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Accelerator pedal sticking; throttle body cleaning no help


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I'm beginning to think we ended up with the 03 Outback with every possible issue. I'm getting really tired of hearing "I rarely or never see this on a Subaru." We've had a new rack and pinion put in, a new half axle up front, a head gasket replacement, a coolant hose leak that took four hoses to fix (go OE!), a fuel line leak (really!), and now...

 

... the accelerator pedal sticks likes it's glued. With little symptoms beforehand, one day I just had to start slamming the pedal to get it free. Enough that I was worried about breaking something. After it's unstuck, it works until you leave it for a while. Took it in for a throttle body cleaning ("don't see this much with Subarus" -- yeah, thanks) and helped nada. Diagnosis: need a new throttle body -- $700.

 

So my questions are obvious:

1. Seen this before? (found no mention on here)

2. Any ideas to try before a new throttle body?

3. Can you get one from a junk yard to same some $$?

 

As always, I appreciate any and all help!

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Yes, the later models from what I have heard, do seem to have some issues with throttle cables sticking. I'd start there.

 

Head gaskets are almost an EVERY Subaru thing these days. Yours is just "making the rounds" so to speak. :rolleyes:

 

 

$25 for the cable from a dealer. 37114AE02A

Edited by Fairtax4me
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The mechanic said he played with all the parts and concluded that it was something in the throttle body itself. I don't know what these things look like, but he said it must involve where the cable goes through the shaft. Any photos anywhere so I can understand what is going on? And how to explain that I'd like to try a cable before the whole shibang? Thanks a lot for the help.

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I'm beginning to think we ended up with the 03 Outback with every possible issue. I'm getting really tired of hearing "I rarely or never see this on a Subaru." We've had a new rack and pinion put in

 

Ok - that one really is rare.

 

, a new half axle up front, a head gasket replacement,

 

Completely normal for your model/year.

 

a coolant hose leak that took four hoses to fix (go OE!), a fuel line leak (really!), and now...

 

You never see that IF the hoses were properly removed and reinstalled when they did the head gaskets. I would suspect the mechanic is not skilled in the ways of removing hoses undamaged. Especially if these are the small coolant lines on the throttle body/manifold... heater core and radiator hoses and the water pump bypass should be standard replacement items on a head gasket job. Anything less is borderline incompetant.

 

... the accelerator pedal sticks likes it's glued. With little symptoms beforehand, one day I just had to start slamming the pedal to get it free. Enough that I was worried about breaking something. After it's unstuck, it works until you leave it for a while. Took it in for a throttle body cleaning ("don't see this much with Subarus" -- yeah, thanks) and helped nada. Diagnosis: need a new throttle body -- $700.

 

Unlikely - this smacks of poor mechanical knowledge or outright highway robbery. My guess is that your throttle cable is freyed. And even if it needs another TB - that can easily be sourced used without any fear of problems because "they never fail" and so you would be in business for $35 and the time to R&R the thing (it's 4 bolts and a paper gasket :rolleyes:).

 

So my questions are obvious:

1. Seen this before? (found no mention on here)

 

Never - and I've seen a LOT of Subaru TB's. :-\

 

2. Any ideas to try before a new throttle body?

 

Check for the freyed cable. I think someone may be trying to get one over on you. This sounds like a scam

 

3. Can you get one from a junk yard to same some $$?

 

$50 or less. Easily obtainable. Even if you have to buy a whole manifold it should be around $100 or less.

 

GD

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This may be completely irrelevant because I have no idea how your throttle body is set up, but I had a similar situation with a sticking throttle body. The weird part was, the sticking was sporadic and inconsistent.

 

It turned out to be my own fault. I messed with a screw on the throttle body that looked like an idle adjust screw, but it was actually a screw that kept the butterfly valve in the throttle body from going completely horizontal and lodging itself in the bore.

 

The reason the sticking was sporadic was because the butterfly valve moved freely when the engine (throttle body) was warm. If I let the car sit and the engine cooled, the butterfly valve became so lodged into the bore, I ended up actually breaking the throttle cable by pressing on the accelerator peddle with my foot. The tolerances are so close, the expanding and contracting of the aluminum TB housing, due to engine heat, would "stick" the butterfly valve.

 

Anyway, it's just a thought. Here's a couple pics of a old throttle body I have laying around. Also, you can see the "set screw" that I messed with that allowed all these problems to happen. In the end, I just replaced the whole unit with a JY unit and of course, I never mess with that screw again.

