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2008 Outback H6 3.0L L.L. Bean
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6 Posts
Discussion Starter · #1 ·
I have an 08 Outback H6, 180k miles, and just a few days ago the car started to act unlike id ever seen it before.

At first, it would drop out of 5th into 4th while on flat ground/stable throttle and then quickly shift back up. in the next few days the car went from that behavior to failing to time shifts properly across all gears, extreme shift shock in all gears UNTIL its heated up. With that said, the car starts at 70-80F (SoCal) elminating the tranny to be forcing extra heating by dropping down a gear i feel, nor has this happened before.

Whats odd about all this is, no codes what so ever, ATF is in good shape and also at proper levels.
When inspecting with Free SSM both the Engine computer and the Transmission computer have no stored or pending codes of any kind.

Where should I start looking? Am i facing a total mechanical failure of my trans? or could the Transmission computer be dieing, because no electronics are reporting any issues, but the car is failing at shifting a gear well until it warms.
 

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OBW H6 VDC, Tribeca, XT6
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12,385 Posts
good news - total mechanical/catastrophic failure is unlikely
bad news - sometimes these can be tricky to nail down

one key note will be: is it getting worse over time?

it's fairly common for an engine issue to feel like a transmission issue.
would you bet $1000 it's absolutely a transmission issue?

1. check your transmission pan and make sure it's not dented.
2. any recent accidents or car washed (engine bay/trans got wet)?
3. was it very humid when this happened or after a beach trip, off road?
4. have the engine or trans ever been out or seen major work?
5. has the ATF filter ever been changed? (this shouldn't really matter but just asking)
 

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2001 VDC Wagon - White pearl - 302,000 km
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466 Posts
Check the temperature of your fluid, as reported by the sensor in the trans. My 03 4EAT would do similar things. Albeit, it would commonly set the AT fluid temp light ablaze to tell me there was something wrong....as if my sore neck wasn't enough indication. Not sure if the 08 has the sensor, but an incorrect signal can make the ECM think the fluid is hotter than it is, causing the shift solenoids to shift too quickly, resulting in shift shock. In my case, I had an intermittent open circuit from the sensor to the ECM. It would jump out of overdrive on the highway too...scary the first couple times.
 

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18,858 Posts
ditto what idosubaru suggested.

Just to be sure, there's no codes indicated by FreeSSM, but are there any warning lights on or flashing?

In addition, are the shift etc., symptoms only until the transmission has had time to fully warm up, or are there ongoing issues well after? (Normal operating temperature is roughly between 150 and 180 F.)

ATF temperature is one of the parameters that determine torque converter lock-up and shift points. Might want to check what FreeSSM shows for the ATF temperature after the car has been parked, say, overnight, and the ignition is set to On, but the engine is not started. It should be close to the ambient temperature at your location. Then, after the car has been driven for some time, check if the ATF temperature is then close to the normal operating range.

I'm not sure how good FreeSSM is at retrieving transmission codes. Your 08 has a built-in code reader that perhaps could be used. It's described in the first post of http://www.subaruoutback.org/forums...9-how-read-diagnostic-trouble-codes-dtcs.html .
 

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2008 Outback H6 3.0L L.L. Bean
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6 Posts
Discussion Starter · #5 ·
good news - total mechanical/catastrophic failure is unlikely
bad news - sometimes these can be tricky to nail down

one key note will be: is it getting worse over time?

it's fairly common for an engine issue to feel like a transmission issue.
would you bet $1000 it's absolutely a transmission issue?

1. check your transmission pan and make sure it's not dented.
2. any recent accidents or car washed (engine bay/trans got wet)?
3. was it very humid when this happened or after a beach trip, off road?
4. have the engine or trans ever been out or seen major work?
5. has the ATF filter ever been changed? (this shouldn't really matter but just asking)


1. Tranny pan is fine
2. None
3. No.
4. Yes, 3 weeks prior i completed a engine rebuild replacing the head gaskets and water pump, all interior engine components looked great during rebuild. Additionally the Valve body was replaced 4 months ago.
5. No, should i weed out this as a cause?


To elaborate on the engine rebuild, after the rebuild the engine, the canister purge valve had a leak in the intake hose, in the process of fixing this, (as it was giving a P0442 TC) i wiped the ECU two times otherwise it would take weeks to guess at random spots. After fixing the leak, i reset the ECU one last time, and since then the car began to act funny. that "Acting funny" progressed into the transmission issues Ive had.

And to clarify there was NO codes on TCU/ECU and NO lights or indicators what so ever. Just the tranny slipping and searching.


Im going to wipe the TCU at the same time as the ECU and attempt to monitor temps as suggested.
 

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2006 Subaru Outback Wagon LLBean 3.0R Automatic
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1,034 Posts
3 weeks prior i completed a engine rebuild
hope you find the issue..
just a thought:

has the car had a chance to relearn its throttle settings on Premium fuel for at least 1 full tank? (just say NO to Regular Gas)

My LLBean H6 3.0 shifted like a DOG on Regular. Downright dangerous trying to merge or pass on the freeway..

I use premium now, and Sport mode.. when I say go, I mean NOW, not later.
 
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