[Timberwolf]

2008 Outback with 2.5, non-turbo, 114K mi, AT.

The issue seems to be that the car does not know when to shift down to 1st gear at stop signs. If I stop completely (like you're supposed to), and take off, it starts in 1st and I can accelerate at any pace I wish. If I do a rolling stop (like you do when you're in a hurry), slowing to 1-2 mph and then accelerate, it seems to stay in 2nd, and it's fine. If I'm in traffic at a stop light, and have to slow way down to a crawl, it doesn't matter if I never stop completely or if I do, it starts out in 1st and does fine too. However, if a make a quick stop (may stop for only a fraction of a second), and then go, it stays in second until I accelerate, then it drops to first, and shifts a bit hard doing it. No other shifting issues between any other gears either. I've heard there is a tranny reflash that can be done at the dealership for under $100. Is this the kind of issue that the reflash can address? I have done the battery disconnect reset trick, and that doesn't seem to have helped.

 

[CNY_Dave]

I was having this problem in my '05 forester, seemed to be caused by a failing throttle pedal position sensor (throttle by wire).

Was bad enough to set a high idle, bind the awd just a bit while coasting, but only rarely set a code.

 

[Subiez]

Timberwolf . . . I don't have an answer, but thanks for making me aware that this NOT normal. I have the same issue in my (new to me) '08 OB 2.5 AT. Mine does it when accelerating from a coast at around 10mph, most notably when turning a corner. I might give the TPS a try, seems like an easy start. I have not heard of the 'flash' you are talking about, but wondered if a proper transmission flush and fluid change would help?

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[Timberwolf]

Don't do a flush. Those flush machines are notorious for wreaking havoc on engines and transmissions alike. Alot of people do several partial changes to get most of the old fluid out, but I have been doing complete changes for years on all my vehicles as follows.

1. Find the output hose from the transmission that hooks into the radiator. On your car, this is the one on the passenger's side. I'm almost certain of this, but you may want to verify to be sure.
2. The pan holds about 4 qts, so put the hose in a bucket or empty container. I find that empty antifreeze bottles work great.
3. Have someone turn the car on while you monitor the level in the container. When 4 qts are pumped out, turn the car off.
4. Add 4 qts of new tranny fluid.
5. Repeat the pump out procedure again.
6. Add 4 more qts of tranny fluid.
7. Repeat the pump out procedure, but stop at about 2 qts this time. I'm pretty sure the system capacity is 10 qts.

If you want to make absolute sure you get 100% of the old fluid out, keep pumping until you see clean fluid coming out. I'm satisfied to stop at 10 qts.

This is my 3rd car with this transmission in it. Its the first 3rd gen, and the first I've had this issue with. I think they got too cute with the computer controls on this generation, and maybe the computer is a little too smart for the tranny. Anyway, I've read about a reflash, and while it says it does address hard shifting issues, I could not find anything in search that directly addressed the problem we're having. The full tranny fluid change did not solve my problem. I'm almost certain it is an electronic issue, not a physical one, so that didn't surprise me. It just doesn't know when its supposed to shift into 1st gear for some reason. I'm going to take it in to have the airbag recall done later this month. I may just have them do the reflash to see if it helps.

 

[Subiez]

Don't do a flush. Those flush machines are notorious for wreaking havoc on engines and transmissions alike. Alot of people do several partial changes to get most of the old fluid out, but I have been doing complete changes for years on all my vehicles as follows.

1. Find the output hose from the transmission that hooks into the radiator. On your car, this is the one on the passenger's side. I'm almost certain of this, but you may want to verify to be sure.
2. The pan holds about 4 qts, so put the hose in a bucket or empty container. I find that empty antifreeze bottles work great.
3. Have someone turn the car on while you monitor the level in the container. When 4 qts are pumped out, turn the car off.
4. Add 4 qts of new tranny fluid.
5. Repeat the pump out procedure again.
6. Add 4 more qts of tranny fluid.
7. Repeat the pump out procedure, but stop at about 2 qts this time. I'm pretty sure the system capacity is 10 qts.

If you want to make absolute sure you get 100% of the old fluid out, keep pumping until you see clean fluid coming out. I'm satisfied to stop at 10 qts.

