Idle control valve

[Stefan]

I am tracking down some problems with my car and as a matter of course I removed the idle control valve to clean it. Looking at the various posts on the subject it sounds like you should be able to push the valve open with a screwdriver. However, even after letting it soak for over an hour in carb cleaner, I cannot get any part of the valve to move. From the pictures it looks like I sould be able to push straight in on the metal flap. But it won't budge.

Should I try to force it? Replacements are really expensive (around $300) and I'm thinking of getting a used one. My car has 110k miles on it and it idles high when warm.

[Loren]

As I recall it rotates like a little door.

If it is stuck or sometimes the solenoid goes bad then you need to replace it.

Have you checked with Sunset Imports (Porsche Parts at Dealer Cost) for a better price?

[Stefan]

Yeah, it sounds like mine is bad. I just wasn't sure if power is required to be connected for the flap to be movable.

I will check with Sunset.

Does the idle control valve being stuck affect the way the car runs when not at idle? I would think it does since the channels from the throttle body seem to always be open to the ICV.

[Loren]

I would think so if it stuck open.

If it were stuck closed the car would not idle at all (no air).

[pk2]

I am tracking down some problems ...Should I try to force it? Replacements are really expensive (around $300) and I'm thinking of getting a used one. My car has 110k miles on it and it idles high when warm.

Loren certainly knows his stuff, I'd add though that if your going to replace, why not try some force first? Ziltch to loose.

My experience with vintage stuff is; If you can get it to move at all by whatever means, even just a little, keep working it back and forth with WD40. Gradually it will move more and more till its at it's full travel. Then keep working it till it smooth and easy.

Nice raps, some heat from a little torch can help…Not in the book I know, but a frozen valve is a frozen valve.

PK

Edited December 6, 2007 by pk2

[Stefan]

It is stuck partly open.

It wasn't budging at all and I pushed fairly hard. I will try some penetrating oil and perhaps some WD-40 to see if I can get it to budge. I am assuming that you can push straight inward to get it to hinge. That is what it seems like from the one relevant picture I have seen. I'll probably end up breaking it but what the hay.

[Stefan]

Success!

I filled the cavity with PB Blaster (awesome stuff) and let it sit for about a minute. Then I put a screwdriver in the slot and turned it. For the first time, the flap budged but barely. I did this about 50 times and it loosened up a ton. I did the same thing with WD40 just for good measure. I used compressed air to get rid of excess lubricant. I put the ICV back in the car and it ran much better and idled lower than before (previously 1100 or so, now at about 900 - still too high).

So I again took out the ICV. I noticed that the flap would only close as far as the point it had previously been stuck. I filled the cavity with WD40 but it was still difficult to force the flap all the way closed. I forced the flap closed, then open and repeated many times. I put it all back on the car and the car is idling excellently.

I took the car on a quick trip down the road and it seems to run smoother but that could easily be my imagination.

Note that the flap doesn't push in as I had incorrectly guessed from the photo in the PDF in this thread

http://www.renntech.org/forums/index.php?s...3120&hl=icv

It actually pushes to the side.

$260 part replacement averted (for now).

Big thanks to Loren and Pk for their advice.

[pomocanthus]

Stefan,

This thread gave me the confidence and knowledge to clean the TB and ICV this weekend. I think the most difficult part was separating the TB from the intermediate piece that connects the intake manifolds. Two of the four hex bolts were blind bolts and you had to be a contortionist to reach them while at the same time laying on the trunk deck and working underneath the folded up convertible top. TB wasn't that dirty compared to other people's pics but ICV had a lot of hard carbon build up on it. Toothpicks and Q-Tips were great for cleaning this part along with the CRC cleaner. You mentioned above that the ICV was partially open after many cleanings you finally managed to get it to close. Mine moved with relative ease even before the cleaning but only closed to a certain point (~ 3/4 way closed). Is it supposed to be closed all the way as your thread implied? I installed mine with this "opening" and it seams to be idling fine.

