[MP81]

So, for roughly a month or so (according to my wife), the car's transmission has been "laggy", as she put it. Now, at first, I just chalked this up to the typical CTD lag we experience off the line. I have driven the car numerous times in the past month and noticed nothing out of the ordinary.

Well, going to meet some friends of ours, with her driving, I got to see exactly what she's been talking about. On a small incline, when my wife went to start moving, the car rolled back an alarming amount - and then absolutely SLAMMED into gear when it decided we should actually go forward. This happened multiple times. On flat sections, obviously no rolling behavior was present, but it still about gave us whiplash. From her description, she was giving it more and more throttle because it wasn't going anywhere, which makes sense why it was such a violent event. I asked her to be very light on the throttle and it still made a huge jerk, albeit not as large of an impulse as before when she gave it more throttle.

Then the last half of the drive it was fine. It was fine when I drove it home later that evening. It was fine when we took it to the store and back yesterday evening.

We're running AMSOIL Synthetic Trans Fluid, and I installed new cooler lines back in March, as the old ones were leaking (because of course they do). I've yet to check underneath the car, but I would really hope they hadn't started leaking after only a few thousand miles.

No codes or anything related, but something is definitely amiss.

 

[MP81]

Unless it's leaking again, fluid should be good. Then again, it's not an easy one to check, given the weird-as-**** refill procedure that ends with you counting the number of drips per second, then adding a set amount of fluid past that. I should be able to see a leak fairly easy on the aeroshield, though. If that's the case, I'm going to be rather upset - those lines are absolutely terrible to do.

Unplugging the battery isn't a bad idea. I need a reason to install your old CAI anyway, so this would give me the battery disconnect you suggested for that, as well.

This Aisin trans has got to be one of my least favorite transmissions I've ever encountered.

 

[MP81]

Odometer reading?

Miles since the last fluid change?

81,827 miles when I put 2.5 gallons of DEF in yesterday. 73,759 is when the trans lines went in, 3/27/18,.

Seems like a couple people have had their CTD transmissions replaced for exactly the same behavior.

Yeah...it did sound quite familiar...

Sounds like a transmission replacement is in order. My first reaction is do you have the correct fluid amount in the transmission? It’s almost impossible to really know.

Assuming it hasn't leaked any out - it should yes. I followed the funky Aisin AF40-6 refill procedure after I did the trans cooler lines. Wait for drips to be ~1 per second, reinstall check plug (which, oddly enough, is on the bottom of the engine - inside of the larger drain plug), turn engine off. Add X amount of trans fluid. Reinstall fill plug.

Trans had been great - almost like it was new - up until a month or so ago when my wife started complaining about it, but I hadn't had the "good fortune" of experiencing the problem until yesterday.

The issue is that it doesn't always happen. Our luck would be we drop the car off, dealer finds nothing wrong, then we get it back, and it acts up. Repeat.

 

[MP81]

I guess it hasn't been terrible - a lot of the issues prior were due to the leaking trans lines I wasn't aware of until I did the initial fluid change to Amsoil in January. It's always been a bit clunky for my tastes, on occasion.

But yes, I'd like this all taken care of before the PT warranty is up...

 

[MP81]

Oh, I'm not fixing this at all by myself. This car is still under warranty, unlike half the other bullshit we've had to fix, they can fix this, for free.

And that's the thing...if it decides to act up. If it's not, it's perfectly normal, so they wouldn't be able to experience it.

 

[MP81]

Does it tend to happen for the first xx miles of the day, or is that just how it went this weekend?

Seems like it kind of just happens whenever it feels like - sometimes it'll do it a lot more, sometimes not at all. She said it doesn't do it on the freeway...but given you don't spend much time stopped, I would expect it wouldn't even have the chance to show up. It did not seem to do it the first 15-20 min or so of our drive on Saturday, then all of a sudden the car was rolling backwards instead of moving forwards, and then the big jolt. That's when my wife said "this is what I was talking about".

 

[MP81]

Hahaha, kill it with fire! Either fix it, or make it permanently exhibit a problem requiring a replacement, haha!

I'd need a HANS device, if I did that. Just what I'm guessing was a medium amount of throttle that my wife applied, it was nearly painful.

 

[MP81]

I used AmsOil in transmission and no issues. My better guess is the stupid method of trying to put the proper amount of transmission fluid in it since it doesn’t have a dipstick. When just doing a change you just put back in what you took out, if you have a transmission line leak, it’s a guessing game in my book. I seriously doubt I keep my CTD past the warranty.

That's why I went with the "real" fill procedure, since the lines leaked out who knows how much, and then who knows how much more during removal. The only real guessing game there is how much fluid to add before you check the fluid level.

 

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What’s the harm in adding another 1/2 quart or so just for s#its and grins?

An upset overfilled transmisison, haha.

 

[MP81]

It definitely seemed to be very happy, for months, when I filled it following the "proper" procedure.