This is my 3rd car with this transmission in it. Its the first 3rd gen, and the first I've had this issue with. I think they got too cute with the computer controls on this generation, and maybe the computer is a little too smart for the tranny. Anyway, I've read about a reflash, and while it says it does address hard shifting issues, I could not find anything in search that directly addressed the problem we're having. The full tranny fluid change did not solve my problem. I'm almost certain it is an electronic issue, not a physical one, so that didn't surprise me. It just doesn't know when its supposed to shift into 1st gear for some reason. I'm going to take it in to have the airbag recall done later this month. I may just have them do the reflash to see if it helps.

Without redirecting you original post too much . . . Is there a filter to change? What fluid does everyone recommend? Thank you!

Back to the reguarlly scheduled discussion . . . Any merit in the throttle pedal position sensor replacement? Looks they can be had for about $100 on rock auto.

Joe

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[subnz]

Don't do a flush. Those flush machines are notorious for wreaking havoc on engines and transmissions alike. Alot of people do several partial changes to get most of the old fluid out, but I have been doing complete changes for years on all my vehicles as follows.

1. Find the output hose from the transmission that hooks into the radiator. On your car, this is the one on the passenger's side. I'm almost certain of this, but you may want to verify to be sure.
2. The pan holds about 4 qts, so put the hose in a bucket or empty container. I find that empty antifreeze bottles work great.
3. Have someone turn the car on while you monitor the level in the container. When 4 qts are pumped out, turn the car off.
4. Add 4 qts of new tranny fluid.
5. Repeat the pump out procedure again.
6. Add 4 more qts of tranny fluid.
7. Repeat the pump out procedure, but stop at about 2 qts this time. I'm pretty sure the system capacity is 10 qts.

If you want to make absolute sure you get 100% of the old fluid out, keep pumping until you see clean fluid coming out. I'm satisfied to stop at 10 qts.

This is my 3rd car with this transmission in it. Its the first 3rd gen, and the first I've had this issue with. I think they got too cute with the computer controls on this generation, and maybe the computer is a little too smart for the tranny. Anyway, I've read about a reflash, and while it says it does address hard shifting issues, I could not find anything in search that directly addressed the problem we're having. The full tranny fluid change did not solve my problem. I'm almost certain it is an electronic issue, not a physical one, so that didn't surprise me. It just doesn't know when its supposed to shift into 1st gear for some reason. I'm going to take it in to have the airbag recall done later this month. I may just have them do the reflash to see if it helps.

Do it this way also on 3.0R 5EAT - and agree a much better way of changing fluid than 2 to 3 drain / top ups.

 

[Timberwolf]

Although I forgot to put it, you obviously need to re-attach the hose to the radiator, and top off the fluid.

As far as the filters, there are two. An internal filter in the pan, and a spin on. Subaru says not to replace filters, but I always replace the spin on. Your generation determines what type fluid you use. Gen I & II spec Dextron III, but I use IV. Gen III specs type HP, I used Idemitsu ATF Type HP.

I'm going to look into the throttle pedal position sensor. I guess maybe it could be that its calibrated wrong so that when I let off, it thinks it is still partially depressed, so it doesn't downshift, but I'm not sure about that. I found a reset procedure for that. I'm going to give it a shot when I find the time. I attached it if you want to give it a try. Its for an Impreza, so I'm not 100% sure it will work on our cars.

 

[Subiez]

Thank you! I will give the recalibration method a try tomorrow. Results will follow . . .

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[Subiez]

I did the recalibration method this morning with mixed results and emotions. It did not fix, but seems to have improved the issue.

Mine only does it during this scenerio (just fyi for others) . . . Driving normal speed ~35mph, normal braking when making a turn, speed reduced down to ~15mph, press accelerator, then hesitation before accelerating, then a very notable "KA THUNK" hard shift down to first, and finally normal acceleration.

The process I used . . .

1. Wait for car to cool down, preferably overnight.

2. Disconnect negative battery terminal, turn key on, turn headlights on, press brake pedal and hold for a few seconds.

3. Wait about 3 minutes.

4. Make sure everything is OFF, lights, blower, acc., etc. and doors shut.

5. Turn key all the way to ON, after you stop hearing relays clicking wait about 20 seconds and slowly press and depress the throttle pedal from no throttle to full throttle four (4) times.

6. Start the engine.

7. Wait about 10 min., or until temperature is up and fan has kicked on, AND the idle is stable at about 700 rpm.

8. Press the accelerator pedal slightly, about 2mm. My RPM actually dropped and fluctuated from 500 to 800 rpm . . . HMMM; not sure if that is bad or normal. I let it do this for about 5 seconds.

