Partial shift into overdrive (A340F)?

[brosama]

Yes, I've searched but previous threads didn't really mention my exact symptoms. The tranny in my 2000 3.4L 4WD 134K miles, has an issue shifting into overdrive and grabbing gear after decelerating. The best way I can describe it is a partial shift.

- depending on acceleration, from 3rd to OD it'll shift around 3000 RPM
- the RPMs will drop and hold around 25OO for a few seconds (no notice in speed drop or increase)
- finally, the RPMs will drop to 2000 like it fully shifts
- I can't really reproduce the problem when manually shifting into OD via the button
- tranny and motor are at normal operating temperature
- tranny fluid is at correct level and doesn't look in too bad of shape, doesn't smell burnt
- no CEL

Other issue:
- slipping when decelerating and then accelerating
- ex: going around a residential corner in 2nd gear, when I hit the gas again it'll rev a little bit (a couple hundred RPM) before grabbing and dropping the RPMs
- doesn't always happen, kind of depends on my speed as I accelerate out of the corner
- not terrible feeling, but certainly not as smooth as I'd expect

I plan on dropping the pan and doing the DIY flush over my break so I'd like to also troubleshoot/fix this issue (if possible) around the same time. I'm also aware of the possibility that a new tranny may be on the horizon, but I'd like to prolong that day as much as possible.

I'm pretty clueless when it comes to internals of an auto, so any help is much appreciated! :biggrin1:

 

[kernel.panik]

Your first issue sounds like the torque converter locking up. If you give it a little gas when it drops to 2000k, it should unlock and bring the RPMs back up. I believe this is normal.

I have a 2002, and I am not familiar with the 2000 and what it came equipped with, but if you have an ECT button, try turning that on and see if shifting is more to your liking. It sets the shift points a little higher, especially if you are harder on the pedal.

 

[jasonoflivingston]

First off, I am no expert so take my thoughts with a grain of salt, but it sounds like the normal operation of a torque converter. If you were seeing a several thousand rpm jump before feeling things engage and lock up, I would be concerned that your vehicle is not downshifting properly, but a couple of hundred rpms doesn't seem abnormal to me. Is there a lurch when the transmission does engage coming out of the corners?

Typically, any solid application of the go pedal will unlock the torque converter whether that is accelerating out of a corner or ramping up to get into overdrive. Once the load settles down though, it will lock up and the rpms will drop.

 

[brosama]

Your first issue sounds like the torque converter locking up. If you give it a little gas when it drops to 2000k, it should unlock and bring the RPMs back up. I believe this is normal.

I have a 2002, and I am not familiar with the 2000 and what it came equipped with, but if you have an ECT button, try turning that on and see if shifting is more to your liking. It sets the shift points a little higher, especially if you are harder on the pedal.

It feels like 2000 RPM is where it should've shifted to because that's where it eventually lands and it feels normal. The stall/partial shift at 2500 is what feels abnormal. When I use the O/D button to shift it'll go directly to 2000 RPM and not hang at 2500 for a few seconds.

(These RPMs are examples, so they're not exact)

I have the ECT button so I'll see if that changes the behavior, although I'd still like to find out what's amiss if I can.

Thanks for the help!

 

[brosama]

First off, I am no expert so take my thoughts with a grain of salt, but it sounds like the normal operation of a torque converter. If you were seeing a several thousand rpm jump before feeling things engage and lock up, I would be concerned that your vehicle is not downshifting properly, but a couple of hundred rpms doesn't seem abnormal to me. Is there a lurch when the transmission does engage coming out of the corners?

Typically, any solid application of the go pedal will unlock the torque converter whether that is accelerating out of a corner or ramping up to get into overdrive. Once the load settles down though, it will lock up and the rpms will drop.

Yes, there is a lurch when it engages. The lurch isn't terrible, but it's noticeable. I'll look into the torque converter aspect a little more as that's what [MENTION=84359]kernel.panik[/MENTION] mentioned.

Thanks!

 

[kernel.panik]

It feels like 2000 RPM is where it should've shifted to because that's where it eventually lands and it feels normal. The stall/partial shift at 2500 is what feels abnormal. When I use the O/D button to shift it'll go directly to 2000 RPM and not hang at 2500 for a few seconds.

(These RPMs are examples, so they're not exact)

I have the ECT button so I'll see if that changes the behavior, although I'd still like to find out what's amiss if I can.

Thanks for the help!

That's what mine does, and it's a fairly new (toyota replacement) transmission. It almost acts like another gear when getting on the freeway, but it's just a normal shift, then settles when the torque converter locks up.

I could be wrong, but it sounds normal to me.

 

[brosama]

That's what mine does, and it's a fairly new (toyota replacement) transmission. It almost acts like another gear when getting on the freeway, but it's just a normal shift, then settles when the torque converter locks up.

I could be wrong, but it sounds normal to me.