A few more notes. My TB wasn't all that dirty but after cleaning it made a world of difference on the throttle response. There is no longer the slight hesitation in 2nd gear. Overall it was very worthwhile project to do. My next project will be replacing the OAS. The J-tube that I removed to get to the TB had a good amount of oil in it (3-4 drops from each end). I haven't had a good look at the bellows but the OAS itself is caked in dirt. Dirt that is stuck to old oil. This DIY has given me the courage to do the OAS R&R which I hear is far more difficult. Thanks to you, Loren, Tool Pants (did I just repeat myself?), Todd, and others for making this less frustrating.

Now back to my 80K old but rejuvenated '99 2.5.

Hung

[liifesfun]

Stefan

In case your idle is not quite there.

Not sure of where you are at with your AOS in the last 12 months I have done ICV, MAF, Throttle body and got an improvement in idle all the way through the process but had a few periods where it would wonder up and down, 3 weeks ago I did the AOS and now its perfect, rock solid the tacho hardly moves from about 780 rpm.

Sorry didnt document the process any near like I did with the ICV , (your right I should have stated its a sideways push , not a downwards push on the valve) The AOS was a messy job and very hot, so the camera stayed inside.

Bruce

Success!

I filled the cavity with PB Blaster (awesome stuff) and let it sit for about a minute. Then I put a screwdriver in the slot and turned it. For the first time, the flap budged but barely. I did this about 50 times and it loosened up a ton. I did the same thing with WD40 just for good measure. I used compressed air to get rid of excess lubricant. I put the ICV back in the car and it ran much better and idled lower than before (previously 1100 or so, now at about 900 - still too high).

So I again took out the ICV. I noticed that the flap would only close as far as the point it had previously been stuck. I filled the cavity with WD40 but it was still difficult to force the flap all the way closed. I forced the flap closed, then open and repeated many times. I put it all back on the car and the car is idling excellently.

I took the car on a quick trip down the road and it seems to run smoother but that could easily be my imagination.

Note that the flap doesn't push in as I had incorrectly guessed from the photo in the PDF in this thread

http://www.renntech.org/forums/index.php?s...3120&hl=icv

It actually pushes to the side.

$260 part replacement averted (for now).

Big thanks to Loren and Pk for their advice.

[liifesfun]

Hung

RE part open, yes thats right, it doesnt close all the way, from memory if it closes all the way there is no air at all getting into the motor as I believe the throttle body is closed at Idle and the ICV acts as a bypass around the throttle body , I believe in later models the throttle body modulates to perform the idle control, meaning the ICV is not there in latter models, Guys correct me if I am wrong on this latter point.

Re AOS - see my comment to Stefan also on idle.

Happy to answer any questions on AOS as its still reasonably fresh in my mind. (I did post it a few weeks ago)

Bruce

Stefan,

This thread gave me the confidence and knowledge to clean the TB and ICV this weekend. I think the most difficult part was separating the TB from the intermediate piece that connects the intake manifolds. Two of the four hex bolts were blind bolts and you had to be a contortionist to reach them while at the same time laying on the trunk deck and working underneath the folded up convertible top. TB wasn't that dirty compared to other people's pics but ICV had a lot of hard carbon build up on it. Toothpicks and Q-Tips were great for cleaning this part along with the CRC cleaner. You mentioned above that the ICV was partially open after many cleanings you finally managed to get it to close. Mine moved with relative ease even before the cleaning but only closed to a certain point (~ 3/4 way closed). Is it supposed to be closed all the way as your thread implied? I installed mine with this "opening" and it seams to be idling fine.

A few more notes. My TB wasn't all that dirty but after cleaning it made a world of difference on the throttle response. There is no longer the slight hesitation in 2nd gear. Overall it was very worthwhile project to do. My next project will be replacing the OAS. The J-tube that I removed to get to the TB had a good amount of oil in it (3-4 drops from each end). I haven't had a good look at the bellows but the OAS itself is caked in dirt. Dirt that is stuck to old oil. This DIY has given me the courage to do the OAS R&R which I hear is far more difficult. Thanks to you, Loren, Tool Pants (did I just repeat myself?), Todd, and others for making this less frustrating.