9. Depress the accelerator until idle is stable at 700 rpm.

10. Press accelerator pedal till rpm is about 1000 rpm, and let it the car stabilize. Again, mine really struggled at 1000 rpm. I held it there about 10 seconds.

11. Depress the accelerator until idle is stable at 700 rpm.

12. Press accelerator pedal till rpm is about 1300, hold until stable. Return to 700 rpm.

13. Press accelerator pedal till rpm is about 1500, hold until stable. Return to 700 rpm.

14. Press accelerator pedal till rpm is about 1800, hold until stable. Return to 700 rpm.

15. Press accelerator pedal till rpm is about 2000, hold until stable. Return to 700 rpm.

16. Press accelerator pedal till rpm is about 2500, hold until stable. Return to 700 rpm.

17. Press accelerator pedal till rpm is about 3000, hold until stable. Return to 700 rpm.

18. Press accelerator pedal till rpm is about 1000 rpm, after it is stable, increase to 1300 rpm, again to 1500, again to 1800, 2000, 2500, and 3000 rpm respectively. Do the same sequence in reverse.

19. I was troubled by the "stumble" I had at very partial throttle and at 1000 rpm. I tried to get it to smooth out, but it still struggled and varied quite a bit. Problem with TPS?

20. Drive the car normally for about 15 min.

21. Turn car off and wait approx. 15 to 20 min.

22. Drive car normally for about 15 min. And please post results if you do this same procedure for my sanity.

I was able to get the car to recreate the "KA THUNNK" once like normal, once less severe. Other shifts seemed normal, possibly improved, but could just be my imagination.

 

[Timberwolf]

One question, in step #3 I assume you are reconnecting the battery after the 3 minutes is up, correct?

 

[Subiez]

One question, in step #3 I assume you are reconnecting the battery after the 3 minutes is up, correct?

Good catch, you are correct.

I picked up a accelerator pedal from the junk yard over the weekend, but its from a 2006. I need to check, but I'm not sure they are interchangeable with my 2008.

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[sternman318]

Good info @Subiez and @Timberwolf. I'm going to flush my transmission soon, I like that method. I also have the weird transmission behavior when slowing for turn then accelerating. Weird hesitation followed by hard shift. I thought maybe my transmission was on its way out, but maybe it's not. Any updates, or is everything still the same?

 

[Subiez]

Everything is still the same after a transmission "flush" with 13 quarts (opps) through it and a new filter. I just got a feel for when it does it and have altered my driving habits to avoid it. If you figure it out let me know. Otherwise mine drives fine.

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[sternman318]

How do I reset/relearn the TCU? I read to do it following a transmission flush but can't for the life of me find it. Do I just disconnect the battery and kill residual power?

 

[sternman318]

Also, followed the flush procedure from before, highly recommend. SUPER easy and looks like it's a ~100% rather than dilution flush. Lifted car a few inches, removed the return line on the passenger side of the oil cooler, attached a short length of hose to the cooler, and drained until a milk jug. Pan went dry for a second so maybe be a little more conservative on draining exactly 4 qts, but should be fine.

 

[CNY_Dave]

How do I reset/relearn the TCU? I read to do it following a transmission flush but can't for the life of me find it. Do I just disconnect the battery and kill residual power?

Yes.

 

[DavidPeab]

Just disconnecting the battery will not reset the TCU completely. There are two options to do it with Free SSM. One will do the job and the other will screw up the trans. Not sure which is which.

Here's what I did when I had the exact same problem as you, but with the 5EAT rather than the 4 speed. I replaced the ATF with OEM Subaru HP fluid. Had the dealer reset the TCU for $80. Tens of thousands of miles later and no issues.

 

[sternman318]

Just disconnecting the battery will not reset the TCU completely. There are two options to do it with Free SSM. One will do the job and the other will screw up the trans. Not sure which is which.

Here's what I did when I had the exact same problem as you, but with the 5EAT rather than the 4 speed. I replaced the ATF with OEM Subaru HP fluid. Had the dealer reset the TCU for $80. Tens of thousands of miles later and no issues.

Good to know. I'll probably just leave, things seem to be fine, I've learned my lesson about fixing things that aren't broken haha.