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Ok, a month ago I thought I was one of the many that were experiencing clutch judder. Two months after the judder started (occurred only when the car was cold) I started having erratic idle behavior at idle speed, increase in engine temp (only at idle - never overheated) and then a Check Engine Light. After being a pain in the ass with the dealer we found out the problem . Initial treatment was replacement of the AF sensor (before catalytic converter) this helped but there were still some issues and we discovered that the idle air control valve was filthy! A little carb cleaner returned its function. Now the outback runs like new and no more judder. The engine was not getting enough oxygen at idle (the ICV provides more than 50% of the vehicles air at idle) created a fuel rich environment = poor car performance at idle and startups and fine above 35 mph. So if you are experiencing a clutch judder symptom, your car is around 55K miles or more and you can wrench then clean out your ICV with some carb cleaner and replace the O-ring seal. If you still have problems you can unplug the AF sensor and have it tested separately from the car. This might save you a $1200 repair (clutch replacement). Which I have read a lot people doing a clutch repair and still having judder - meaning it was probably not their clutch in the first place.

Hope this helps some people in saving some time and a lot money.

:)
 

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If this works then you will be my best new friend! Just one thing, where is the ICV (idle control valve) located?
 

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Discussion Starter #3
It is located on the throttle body. It worked for me. Also if you have not done this in a while get a new PCV valve ($3) and make sure your valve covers and spark plug tube seals are not leaking oil (if they are it is $50 in seals for each side). If you wires are over 30K miles change them to with OEM wires from the dealer ($40). I'm at 65K so all this was just time for me to do. But my ICV was filthy you can replace or clean it but it is so easy to take on and off I would try cleaning it (save some $$$ - I think they are $150) and see if it works. Make sure you take of the negative cable from your battery before unpluging wire going to it (just a precaution).
 

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Ok so i just got under my hood and i cannot determine where the ICV is. I ran the engine for a while to see if i would notice anything moving while the idle slows as the engine warms. I didnt. So i turned off the engine and decided to unscrew the lid in the throttle body (1). It started spraying what i believe was engine oil. Not Gas.
I also removed the two cables attached to the throttle body near the throttle cable(2). Could you please explain in detail with reference to the picture where the ICV is? Thanks a bunch!!
 

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Discussion Starter #6
OK I reread you post. Engine was off. Now nothing should be squirting out because the ICV regulates air only (not gas or oil).
 

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02 OB sport, 2.5, 5MT, WRX seats/catback/rear bar, Hellas, Home Despot CAI and roof rack
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sparkbox, thx for posting that tip!

i've noted clutch judder with most sub.s i've ever driven, part of which i believe is due to engagement mechanism springiness for soft engagement....BUT you're right, it is greatly worsened by mixture problems just off idle.

i've also seen a bad o2 sensor cause similar problems altho in that case due to leanness. in a "normal" vehicle which doesn't have 2 o2 sensors that cost a mint, blindly replacing an old o2 sensor often cures jerky clutch or on/off throttle jerkiness...did one on my Jeep and light-throttle driveability improved 400%.

bw
 

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Ok. So matched the fluid that was leaking out and discovered that it was green and by comparing it i found it to simply be coolant. It squirted out because of remaining pressure in the rubber hose. About 10mL in total came out. I removed the valve and like you said there was some crap in it, but not much. Nevertheless i cleaned it out with degreaser (a Q-tip worked nicely), reinstalled it and the engine seemed normal. I just took it out around the block and not a hint of judder!
I would love to say this fixed the single most complained about problem with subi sticks, but the true test will be tomorrow when i take it out on a cold start.
 

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Its perfectly normal from the looks of it. When you remove the lid you will notice three separate compartments. 2 are for the air delivery which are stacked, and the left compartment is for coolant. Run your engine for a while and you will notice that this lid does indeed become hot. Also if you look closely at the pic i posted the hose on the left of the lid, directly north of the red ended hose delivers the coolant.

Ill take another picture witht the cap off sometime.
 

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There are coolant lines that run through the throttle body for cold weather performance. Small 3/8ths or so line going in/out of the throttle body. Brian
 

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Alright so i just took the outback for a spin and i still didnt feel a hint of judder!!! I cant beleive this actually worked but it did. I suppose it could be a temporary thing but i will certainly post if the problem presents itself again.
THANKYOU SPARKBOX! You may have just solved the most incredible PIA(pain in the A**) problem ever.
 

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Discussion Starter #13
I know how frustrating it was for me - I' m just glad the info help another person. The ICV or Idle Air Control Valve Solenoid can be replaced which is the permament fix, however cleaning it out should provide you many problem free years.
 

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Sparkbox and all,

my '97 M/T outback is giving me similar performance - are these symptoms similar to what you were experiencing before cleaning the IAC?

