TCU Reset?

I’ve had my 3.6R for about a month now and am becoming more acquainted with it. I noticed that the transmission doing some things I might characterize as a bit odd. For instance, it was a little rough downshifting as you slowed down, especially into first as you almost stopped. Also, I noticed that when you’re accelerating on light throttle, it sometimes will shift from second to third and then seem like it thought better of it and shift back down to second. I seem to notice that a bit more when I’m climbing the hill turning right from leaving work or when I’m turning onto the highway I used by my house. The highway but I can characterize most easily. It’s a four lane divided rural highway with a light. I stop at the light to turn left. When the light turns, I’ll accelerate across the first two lanes to maybe 20mph with fairly light throttle. As I begin to turn, I’ll reduce throttle a little. Usually as I’m completing the turn, it’ll have shifted into third. I’ll toe in a little more throttle — not much since you don’t need much with the big motor! — as it’s shifting and the tach will roll up quite a bit more than if it had stayed in third. There’s no lurch or anything; it does it pretty smoothly. Frankly, I might not think anything of it if I wasn’t actively paying attention to it. It doesn’t feel like it had locked the torque converter in 2nd and then unlocked it when I added the throttle. Plus, I think it shifts three times as I get to cruising speed. I’m not sure. I should probably shoot a video and post it here. I can say that it behaves exactly as I’d expect it if I put it in manual mode and use the flappy paddles. I’m inclined to think that mechanically it’s okay.

Figuring it could use new fluid owing to the fact that the PO wasn’t sure if it had been changed, I sucked about 4.5L of ATF out through the dipstick tube using a vacuum pump thing I recently picked up (you gotta get you one of these things!). The fluid was brownish, but didn’t have metal particles or smell burnt. Put the same amount of fresh Idemitsu Type HP in. The rough downshifts are gone now and it seems altogether happier. Though, it’s still doing the weird shifting thing.

Maybe this is normal behavior? I found a thread someplace (maybe here?) that mentioned something like that. I can’t find it again, though the guy said he changed the fluid and took it to Subaru to have them clear the TCU and do a learning procedure on it. Says it fixed it right up.

What do you guys think? I’ve gotta take it in in a couple weeks to have an airbag recall done, so I though I might see if they could do the TCU reset and adaptation on it while they had it. Don’t see any reason to spend the money on the hour of labor they’d probably charge me for it if nobody thinks it’d help. I do plan to suck out more fluid and replace it again when I get a free hour owing to the fact that I bought a case of ATF and might as well get as much fresh stuff in there as I can.

I may be way out there, but our civic does the same hunting gears when the MAF sensor needs cleaned...give that a shot and unplug the negative cable from the battery for 30 min or so to reset the ECU and see if that helps anything. It's an easy one to check out at the very least

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It runs fine and gets reasonable (for it) gas mileage, but it couldn’t hurt. It’s likely never been cleaned.

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The 5eat on stock mapping does have some quirkiness to it. And the fluid is generally an amber color for whatever reason. It wouldn't hurt to do the MAF cleaning, and maybe taking it in for a transmission relearn would likely help as well at least until the parameters set again. A lot of tribeca owners took to driving in sport mode all the time, but I don't recall if that is an option on the Legacy.

My Legacy doesn’t have any Sport settings. Just P, R, N, D, and M with flappy-paddles on the wheel. It’s entirely possible what I’m experiencing is normal. It doesn’t have any shift shock, slip or anything. Frankly, if I didn’t look at the tachometer, I may not think anything odd was going on. It might be that this transmission just tries really hard to do something other than what I think it’s doing. As for the fluid color, this 5EAT definitely uses red fluid. At least the stock Subaru ATF HP or Idemitsu ATF Type HP is red. The older ones used Dexron III spec fluid too, which was red too. Maybe you’re thinking of the gear oil in the front differential? That’s definitely a dark amber and stinks to high heaven owing to the sulphur content.

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i always disconnect the battery when i change the fluid in my wife's car. if not it will act funny for a bit before re-learing how to shift

The behavior I described didn’t change when I changed the fluid besides the shifts themselves becoming smoother and my no longer getting shocks on downshifts coming to a stop. I plan to change the fluid again since I only got about 4.5L out and have around 7L left still. Couldn’t hurt, right?

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To be clear, what Ed would have is an ECU tune that changes line pressure via the requested tourque values in the tune. Nobody has yet reverse engineered the TCU to be able to make any meaningful adjustments.

