5eat or Diff big bang scare, but now behaving?

[2010 5EAT Legacy GT]

Hi guys got the 5eat 5th Gen 2010 GT with a Ecutek tune.

 

About 4 months ago I was going around a corner in 2nd or 3rd and the trans felt like it was in neutral just after I had straightened up. I immediately came off the throttle (should have quickly pushed it into N) then suddenly massive bang from the rear of the car and back to normal. Thank god I was at 0% throttle.

 

Latter about a week or 2 latter, i felt something similar with pulsing moderately heavy judders/ bangs, again felt and sounded like it was coming from the rear of the car, again I completely went off the throttle.

 

Panicing for my life I immediately got atf changed, front diff oil. Changed and rear diff oil changed. Tuner noted metal shaving in the rear diff.

 

4/5 months have passed and have not had anything like it since. No codes, no CEL and have not been babying it. I can assume the tuner might have done a TCM reset as my map disk had forgot itself when I got the car back (at the very least the battery was disconnected).

 

Any thoughts? Have not done any of the 5th gen TCM updates (if they exist). Could my diff oil or atf have been so dirty / out of spec that undefined behaviour combined with my tune could have caused this behaviour?.

 

Let the 5eat wizards and speculators have at it!!

[dgoodhue]

It is normal to have metal shavings in the rear end from break in period. (mine had metal shaving at 20k miles) Metal chunks and metal shavings after that it is not normal. If it is has not made the bang since then, I wouldn't worry about it unless it happens again. You could have hit some in the road that made that noise.

[FLlegacy]

Also make sure both of your cv axles are fully seated in the rear diff. On another forum a member had one axle pop out of the diff at some point, so sometimes it would lose power.

 

Sent from my SM-G965U using Tapatalk

[dudemonster]

If that’s the case, tell your leggy that it’s only going to hurt for a second, then pull the wheel straight out as hard as you can and let it snap back into place.

 

This non-professional medical advice brought to you by the University of Scranton Rugby Club.

Edited May 12, 2020 by dudemonster
Typo

[2010 5EAT Legacy GT]

Update: Happend again. I think it is down to my Tune, Only happens in S, not S# or I. Must be some bad params in my S 5EAT tune.

[KiwiBR9]

Hey mate,

 

There's a pretty common fault in our 5EAT. The "Turbine speed sensor 2" is more than likely at fault. Mine completely shit itself and every shift between 1-2 was a slam shift and sometimes 2-3. If it starts to happen regularly it'll need replacing. If it happens when you're out and about, put it into tiptronic and take off in 2nd gear. This will help you limp home/somewhere safe.

 

The part is cheap as chips (under 100). Try find someone who will replace just the part not the whole valve body. Or do it yourself. It's not a huge job if you're comfortable with cars.

 

Anyway don't stress much for now.

[moral hazard]

I agree with KiwiBR9, my 2010 GT 5eat has the issue and eventually it did throw the turbine speed sensor error (which is a hall effect sensor).

 

I'll keep driving until it gets worse and attempt to change the sensor myself (sadly requires dropping the valve body ).

 

A common issue with the tribeca also, so be sure to check for that error code discussion on those sites as well if you want more detail.

[2010 5EAT Legacy GT]

Thanks for the Info. Weird I'm not getting any codes for it though? even thou its done it 3 times in total. I get it between 3-2 I think, on the Downshift it goes into limbo mode (Feels like neutral).

 

The Second time it felt like it was surge-bang ing . Multiple mini bang pulses.

 

Hard to tell but if it was Turbine speed sensor 2 it would 100% show up as a code? Or it it possible that the Transmission just has no idea when it happens.

 

Cheers again, I know the warning signs now so im confident if it ever happened again I could rapidly chunk it into neutral and save her .

Edited January 28, 2021 by 2010 5EAT Legacy GT

[moral hazard]

It took quite a while (months) before my bang shifts eventuated in seeing the error code and limp mode.

 

I simply clear the code and continue on at this stage.

[ThreeSixMafia]

My 3.6R is having the Turbine Speed Sensor 2 problems and it's the same symptoms you're having plus more.

 

Mine doesn't set a code until after I reach third to fourth and cruise past 40mph.

 

It's notorious for sliding into neutral on an incline, during heavy load, or after being driven a while at a constant speed.

 

Mine has a lag and hesitant shift from 1 to 2, then slips out of 2 as it's shifting into 3 and if I don't watch it, my revs will sky rocket to the redline and will slam back into gear.

 

I can prevent the code from surfacing if I "massage" the gear from 3-4 or 4-5 with the paddles and keep doing so. If I stay at a constant longer than a second past 40mph however, the code comes up.

 

Select lever position still in drive, but the cluster shows blank or a hyphen in place of a gear. From there it's either stuck in neutral in which case I can only fix that by pulling over and resetting the code so it re-engages drive gears or it's stuck in 4th(yes even with paddles, you can't shift) and that I can temporarily fix by resetting the code as I drive, but if that Hall Effect Sensor is still struggling, it will send the code again, until it clears the cluster back to "D", only then can I finally reset the code completely will it go back into normal driving conditions.

 

I will be replacing the Hall Effect Sensor within the next few weeks and hope these symptoms go away. I'll be making a thread with a step by step on how I'll dive into it.

 

I should mention, these codes did not immediately come up. It was small symptoms and it progressively got worse over time. Three months into ownership, it started throwing those codes. I would take a stab at that generic Hall Effect Sensor for $80-100 and have it around to do the install yourself in case it does get worse and you get codes within the next few months. If it turns out you don't need it, it will be an easy sell to anyone with a 5EAT, because apparently this is a common problem -_-

Edited January 29, 2021 by ThreeSixMafia

[2010 5EAT Legacy GT]

Thought I would update. 
This was eventually tracked down to the all too common 5eat Speed sensor 2 malfunction.

[Scubaboo]

Thank you for the update!

How did you fix it?  Replacement sensor or new valve body, or...?