 

IMG_5258.jpg

IMG_5257.jpg

Edited by markjw
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Uh oh. I wondered about that with regard to an idling issue we had before:

http://www.ultimatesubaru.org/forum/showthread.php?t=85699

 

My mechanic at the time in VA was not real familiar with Subarus and turned what I assume is that same screw thinking it was an idle adjustment. He turned it back, but I don't know if you can really get it just right. Is this screw so particular that you have to replace the whole unit after that? If so, dammit. Odd that it took three years to start showing a problem. It did begin with the hard cold for this winter, similar to what you describe.

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when i read the first post i assumed it was sticking open, now i think it is sticking closed.

 

i would adjust ''the screw'' l a little. keep track up how much. and see if the situation improves. it cost nothing and should be easy. maybe start with a fair amount, one revolution or more. if you notice a bad running symptom, move it back half way. depending on how often it ''sticks'' it may take several days to know you fixed it.

 

i feel like i have seen a service manual page that reads""DO NOT ADJUST THIS SCREW''.

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when i read the first post i assumed it was sticking open, now i think it is sticking closed.

After re-reading, I am thinking the exact same thing now as well.

 

I have heard of the cables hanging up and holding the throttle open. But if the throttle is sticking CLOSED it is probably that little adjustment screw. The common way to adjust those type of screws on carburetters was to back it off until you could see a gap between the screw and the "stop", which is that little part that sticks out from the cable bracket for the screw to contact. Once you see a gap turn it in until it just touches, then give it another 1/2 turn.

Now that might not be right for Subaru, but if it helps the sticking throttle problem then you are at least getting somewhere.

 

The main problem with adjusting the throttle plate rest position is that it throws off the TPS reading. The ECU sees the change in throttle position and assumes the driver is pressing the skinny pedal and adjusts fuel mixture accordingly. If it thinks that the throttle plate is too far closed, it may lower idle speed which will confuse the ECU as well.

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The main problem with adjusting the throttle plate rest position is that it throws off the TPS reading. The ECU sees the change in throttle position and assumes the driver is pressing the skinny pedal and adjusts fuel mixture accordingly. If it thinks that the throttle plate is too far closed, it may lower idle speed which will confuse the ECU as well.

 

I never could make mine idle right again. I tried and tried, too. I found one at the JY that still had the undisturbed white dab of paint on the set screw. Apparently the white paint is put on by the factory to let us know not to ever adjust the screw.

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I never could make mine idle right again. I tried and tried, too. I found one at the JY that still had the undisturbed white dab of paint on the set screw. Apparently the white paint is put on by the factory to let us know not to ever adjust the screw.
Disagree. It's easy to get the TPS back again. Just tap the lines and set it to the right voltage. I've removed and cleaned/replaced mine a few times.
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Disagree. It's easy to get the TPS back again. Just tap the lines and set it to the right voltage. I've removed and cleaned/replaced mine a few times.

 

Right. It should only be a matter of adjusting the stop screw back to (or as close as possible to) it's original setting and adjusting the TPS. Reset the ECU and it should be golden.

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It sounds like there are two things to deal with then -- the screw (I can try this if someone can give me a general sense of where to find the throttle body on the car; my manual is buried after a recent move), and also the TPS. I get the messing with the screw, but what's the adjustment for the TPS? And the comment about checking voltages completely lost me.

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I wouldn't start messing with the screw just yet.

 

Follow the throttle cable from where it comes thru the firewall to where it ends on the engine. It is attached to the throttle body. You will probably see two gold colored cams that the end of the cable attaches to.

 

One cam is for the throttle cable, the other, identical cam is for something else like a vacuum actuator for the a/c or something like that

 

I would disconnect both cables. Identify which is the throttle cable and have someone sit in the car and press the accelerator peddle. The lug on the end of the cable should retract. Pull on the lug and see if it comes back out easily. Try that a few times to see that the cable moves freely.

 

If it does, then that's prolly not your problem.

 

Look around the cams. You'll see a screw, looks like the one I posted a pic of. See if it has white paint on it. If it does, I wouldn't mess with it.

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Don't worry about the TPS for now.

 

Get a marker or some whiteout to mark the screw with before you adjust it.

 

Here's the basic Subaru underhood layout.

