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Old 03-24-2018, 04:50 PM   #1
Fireproof13
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Join Date: May 2012
Default 2009 Forester Issues

Our forester is having some serious trouble, it's something electrical and after speaking with multiple people at the Subaru dealership I have gotten nowhere.

I can't figure out why the throttle body is doing this. Every other time you start the car it will do this:


If you turn the key back off and on, it will start right up no codes. The next time you start it it will not make this sound, start right up and throw a crankshaft position sensor code. P0336.

I tried replacing the throttle body with no change. The only thing I can think of now is the ecu, please tell my why it isn't. We pulled the ecu and checked it over and there is nothing visibly wrong with it.
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Old 03-26-2018, 09:00 PM   #2
HudsonBrown1
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Im assuming that it is an etb (Electronic Throttle Body) if so it sounds like the motor is gone bad and its just going haywire, I would just replace the entire assembly you can probably get a used one off eBay fairly cheap.
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Old 03-27-2018, 09:09 AM   #3
Fireproof13
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Unfortunately that is the replacement throttle body doing the exact same thing.

We finally decided to let the dealership take a look at it and it seems that we may have found the problem. The crankshaft pos sensor should sense 30 teeth on the crankshaft sprocket and it is only sensing 29. We don't know why it isn't sensing one of the teeth, but I ordered a new sprocket and I'm gonna start with that. The mechanic explained to me that all of our symptoms make sense for this issue, so it seems that we at least have a lead on the problem. I'll update when it's fixed.

I was a bit skeptical that the sound that the throttle body is making could be related to a crank pos sensor issue, but the mechanic assured me that it is part of a self diagnostic that the computer runs through after clearing a crankshaft related code.
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Old 03-30-2018, 02:27 AM   #4
CosmoTheCat
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The ECU runs a throttle body sweep after you shut the key off. When you clear the memory, you erase the learned stops and it has to redo the sweep before it will allow the engine to start.
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Old 04-06-2018, 04:20 PM   #5
Fireproof13
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The issue has finally been resolved! Turns out that the crankshaft sprocket had a broken tooth. I put on a new sprocket and it's good to go!
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Old 04-06-2018, 05:07 PM   #6
Charlie-III
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1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

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Quote:
Originally Posted by Fireproof13 View Post
The issue has finally been resolved! Turns out that the crankshaft sprocket had a broken tooth. I put on a new sprocket and it's good to go!
Thanks for closing this out.
Glad it's fixed.

How the FRIG did a tooth get broken off?
Was a timing belt done recently?
Was this vehicle in a front end collision at some point?
Do you have steel eating rodents by your house?
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Old 04-07-2018, 01:18 PM   #7
wtdash
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Quote:
Originally Posted by Charlie-III View Post
Thanks for closing this out.
Glad it's fixed.

How the FRIG did a tooth get broken off?
Was a timing belt done recently?
Was this vehicle in a front end collision at some point?
Do you have steel eating rodents by your house?
+1000
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Old 04-07-2018, 02:28 PM   #8
IanT-EJ22
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Thats crazy. I don't have alot of experience owning cars with ETBs but it does make sense that the ecu would have some self diagnostics and fail-safes built in.
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Old 04-07-2018, 03:17 PM   #9
Charlie-III
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Quote:
Originally Posted by IanT-EJ22 View Post
Thats crazy. I don't have alot of experience owning cars with ETBs but it does make sense that the ecu would have some self diagnostics and fail-safes built in.
I believe the OP was talking about one of the timing fingers on the crank gear.
I will guess you're talking about an actual "tooth" that drives the timing belt? If I read you correctly, then the cam timing would be off and there would be bigger issues than what was stated.
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Old 04-16-2018, 02:18 PM   #10
Fireproof13
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Quote:
Originally Posted by Charlie-III View Post
Thanks for closing this out.
Glad it's fixed.

How the FRIG did a tooth get broken off?
Was a timing belt done recently?
Was this vehicle in a front end collision at some point?
Do you have steel eating rodents by your house?
It happened at some point during the rebuild we did. The rebuild went seemingly well, but then we started having these issues when it was done. My dad guesses that he must have either dropped it or bumped it with something since he did that part. Those teeth are pretty small and appear to be fairly brittle so even a dropped socket could probably break one.
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