Oh wow. If that's the case you just saved me a lot of worry! FWIW, the tranny feels pretty normal and solid outside of these two cases.

Anyway we can confirm if that's normal? Do other folks get the 4 1/2 gear feeling when getting up to speed?

 

[UTEP]

Yea…mine is similar..

Perhaps you like me have not driven an automatic trans in a long time and are not used to it. I was sure mine was in trouble after driving it for a week but now have come to terms that that's just how it goes. Makes me miss a 5-speed that I could gauge exactly what was going on.

From what I gathered from real good Toyota mechanics, 30+ variety, a Toyota automatic transmission is a tank and rarely self destruct IF maintained and not abused. Aside from milkshakes that is..

Also make sure your down shift cable on the throttle body is taught, not slack; not super tight-just remove the slack.

Do that flush, most here tend to run Valvoline MaxLife and I'm doing so as well, and make sure you either have a new radiator or bypass with remote cooler.

And then go have fun!

UtEP

 

[rideexileex]

Hmmm, maybe I'm not following just correctly, but maybe this will help. Sounds like the opposite mentality of 3rd->4th than 4th-3rd, but perhaps the thought process will match:

Scenario - driving up a hill/large load. If I'm on the gas, but not necessarily accelerating up a hill, while in D but still in 3rd gear, the RPM's will be slightly higher, as if the transmission wants to shift eventually into 4th. If I press the OD off button, the torque converter locks and the RPM's slightly drop, but the transmission and overall power feel more "planted".

Your first symptoms don't sound too crazy to me, like other have said, but can you elaborate on these?

Other issue:
- slipping when decelerating and then accelerating
- ex: going around a residential corner in 2nd gear, when I hit the gas again it'll rev a little bit (a couple hundred RPM) before grabbing and dropping the RPMs
- doesn't always happen, kind of depends on my speed as I accelerate out of the corner
- not terrible feeling, but certainly not as smooth as I'd expect

Can you define slipping? Slipping or RPM bounce is not a good sign...

 

[kernel.panik]

Oh wow. If that's the case you just saved me a lot of worry! FWIW, the tranny feels pretty normal and solid outside of these two cases.

Anyway we can confirm if that's normal? Do other folks get the 4 1/2 gear feeling when getting up to speed?

If you watch Addicted's video in this link, it does exactly what you are describing. He is already cruising in OD, and gives it some gas and the TC unlocks and the temps start rising.


http://www.toyota-4runner.org/3rd-g...r-how-fast-your-auto-tranny-can-overheat.html

I think your trans is OK, but it's always good to do a drain and refill. Just don't take it in for a flush! If you flush old fluid, old varnish being loosened can basically ruin an otherwise good tranny. If you do several drain and refills over some time, you'll be good to go!

 

[brosama]

If you watch Addicted's video in this link, it does exactly what you are describing. He is already cruising in OD, and gives it some gas and the TC unlocks and the temps start rising.


http://www.toyota-4runner.org/3rd-g...r-how-fast-your-auto-tranny-can-overheat.html

I think your trans is OK, but it's always good to do a drain and refill. Just don't take it in for a flush! If you flush old fluid, old varnish being loosened can basically ruin an otherwise good tranny. If you do several drain and refills over some time, you'll be good to go!

Thanks for the video. It's starting to make more sense now. So it sounds like:

Accelerating to 3000 RPM -> 3rd gear
RPM drop to 2500 RPM -> shift to 4th (feels like a shift)
RPM drop to 2000 RPM -> TC locked up

Is that right?

I plan on "flushing" in my garage following Dropping Pan And Flushing Transmission

 

[brosama]

Hmmm, maybe I'm not following just correctly, but maybe this will help. Sounds like the opposite mentality of 3rd->4th than 4th-3rd, but perhaps the thought process will match:

Scenario - driving up a hill/large load. If I'm on the gas, but not necessarily accelerating up a hill, while in D but still in 3rd gear, the RPM's will be slightly higher, as if the transmission wants to shift eventually into 4th. If I press the OD off button, the torque converter locks and the RPM's slightly drop, but the transmission and overall power feel more "planted".

Your first symptoms don't sound too crazy to me, like other have said, but can you elaborate on these?



Can you define slipping? Slipping or RPM bounce is not a good sign...

As I lightly accelerate out of the corner, I'll get an increase in RPM (say a few hundred) and then a shift/lock-up and the RPMs drop to normal (or what seems normal for a slow speed).

Is this the TC locking up again while in 2nd gear?

Sorry, kinda hard to describe completely, I can grab a video if that'll be better than a newb describing it...

 

[kbach]

That sounds exactly like my 2000 Tundra only described better than I have ever been able to. I've been starting to wonder if I have a 4 1/2 or 5 speed transmission sometimes. Both situations you mention sound familier to me but I don't think it feels normal at all. I hope you get some helpful sugestions.