Now back to my 80K old but rejuvenated '99 2.5.

Hung

[pomocanthus]

Hung

RE part open, yes thats right, it doesnt close all the way, from memory if it closes all the way there is no air at all getting into the motor as I believe the throttle body is closed at Idle and the ICV acts as a bypass around the throttle body , I believe in later models the throttle body modulates to perform the idle control, meaning the ICV is not there in latter models, Guys correct me if I am wrong on this latter point.

Re AOS - see my comment to Stefan also on idle.

Happy to answer any questions on AOS as its still reasonably fresh in my mind. (I did post it a few weeks ago)

Bruce

Thanks Bruce! I will start AOS R&R after New Years and will take you up on your offer. I will try to take some pics to post but spacing seems tight.

Hung

[Stefan]

Thanks for the tip. I had already replaced the AOS before doing any of this cleaning. As I have mentioned in another thread, buying $10 hose clamp pliers for the lower AOS hose is the key to keeping your sanity on that otherwise not too difficult job.

It is true that the ICV is obviated by the e-gas mechanism which modulates the throttle body flap to get air into the engine during idle.

Regarding throttle body removal, it is easy for me because I have a 996 engine in my Boxster and it is easy to rotate the intake tube so that the throttle body bolts are all easily accessible. However, I did clean the throttle body when I had the 2.5L engine in. The trick there is to use short wobble extensions. That makes the lower bolts much easier to access.

[Loren]

Yes, there is no ICV on egas cars. Idle control is done through minute movements of the throttle butterfly.

[pomocanthus]

Hung

RE part open, yes thats right, it doesnt close all the way, from memory if it closes all the way there is no air at all getting into the motor as I believe the throttle body is closed at Idle and the ICV acts as a bypass around the throttle body , I believe in later models the throttle body modulates to perform the idle control, meaning the ICV is not there in latter models, Guys correct me if I am wrong on this latter point.

Re AOS - see my comment to Stefan also on idle.

Happy to answer any questions on AOS as its still reasonably fresh in my mind. (I did post it a few weeks ago)

Bruce

Bruce,

I found your AOS R&R thread. There are some good info there but I still have some questions which I posted there. Can you take a look and help? I have a '99 tip and I think you do too ( a tiptronic that is).

http://www.renntech.org/forums/index.php?s...amp;#entry89280

Thanks,

Hung

[Stefan]

it doesnt close all the way, from memory if it closes all the way there is no air at all getting into the motor as I believe the throttle body is closed at Idle and the ICV acts as a bypass around the throttle body

I mostly agree with this. However, I believe that the ICV is supposed to be closed when the car is not idling. So if the door doesn't have the freedom to close the car might not run optimally. But it should idle fine as long as it can close enough to let the right amount of air by at idle.

[dphil66]

Hi guys,

Just thought I'd add my experience here in case it helps somebody... I was having this problem with our '98 Boxster 2.5: (video not my car, but same problem)

http://www.youtube.com/watch?v=1lVGBfjHgAk

Our local Porsche dealer narrowed the issue down to a sticking Idle Control Valve (ICV). They removed it, de-gunked it really well, and had it moving freely before re-installing it just to try that out. The problem went away.

They asked if I wanted to wait for them to get a new part and replace it while they had it opened up, but since I just literally that day handed them almost $1,500 for a new carden shaft on the Cayenne Turbo, I said, "Let's just see how it goes after being cleaned up." A new ICV is about $500 at the dealer, and about 1.5 hours of labor.

This problem had been intermittent - it would occur maybe once a year, and then over the course of an hour or so, the idle revving would be less severe. It might start going from idle up to 2,700, and when it started to abate, it might just go from idle to 2,200....then to maybe 1,800...then it would go back to normal static idle.