So, either it leaked fluid out again, or something is physically just taking a ****. Based on the fact the couple failures seem to be similar to what we're experiencing, I'm thinking this likely has nothing to do with fluid - especially since it's so intermittent. When our fluid was low, you could basically count on it to be useless.

 

[MP81]

The stop-neutral feature on the Aisin 55-50SN was problematic for 99% of them. Often a huge jolt or slow engagement as they got up there in mileage.

Most that owned that transmission disabled it or had to replace solenoids.

Surprisingly, it doesn't seem to be an issue for the 6T GM transmissions, but there may be something about the Aisin boxes that still don't like it.

You could be onto something there. If that starts to go out, you're essentially neutral-slamming the transmission because you're giving it throttle, but it hasn't put itself into gear yet. That's good for it.

 

[MP81]

Good idea - I'll tell her that.

Now, whether or not she remembers to do it, that is a different story.

 

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Yeah, I'm not sure what the dealer would replace - whether it be the solenoid or the whole trans.

Putting it in manual mode makes the problem disappear entirely.

 

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@Snipesy, is there something in the computer logs that can be seen that points to this happening?

My wife said she had a particularly heavy "slam" yesterday, but given how inconsistently it happens, I'm not sure we'll ever be able to get the dealer to see it, as it will probably decide to act fine while it is there.

Shifting it into manual - and thus, disengaging the neutral-stop feature - seems to entirely solve the issue.

 

[MP81]

I'm sure it detects it but that's all proprietary Aisin stuff. Not even GM tools can detect it and frankly I don't even know where to begin with it.

So, basically, our best shot would be to take it to the dealer and kidnap a tech to ride with us as we demonstrate the issue, when the transmission is currently misbehaving.

It likes to do it more in stop and go traffic, but it doesn't seem to always correlate with temp. It will do it for a while, then stop doing it while in the same traffic. So just sounds like a solenoid (or whatever controls it - TCM?) going out. The sometimes it doesn't do it at all.

I have the 6T45 transmission in my 2012 diesel and it seems fine so far. I did notice that if I put the shift in manual mode the transmission doesn't go into neutral when the car is stopped, maybe it is worth trying to see if it makes a difference?

It solves the issue entirely, not going into neutral when stopped.

 

[MP81]

Ours hasn't done it at all since summer, and our PT warranty is done in May (wonder if I can get a GM extended PT warranty or anything before then).

The car has been at the dealer since Wednesday afternoon to replace the passenger halfshaft (ripped boot) and I haven't received even a call that it would take longer than the day I expected - maybe two if they had to order the axle, since I highly doubt they had a CTD axle on hand, but it should be a quick replacement, as it's just a halfshaft.

My buddy jokingly asked "what did they break?" - I truly hope they broke the transmission.

 

[MP81]

Bumping this back up, as the weather has every-so-slightly begun to remember it's not winter anymore.

And with it, means the transmission has become somewhat problematic again. Doesn't seem to be doing the neutral slam just yet, but it is making for some extremely violent downshifts. If I were to guess, on the 3-2, based on the speed my wife was going when I was in the car with her.

I still have the borescope from AutoZone that I rented to find the pintle cap that conveniently fell down into the intake port of my brother's 3100 which I had just replaced the gaskets on (was reassembling the vehicle at this point, so the lower intake was on, and I was not taking it back off), so I am going to utilize that to have a look underneath and see if the lines are leaking again or...hopefully...the case is leaking at the seams.

The latter would be most beneficial, as that means trans replacement - something that needs to happen soon, as PT warranty is up in about one month.

 

[MP81]

Traditional torque converter automatic.

Just crap programming.

Yeah, I've never been impressed with the AF40-6 in this car, but when we first got the car it was, if a little clunky. I've always been impressed with the calibration focusing on actually downshifting and engine braking without requiring you to slap it over to manual (unless you want more), but this 3-2 slam is new.

I took a peak underneath over the weekend and it doesn't seem like the lines are leaking (again, yet), but I would sure love to see some weeping at the case split - as that's pretty definitive of "replace it now".

 

[MP81]

I'm wondering...does anyone have the specific transmission fill procedure from the service manual for this car?

If I recall, the Chilton manual stated that after the check plug drips at a very-scientific rate of one drip per second, to close the check plug, turn off the vehicle, and add 0.4L of trans fluid.

However, "AutoMate" is what I have access to now, and it does not state anything about an additional 0.4L of fluid.

It has me curious - could all these issues be due to too much fluid. It was getting extremely bad sitting in a 15 minute traffic jam in 90 degree heat last Thursday, to the point where I had to leave it in manual mode so it wouldn't shift to neutral - one time I did that, it still slammed into gear after a second or two of me moving it over to manual mode.

It was also getting real jerky on the one downshift on Sunday, and that was right away on a cold start, when it was not nearly as hot out - so that's obviously not temperature dependent.

 

[MP81]

Bump! I feel like I remember seeing something somewhere, but cannot remember where.