IMG_0105-1.jpg

This is on my 96. Your 03 might look a bit different mainly a large black box at the back where I have marked in red. You might have to remove the box to get room to adjust the screw on yours. I don't know for sure.

The throttle body is circled in blue and the stop screw is on the drivers side of that.

This is the view from the drivers side.

IMG_0106.jpg

Here you can see the throttle cable and the cruise control cable where they attach to the levers on the throttle body.

 

The screw on mine is visible from the back of the throttle body. Circled in red here.

IMG_0107-1.jpg

There is a lock nut on the screw which has to be loosened first. Hold the screw with a screwdriver while you loosen the nut with a box end wrench.

When you mark the screw be sure to mark the nut as well.

The area where the screw contacts the throttle lever I couldn't get a picture of. This may all be different on your engine but hopefully these pics will help you find the screw.

 

Check to see if there is any gap between the screw and throttle lever. If there is, turn the screw just until it makes contact. Then turn it another 1/4 - 1/2 turn and tighten the lock nut. Start the engine and see how it runs. Let it warm to operating temp and if it is running fine and idle is normal, take it for a short drive to see if the throttle still sticks.

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  • 2 weeks later...

Once again USMB comes through with flying colors (and saves me cash)! I ran this issue by my mechanic as an alternative to going after a new TB and one of the techs standing in the office said "Oh yeah, I know about that. Had to do it on my dad's truck." Tweaked the screw just a little bit this morning and now the action is all smooth again. For the record, since it was important to part of this thread, the final voltage was 0.75. Not sure what that factory setting is on this model (03 Outback 2.5).

 

Two things linger in my mind about this:

 

1. The screw was originally fiddled with in 2007-2008 (can't recall exactly when), but the problem didn't show up until this winter. I find that odd, as we've been through a couple wicked cold winters here already before it showed.

 

2. Just the tiniest adjustment to that screw can apparently result in the butterfly sticking so hard that (in cold weather) the pedal is like a brick wall. Crazy!

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Well - over time the throttle shaft (what the butterfly pivots on) will wear and will wear the aluminium bore on which it rides. Not much mind you - but if things were too close it could become an issue. It doesn't take much to get them to bind and it sounds like your's was on the ragged edge of binding for a long time and finally the shrinkage caused by the cold weather grabbed the throttle plate and wouldn't let go.

 

Isn't it sad that a guy with a computer and the ability to type can diagnose stuff better than the average mechanic?..... I tend to think that's what seperates the superstar mechanics from the horde of monkeys. Basically it comes down to reading, research, and search skills. My list of phone numbers, web sites, and my reading comprehension/typing skills are far more valuable than any tool in my garage. With just those and some start-up capitol I could put a man on the moon. And that's only about half "joke" too.... ;)

 

GD

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To be fair to my current mechanic in all this, who is a stand-up smart guy that I completely trust, he had no idea that a previous mechanic years ago fiddled with that screw. Since around here everyone knows these cars and presumably stays away from that screw, he had no reason to suspect it. And he was happy to try the solution and didn't charge me, as he has done in the past for the coolant hose shenanigan.

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Sure - but a google search would have brought up any number of forums just like this and within a matter of hours he would have all the same reply's you have had..... he didn't have to call out the throttle body. He could have done some homework before he told you to buy some expensive parts. The first thing you do is a search of this forum and others - if no one is replacing throttle body's then the chances of that being bad are slim. Further investigation would have yeilded the answer is what I'm saying and all the tools and experience in the world will not trump that. There is always going to be a problem that you haven't dealt with before and that's where the phone and the keyboard come into play.

 

GD

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No doubt, and a fair point. I guess the elite mechanics would do all of that, but it's not unreasonable that some of that searching burden is on the customer in this day and age. Fortunately this board exists, is monitored by sharp and helpful folks on a regular basis, and I know about it!

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Fortunately this board exists, is monitored by sharp and helpful folks on a regular basis, and I know about it!

 

Ain't it the truth--and aren't we fortunate!

 

GD makes an excellent point. Everything we need to know is out there, it just takes a little dedicated effort to search it out.

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  • 3 years later...
  • 2 weeks later...

thanks very much for the advice. had the sticky throttle thing happening on my 02 legacy wagon and have done as you advised, so far seems to be fixed, will watch closely over the next few days. thanks once again

ferg

well sadly the sticking throttle prob has returned! ant more suggestions before i bite the bullet and take it into the shop?

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