This has been a real bugger to diagnose because of its intermittent nature. But there you have it. It could not find a stable idle, and the computer kept trying to compensate with the revving...all because the Idle Control Valve was sticking.

We drive the car daily, a lot, even in the winter (with snow tires and a hard top). So it is truly a daily whip. We bought the car with only 10k miles on it in 2006. It now has about 204,000 miles, and still has the original clutch. Our air-oil separator has just been replaced as well.

OT, but we've never had an RMS leak, most likely because it's driven daily, all year long. And even though she sees plenty of red-line revs, never an issue with the Intermediate Shaft Bearing. Mobil 1 and factory filters every 15k just like the book says. And again, still the original clutch. Except for these two recent issues (ICV and air-oil sep), she's been a real champ.

[Hayestack]

Hi All

I have a 2000 model Boxster S manual with 145000 km.

Starting and idling when cold is perfect however when she warms up, especially in traffic, the idle speed is seldom less than 1100 and on occasions varies erratically between 800 - 2000. Am aiming to clean the MAF sensor and throttle body. Does my car have an ICV? Not sure what is meant by egas models?

Any help much appreciated.

 

[Stefan]

eGas replaces the ICV and all Boxsters 2000 or later have eGas.

 

eGas cars have a computer-controlled throttle (as opposed to a throttle that is connected to the gas pedal via a wire). Because the computer can hold the throttle slightly open to allow enough air in during idle, the car doesn't need a separate valve for that.

 

Cleaning the throttle body will likely solve your problem.

 

[lkchris]

The idle control valve is confusingly named.

 

It does just that, but only at cold startup.

 

Recall the old days when starting a carburetored car when cold?  You pressed throttle to floor to set the "fast idle cam."  The idle control valve is the fast idle cam for fuel injection.  Both are necessary starting a cold car, because first of all this condition requires a rich mixture to overcome the fact a lot of fuel sticks to (precipitates out) the cold intake manifold and doesn't make it to the cylinder.  But, normal idle (throttle plate) settings don't provide enough air to work with the rich mixture, so the amount of air is increased either by the fast idle step or the air bypass created by the idle control valve.  When the engine--specifically the intake manifold--is warm enough, this extra air is no longer needed and the engine gets enough air through the carb or via the mass air sensor ... which now is finally doing its job and not bypassed.

 

Despite the fact the idle control valve compensates a bit for the rich mixture--it keeps the motor running--it's still a rich mixture and there will be unburned fuel in the exhaust ... hence the air pump system that pushes extra oxygen into the exhaust manifold (for 30 seconds) to complete the burn of the fuel there.

 

The idle control valve is closed and does nothing when the motor is warmed up.  The air it bypasses would obviously be unmetered by the MAF sensor, limiting its effectiveness.

 

Direct injection on newer cars clearly addresses the need for "choke."

 

PS:  more "memories" ... Remember the paper hose from the intake manifold to the air cleaner that all the geniuses immediately removed?  Purpose solely to help warm up the intake manifold so car could run smoothly without choke sooner.  Absolutely zero effect on performance after warmup.  There were other systems used to speed intake manifold warmup, some using coolant.

[Stefan]

Actually, the purpose and function of a fast idle cam and the idle control valve are quite different.

 

A fast idle cam reduces air coming into a cold engine to make a richer mixture when the engine isn't hot enough to efficiently vaporize fuel. When the engine is warm, the fast idle cam ceases to function.

 

The idle control valve allows air into a (hot or cold) engine whenever the throttle is closed. The reason the ICV has its name is that the amount of air it lets in is regulated by feedback from the engine speed in order to maintain idle at a specific RPM.

 

[lkchris]

No, Stefan, the fast idle cam provides a fast idle by holding the throttle open a bit.  The cam is part of the throttle linkage.  It's obviously used in conjunction with the choke plate, which is moved either manually or by spring action the spring affected by heat with a term I can't recall, bimetallic perhaps.  The fast idle is set by flooring the accelerator, the choke plate is not.