Dealer says the solution to my stuttering at low rpm accel is a new tranny... Really? Need guidance

1993 (2WD), 2002 (Dbl Cab Off Road), 2016 (Dbl Cab Off Road) Tacoma owner... My Toyota loyalty is being tested...

I didn't think that I would need this level of assistance so soon in 3rd gen... Here's the background.

While back noticed an occasional stuttering of the engine - like if you started too high in a manual tranny car at low speed. Didn't think much of it. Then, recently I discovered what conditions created the stutter. Now, I can't avoid it.

-2017 3.5L A/T Offroad
-91k miles
-Out of warranty
-Not driven off road in any heavy fashion - tame desert roads
-Well maintained​

Stuttering occurs only with WARMED up engine, not cold. 1200-1800 rpm under slow acceleration. It's easily reproducible. And, if you hold it at the rpm without a shift, then you can set up a pretty good vibration that seems to resonant. Seems to happen at 3 to 4th gear. But, I have felt it at lower levels above 4th gear. However, with California roads, it's hard to tell if it's the engine or the crappy roads.

Took care of the low hanging fruit myself:

(1) new air filter,
(2) gas comes only from CostCo
(3) added Seafoam to clean up the fuel system
(4) cleaned the MFS
(5) cleaned the throttle body intake
(6) even replaced the CPS sensor
(7) bought a BlueDriver code reader (highly recommend)... no codes/errors that indicate anything wrong.
(8) No check engine lights, ever.
(9) Spark plugs were replaced back at 76k.​

So, figuring this was a devilish problem, scheduled an appointment at the local dealer. Took the technician on a drive to show him the issue. He easily reproduced it. Speed up.... End of the day, end up talking to the 2 service managers. They drop the bomb. It's your tranny!

Here's what they said:

(1) Tech tested torque converter (good)
(2) They reflashed the ECU (TSB, good)
(3) Individually actuated the solenoids (good)
(4) Tech said the 3rd and 4th gear packs (assuming he means the planetary gears clusters) have weak pressure. (BAD)
(5) Nothing we can do except new tranny... Give me a break, a new tranny at 91k in a fricken Tacoma! $10k from dealer.
(6) They also don't think a full flush will help, could make things worse.​

So here are my questions, thanks for spending you time getting to this point.

(1) Anyone else go through this and can share what you did?

(2) Anything else I should try?

(3) With this happening only with the WARMED engine, does this indicate another possibility to anyone. I was originally thinking fuel pump or something related to air/fuel ratio before the bomb dropped.

(4) I'm thinking, if it really is the tranny, then doing a fluid wash would be the last option. If it accelerates the issue, then so be it... new tranny. If it helps, wonderful!

(5) Anyone have experience with recovered trannys from low mileage crashed trucks from an auto dismantler (likely $2k) less than remanufactured from Remanns or a dealer.

(6) When replacing a tranny, should you replace the torque converter?

(7) Anyone go through a tranny replacement? Things to watch out for? Number of hours needed? Level of difficulty for a trained mechanic?​

Thank you for any guidance or wisdom that you can provide.

 

Did you have the fuel pump recall done? I believe 2017s were part of that recall. I would start there.

https://tfltruck.com/2020/10/toyota...-million-vehicles-includes-tacoma-and-tundra/

 

2017’s were not in the recall.

 

No recall for my fuel pump unfortunately... Mine is an early 2017 bought in February. But, it still doesn't mean that it shouldn't be part of the recall possibly. Will investigate what it entails. Thanks, TA2016.

 

Edited: I thought your title meant it was your new transmission doing it!

So, are you sure that there was not another issue causing the problem like a engine mount issue or something that could be causing it?

 

Even if your 2017 was not part of that recall, I would still look at the fuel pump before spending 10 grand on the transmission.

 

Yeah, you are right. I should have posted that they at least should check the fuel pump. Good call.

 

OnHartung'sRoad, I haven't replaced the tranny yet. It's still the one that came with the brand new truck. I'm trying to see if there options to replacing it... Or if the dealer is simply wrong in their prognosis.

 

Have you tried gas other than Costco or higher octane ? I made a post not too long ago, where my Tacoma seems to run like shit on Costco 87. It tends to cause stumbling under load at under 2500-3000rpms

 

Before you go down the new tranny rabbit hole with the dealer, I would get a second opinion from a reputable independent transmission shop. Even if they agree it needs to be replaced it would be good to get another quote. You're spending your money so you're not married to the dealer for a warranty repair on this one (unfortunately). You can take it wherever you want.

 

I thought your title meant it was your new transmission doing it!

TA2016’s suggestions about checking the fuel pump are good ones. Also have them check the engine mounts and other driveline support points…

 

I saw those posts about octane. I will give that a try since it's easy to do once the full tank empties. Could also try an octane booster, I would think. Thanks, maxmk8.

 

Here is some TW chatter on improvement after a new fuel pump. Maybe see if those symptoms describe your truck.

https://www.tacomaworld.com/threads/big-difference-after-fuel-pump-recall.720729/

 

Unfortunately, nothing like I'm experiencing. Thanks for the link. My stutter issue is not under any substantial load. It's most noticeable during low acceleration town driving when following other cars and the truck is toggling between 3rd and 4th without a down shift to accelerate faster.

 

try resetting all the learned values. My truck was doing something similar before I did a reset. You will need a birectional scan tool to do it or the dealer can do it via techstream. my truck also runs like garbage on regular fuel.

 

First thing I would try is make sure the ATF level is correct, and not overfilled/underfilled, this is important for these electronic AT’s. This is also when the majority of damage is done and one of the main reason manufacturers deleted the dipstick and filled it with lifetime ATF. It also needs the correct fluid, TOYOTA WS ATF.

I would definitively not flush the A/T at this time, only upon new replacement, if necessary.

If ATF level is ok, I’d try a good quality ATF conditioner. If that does not help, I’d try an A/T specialty shop and get their opinion.

The A/T shop will be best to advice on the torque convertor, my personal preference it to replace it too, and flush lines and coolant at time of A/T replacement.
Your truck is relatively new in mileage at 93k for this type failure, you should get another 200k+ easy if properly maintained .

 

Late 2017 are. I got a letter.

 

91,000? IMO, you should be on your 3rd drain and fill or on your 2nd full fluid replacement(not to be confused with a flush). Tough call now... maybe dump a tube of Lubeguard in there.

 

I would drain and fill the transmission with the proper fluid myself. Send a sample of the old fluid in to be tested. If someone changed the fluid at some point and put the wrong kind in or left it low that can cause issues. Also if your scan tool can monitor PIDs you can watch the engine RPM while it is doing it and try to verify it is the transmission and not the engine. If the RPM is jumping up and down it could be an engine performance issue. What the tech meant by clutch pack is the clutch drum has a few friction discs and steel discs. They are contained in a clutch drum with a thick plate on one end and a piston with seals on the other end. The purpose is to lock the drum to the shaft once engaged. Low pressure could be a leaking seal on the piston, worn oil pump, or simply low on fluid. Since it’s happening at low RPM the pump is not turning as fast and it will be less tolerant to low fluid level or internal leaks.

 

If it were mine it would be headed to auction before it reached 100K and took a value hit.