Basically Ed would be doing this:

https://legacygt.com/forums/showthread.php/tune-5eat-line-pressure-149282.html

http://forum.liberty.asn.au/viewtopic.php?f=56&t=21405

My Legacy doesn’t have any Sport settings. Just P, R, N, D, and M with flappy-paddles on the wheel. It’s entirely possible what I’m experiencing is normal. It doesn’t have any shift shock, slip or anything. Frankly, if I didn’t look at the tachometer, I may not think anything odd was going on. It might be that this transmission just tries really hard to do something other than what I think it’s doing. As for the fluid color, this 5EAT definitely uses red fluid. At least the stock Subaru ATF HP or Idemitsu ATF Type HP is red. The older ones used Dexron III spec fluid too, which was red too. Maybe you’re thinking of the gear oil in the front differential? That’s definitely a dark amber and stinks to high heaven owing to the sulphur content.

 

 

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Its red in the bottle but after a few miles it goes to the amber color. I used Subaru atf-HP as well as Amsoil signature series, they both turned amber after a month or so. The transmission shifted the same as it always did and still does with 173k miles on it. It is living the retired life with my mom so that will help with longevity for sure, but we never had any real issues out of it.

I changed the ATF the other day again and the car’s at the dealer getting an airbag recall done. I’m having them do the TCU memory 2 reset and relearn to see if that helps. I’ll let you guys know how it went.

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Just got the car back. Seems the same. Given that I was going to pay for an hour of labor no matter what, they also did the whole battery of diagnostics on the transmission. They checked for codes (none), ran the stall test (passed), ran the time lag tests (passed), hooked up the gauge and ran the line pressure tests (normal), and ran the road tests to check shift timing and quality (nothing out of the ordinary noted). It’s nice to know that my transmission is healthy. Seems the problem is that I’ve got the wrong expectations of it. I guess I’ve gotta change those expectations. It does fit pretty well with what people seem to say about the 5EAT, what with it being more of a leisurely transmission interested primarily in fuel economy and smoothness than responsiveness and sportiness.

That said, it sounds like I might want to look seriously at an XRT tune. What I’m reading and the videos I’ve watched make it seem like I might want one for the difference in transmission behavior I’ll get. Some extra horsepower, fuel economy, and drivability improvements would all be bonuses. I kind of want to get an axleback and an intake (the Nameless and the Takeda looked like all that’s really out there without going custom). I should probably wait until after I get those before engaging XRT so I only need to do the tune once.

Though, I did hear tell of XRT just doing something that amounts to a transmission tune for something like $175, even though he doesn’t actually tune the TCU. Anybody know anything about that?

I probably should just email him. :-p

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I'd email him, his prices fluctuate sometimes and he's always adding new methods to his skills.

I would suggest if you plan on doing an engine tune eventually, wait and do them at the same time. That'll probably save you some $$.

Hey, so I’m still thinking I might want to do a TCU reset and see maybe if I can straighten out the transmission a little.

I do have a better bead on what it’s doing. It’s always shifting, it just seems that the timing is kind of odd (to me). When I thought it was upshifting then quickly downshifting in the middle of it, it turns out I was toeing in more throttle as it was shifting into third. I don’t know if the engine is kind of peaky or what, but it seems like there’s a transition where you put in say 15% throttle to accelerate gently and you get about maybe 1800RPM before a shift, and when you put in a bit more throttle. It rolls up to like 2500RPM (but fairly slowly?). If I make that throttle position change as it’s shifting from 2-3, and it started the shift when I was at the lower setting, it’ll kind of lurch a little and the tach will swing way up.

It’s like there’s a granny mode and a normal mode and it has trouble switching from one to the other. Since I regularly make a left onto a divided highway and want to accelerate more as I complete the turn, I seem to regularly catch it as it does the 2-3 shift. It’s magnified by the fact that this transmission is so god-awful slow to shift, especially 2-3. If I accelerate outside of “granny mode,” it seems fine.

I also think this is why that TCU “tune” helps. Since he’s cranking up the requested torque values in that table, the car’s much less apt to be in granny mode.

Anyhoo, this brings me to a question. Once I find my long lost VAGCOM cable, I plan to use FreeSSM to clear

Memory 2. The few posts I find about that say “clear it and then drive around in different situations for about 60 miles to relearn it.” They’re all for the pre-2010 mode, though. There’s also some procedure involving certain throttle positions and shifting that’s a bit unclear.

The FSM doesn’t talk about doing that. They have you clear the memory and lift the car, then instruct it to do some repeat procedure. They say it will “vibrate.”

Who’s right here? Why should I be doing?

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I also have a '13 3.6 5EAT and an '07 LGT 5EAT. Turbo + 5EAT is more clunky than 3.6 + 5EAT. Not to say I don't have my fair share of quirks with the 3.6. My wife and I typically drive it in "manual" mode with stability control off and I drive the car hard. I'll get a odd shift in auto mode from 2nd to 1st on occasion.

