot only?... cold?... both???
 

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A camry n00b
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Great thread guys...BTW I could adjust both hot and cold idle. In fact you can disconnect the IAC connector and with the car running turn the circular pivot either way.
Keep turning the pivot shaft (obviously circular motion!) with the engine running. Keep doing this until you pull out the IAC connector and the engine should stumble and shut off.
This is how I have set my idle right now.
And Perkins is very correct in post #14 above. I have done this on a fully warmed up engine. On a cold engine this procedure resulted in a vacuum leaks of sorts!
 

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2001 Camry XLE 1MZ-FE
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Now this is really getting interesting

My hunch that the spring might be thermal related turned out to be correct. Why else would they use a brass spring, compared to the normal blueish spring steel. To confirm that I put the spring in a pan of water and put the pan on the stove and sure enough it moved when heated.

So I decided to make a video of it. Sorry the video is not upright, but I couldn't figure out a way to rotate it.

You can see in the first part of the video how as temperature rises the spring rotates. I had to give up taking the video at about 150 degrees, because it got a little hot holding the camera right above a pot of boiling water.

But after the water got to boiling I took a close up pic of the position of the the spring.

The last part of the video is when I poured some cold water into the pan, and you can see the temp drop and the spring return to the 12:00 position.

How much more complicated could they make this thing. You have two coolant lines going to it. There is a vacuum line in the Calif models. There is a magnetic motor that turns the valve. Now I come to find out that there is a spring that when heated changes the position of the valve. If I can find my geiger counter, I'll bet some part of that valve is radioactive and emits gamma rays to be picked up and processed by some other overly complicated system. :lol:




.
 

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A camry n00b
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Thanks AjKalian, you are a very inquisitive science student :)
IMHO this disproves the FSM's claim that idle is not adjustable in camry's (especially 5SFEs).
Also I remember someone on TN saying he could adjust his 5SFE idle using the Throttle Posistion Sensor (aka TPS). I think I may have messed up my TPS also, stupid me I opened the TPS just to supposedly "clean" it up. To my chagrin I found there's nothing to clean!
I screwed the TPS back to the throttle body but I guess its gone out of alignment. Is it possible? Has anyone tried this?
 

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2001 Camry XLE 1MZ-FE
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IMHO this disproves the FSM's claim that idle is not adjustable in camry's (especially 5SFEs).
Also I remember someone on TN saying he could adjust his 5SFE idle using the Throttle Posistion Sensor (aka TPS). I think I may have messed up my TPS also, stupid me I opened the TPS just to supposedly "clean" it up.
When I removed the Throttle Body and the IAC for cleaning the first time I did this, I screwed up the idle too. I looked on the throttle body and saw the adjustment screw, and figured it worked the same as a carburetor. So I adjusted it when the engine was warm, but the next day when I started it up the idle went to like 2,500 and stayed there. :eek:

I figured it was time to read the instructions.

Once I did this procedure, the idle worked as it should, both for cold starts and when warmed up.
==============================================

1. INSPECT THROTTLE VALVE
(a) Apply vacuum to the throttle opener.
(b) Check that there is no clearance between the throttle stop
screw
and throttle lever when the throttle valve is fully closed.

(Note: The "Throttle Stop Screw" I thought was the throttle adjusting screw.)

2. INSPECT THROTTLE POSITION SENSOR
(a) Disconnect the sensor connector.
(b) Disconnect the vacuum hose from the throttle body.
(c) Apply vacuum to the throttle opener.
(d) Using an ohmmeter, measure the resistance between
each terminal.
Fully closed VTA – E2 0.2 – 6.3 kW
Fully open VTA – E2 2.0 – 10.2 kW
...............VC – E2 2.5 – 5.9 kW

(Note: This is a very wide range, so I just picked something in the middle.)

(e) Reconnect the vacuum hose to the throttle body.
(f) Reconnect the sensor connector.

3. INSPECT THROTTLE OPENER
(a) Allow the engine to warm up to normal operating temperature.
(b) Check idle speed. Idle speed: 700 ± 50 rpm
(c) Disconnect the vacuum hose from the throttle opener, and plug the hose end.
(d) Check the throttle opener setting speed. Throttle opener setting speed: 900 – 1,950 rpm
If the throttle opener setting is not as specified, replace the throttle body.
(e) Stop the engine.
(f) Reconnect the vacuum hose to the throttle opener.
(g) Start the engine and check that the idle speed returns to the correct speed.
==================================================

So I don't think you can "adjust" the idle speed in the traditional sense. You might be able to change it by experimenting with the fully open/closed values in the TPS. BTW, the above procedure was for my 6cyl, it might be a bit different for the 4cyl.

But I'm betting Mr. Perkins will know the answer for the 4cyl motors. :D


.
 

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Discussion Starter #20 (Edited)
IT'S FIXED!!!!

Turns out that it IS adjustable as I had suspected by loosening the two small screws and doing some experimenting. First pic is where I started from...looks like it is close to midway between stops:




I first tried to turn it counterclockwise to its full CCW travel so it looked like this:



When I did this idle speed jumped to 2000 RPM and surged between about 1600 and 2000RPM with the computer (I guess) trying to compensate for too fast an idle. So I turned it the opposite way to full clockwise travel, and idle went to 750 RPM on the dot!

If you do the "remove-coolant-lines-to-IAC" mod then you will likely need to turn this adjustment plate FULLY CLOCKWISE for normal idle in colder weather - like so (I just inverted the picture here guys):



HOWEVER, I have no idea how it will idle in the summer months :eek: We shall have to wait and see

@ ajkalian

I monkeyed with the TPS last year and it took a little fiddling to get it back to where it wouldn't throw a code every week or so. But, I also have the MAP sensor enhancer which I'm sure complicated things with the computer as well. Works well now! My gas mileage is acceptable for now and power is, well, it's a 5SFE so what do really expect outside of a turbo or S/C:lol:
 
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