1, 2, 3rd gear are very jumpy when trying to accelerate non-aggressively. Once it hits 4000 RPM the car takes off and seems to run fine until shifted to the next gear and RPM drops to around 2500. Even in gear 4 and 5 if I apply the accelerator I feel a little bit of hesitation. If I pull off aggressively and don't let the tach drop below 3000 then it does better but I've had this car since mile 1 and I know that driving shouldn't be necessary.

Gas mileage I believe is suffering. I get only about 200 miles on a tank. Is this what others are getting for mileage?

I started a thread called "sluggish acceleration" a while back pleading for help and got a lot of advice. The only thing I haven't done from the advice on the thread was replace the O2 sensors on the catalytic converters. The car was just at a dealership for 4.5 weeks for this problem and he assured me the sensors were tested and working fine. I will replace them if it is thought that they may help.

Here is a summary of what I or a dealership has tried:
plugs
wires
clean throttle body (would this include the IAC?)
coil
plugs again
wires again

I want to use this car as my primary driver but running like this and getting the poor mileage is forcing me to use my '86 prelude.

Thanks in advance for any help!
 

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Discussion Starter #15
The symptoms sound similar basically clutch judder happens relative to a cold engine from stop to start mostly in 1st ands 2nd gear. What happens is you end up performing a slower start with the clutch disengaging a lot slower to keep the judder to minimum. Once the car is warm the judder greatly reduces or goes away, but there is still a slight low end power loss and down-shifting is a little more difficult (not as smooth).

The IAC or ICV solenoid is attached to the throttle (between coil and the air filter box), but it may not have been cleaned. When you remove the air filter box you have access to this valve. Cleaning the IAC or ICV is such a simple procedure I would just do it. I like to us Berryman's B12 carb choke cleaner, but I sure any carb choke cleaner will do. If you clean the IAC get a new O-ring to ensure that it seals properly when you re-install it.

However what I would recommend for you....

Clean the IAC solenoid and check the power going to it (should be your batteries voltage). There is a multimeter test for the IAC unit but I don't know the details.

After you clean the IAC you may want to reset the ECM (do the long method where you disconnect the negative bat. terminal overnight). Reconnect the neg terminal in the morning. Start the engine DO NOT TOUCH THE GAS. Let the car warm up to operating temp (middle of the gauge 15 minutes). Turn off engine. Restart engine and drive the car to a high rev in all the gears (so get the speed up a little more and shift later than you normally would). Then after that warm it up when the engine is cold so that your rpm is just below 1K rpm (3-5 mins). Drive the car how you normally would.
 

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Well its been a while now since i cleaned out the ICV and for the first few days there was no judder at all. However after that it came back, but not with a vengence. It certainly is an improvement prior to cleaning the valve.
I also have discover a possible solution to the judder. I was researching and came upon a website that says it can cure the judder by replacing something that the throwout bearing in the tranny slides against. They basically have a steel part that replaces an aluminum part, which tends to get pitted and scraped since it is a softer metal.
 

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ICV cleaning

Ok, I tried cleaning the ICV but mine doesn't look like the picture attached earlier in the thread. What I could find was not very easy to get to so I decided to drop it.

I did reset the computer as Sparkbox described. Once reset, the car ran fine for a few days then resorted back to the jumpy acceleration. After a few days of driving it around, I reset the computer again. This time it ran fine for one day.

Anyone have any ideas why the reset would cause the car to run fine but only temporarily???

Thanks in advance...
 

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can you give us a little more detail on exactly what you mean by jumpy acceleration?

the symptoms i'm having include flat spot in just-off-idle power (which makes engaging clutch smoothly a bear) and if i lift off the throttle, it bogs momentarily when i get back into it....sorta like turbo lag or a sidedraft-Weber equipped vehicle running excessively rich which needs to "clear its throat" before it will run. once the power "catches", it pulls fine.

i'm gonna do plugs/airfilter/IAC valve cleaning/silencer removal this weekend and see what that does to it, and also see what the old plugs tell me on rich/lean conditions.

so much for supplanting the weird old eurocars with a troublefree and reliable jap car.... :banghead: (don't get me wrong, i LOVE the thing and every day feel sorry for those who drive lesser (non-AWD) vehicles.....):D
 

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Jumpy acceleration - when I try to start off from a stop, non aggressively, the car just kind of bumps a bit or seems very bogged down until I get to about 4k rpm. At that point, it seems to take off. Once shifted to the next gear, the same thing. I also often feel like I have to down shift from 5th just to maintain speed on small hills.

since getting the car back from the dealer I have disconnected the battery overnight three times. Two of the times the car ran great right after connecting the battery back. But the problem always returns.

I called the dealer to ask him if he could solve the problem. Am waiting for a response.

Thanks again for any inputs!
 

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Sparkbox-

I called the dealership to find out about the o-ring seals for the ICV. They told me I could not purchase the o-rings seperate from the ICV itself, ONLY the gaskets. Did I use the wrong terminology when asking? Are the gaskets what you are talking about?

Thanks in advance!
 
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