I can get that thing hauling with a smooth push to WOT and manual shifting, much more so than just leaving in auto and mashing the gas.

I also have a '13 3.6 5EAT and an '07 LGT 5EAT. Turbo + 5EAT is more clunky than 3.6 + 5EAT. Not to say I don't have my fair share of quirks with the 3.6. My wife and I typically drive it in "manual" mode with stability control off and I drive the car hard. I'll get a odd shift in auto mode from 2nd to 1st on occasion.

 

I can get that thing hauling with a smooth push to WOT and manual shifting, much more so than just leaving in auto and mashing the gas.

Mine works fine, albeit slowly, in manual mode as well. It’s more this “mode transition” thing it does. And the “oh, you’re at 15% throttle in second and we’re at 2000RPM? Okay. Time to shift into thiiiiiird...wait you gave it a tiny bit more throttle lurch 2500 in third!”

I had thought it was bailing out on the shift for a while until I popped it into M for a split second to peek at the gear indicator when it did it. Plus, if I’m in M and in a higher gear but not accelerating much, it’ll be at lower revs with the converter obviously unlocked, and then you toe in a tiny bit more throttle and get a ton more revs than you’d expect. Plus, it rolls up slower than you’d think.

I’m not explaining this in a way that makes sense either. I should shoot a video.

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5EAT's ruin these cars in my opinion. I like my 2009 LGT but would love it if were a manual. I have performed the reset through FreeSSM numerous times, shifts improve for a while and then ends up back at the slide/bang 2-3 shift. The issue always surrounds that 2-3 shift. This is a car with 60k miles and new Subaru HP fluid. What gives...oh it's likely that failing turbine speed sensor that requires valve body removal. Nah, the reset is too easy, for now anyways.

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5EAT's ruin these cars in my opinion. I like my 2009 LGT but would love it if were a manual. I have performed the reset through FreeSSM numerous times, shifts improve for a while and then ends up back at the slide/bang 2-3 shift. The issue always surrounds that 2-3 shift. This is a car with 60k miles and new Subaru HP fluid. What gives...oh it's likely that failing turbine speed sensor that requires valve body removal. Nah, the reset is too easy, for now anyways.

 

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I’m still not clear on the actual procedure for ‘10-‘14’s. The manual says to clear memory two and then do a relearn while the car is off the ground. The pre-‘10 forum posts say you should clear memory 2 and then follow a procedure involving particular throttle angles and maybe shifting at certain RPM’s. Other people just reset it and drive it.

Which is it?

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Nobody knows off the top of their head?

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Have you had it tuned? Everything I have seen/read suggests there is a lot of improvement to be had.

 

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I still feel that there is a failure occuring somewhere in the transmission and that turbine speed sensor makes sense with the shifts that happen at odd times under the same throttle. It seems to do what it wants when it wants to, not what you tell it to do with throttle input.

As far as the reset goes on my 2009, I clear memory 2 and drive the car normally. I do go into manual mode and do some upshifts and downshifts. That process has lasted a few weeks or a few months. No rhyme or reason to it. This likely didn't help you guys but input is what keeps these forums alive. Best of luck with the cars.

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My car is running the OTS stage 1 (93 octane) tune from Cobb through the AP. I agree with you 100% that a custom tune would help but the car is box stock with the exception of an axle back exhaust so I'm not into it far enough at this point. When and if I go with an upgraded turbo and full exhaust, the car will be tuned. It's a driver for now.

 

I still feel that there is a failure occuring somewhere in the transmission and that turbine speed sensor makes sense with the shifts that happen at odd times under the same throttle. It seems to do what it wants when it wants to, not what you tell it to do with throttle input.

 

As far as the reset goes on my 2009, I clear memory 2 and drive the car normally. I do go into manual mode and do some upshifts and downshifts. That process has lasted a few weeks or a few months. No rhyme or reason to it. This likely didn't help you guys but input is what keeps these forums alive. Best of luck with the cars.

 

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It kind of sounds like I should just reset it and then go for a long ride. I live in the country within a couple miles of a highway, so I should be able to do some granny stuff out the gate to baseline it. Then I can play with the shifters some and then get on the highway and flog it.

I’m just bothered by the fact that the manual specifically calls out a procedure that nobody seems to do.

I’d like to see about getting it tuned, but it looks like that’ll probably cost about $700 by the time I get done. $170 cable, cost of the tune, back and forth with Ed and all. I don’t really want to tune the engine right now either. I already burn enough gas and having to switch to 93 would blow a bigger hole in my budget.

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