Slip in 4th

on my 2011 DCLB w 56k miles, automatic transmission, when I'm driving the rpm's skyrocket when it attempts to get into 4th gear. I'm not sure what is causing this and if its a serious/frequent problem.. help me out if u know.... thx

 

skyrocket? what rpms are we talking.

You do know that 4th gear has two states, 4th gear with torque converter locked and torque converter unlocked. With the TC unlocked (IE right after a shift or on an uphill) rpms will be higher than cruising speed / low load in 4th when the torque convert can lock up.

 

Bringing this back from the dead. Not sure if he ever figured it out but does anyone know what this could be?

Similar symptom here - about 25% throttle, between gear shift 4th to 5th (only that change), and not every time. The skyrocket he mentions is when it won't click into 5th right away so the engine RPMs will spike until it catches. Bad torque converter?

Changed the ATF fluid recently and it did not resolve the issue.

 

Has the transmission fluid level been verified?

 

Drained and filled per this guide - How to Drain/Refill Automatic Transmission | Tacoma World e.g., entered temp check mode to ensure, overflow slows to a trickle, measured amount removed and added.

 

I just wanted to check, incorrect fluid level can cause alot of issues so it's always the first thing I ask.

Any CEL or codes?

@gearcruncher any other suggestions?

 

My 2nd gen was doing the same around 4.5k rpm. It would rev then suddenly shift with a jerk. It ended up needing one of the shift solenoids replaced in the transmission. Local shop took care of it and the truck is almost to 200k miles and going strong.

 

A flare up in 4th gear is unusual for sure .
Be nice to know if it only happens cold ?
Next is mileage and codes ?
Catch it before it gets worse $$$$$$. Dont let it continue to flare in 4th
Take your foot off the gas and allow the transmission to work things out until you get a chance to fix this
Have you been keeping up with transission services ?

 

No CEL or Codes

Would explain why it's a single gear shift vs all. No shudder with the torque converter at this time.

Typically, when I first start driving (cold).
Currently at 107k, no codes
Absolutely, always let off and let it catch-up.
107k was its first change, fluid wasn't overly dirty or contaminated. No towing. Supercharged.

I'll grab a video this afternoon.

 

0:22 seconds in - https://www.youtube.com/watch?v=ezl6LYnTgjk

 

What size pulley are you running on your blower?

 

I have a manual so I am not much help, but you might try popping in here and seeing if anyone else with a s/c’d auto has had this issue. I think a shift flare is a more common problem when dropping pulley sizes, which is why I asked about that above. Good luck tracking this down

https://www.tacomaworld.com/threads/trd-magnuson-4-0-supercharger-tips-tricks-and-mods.518932/

 

Stock pulley that comes with the Magnuson Supercharger kit. No other performance modifications.

After some digging, other threads that seem relevant to this:

https://www.tacomaworld.com/threads/transmission-slipping.307378/page-2#post-7889583 - Fluid level issue mentioned (however mine was occuring prior to the fluid change, will double check)
https://www.tacomaworld.com/threads...n-4th-and-5th-automatic.725226/#post-25831520 - 6th post mentioning SC shift flare as 'well known', later 'PERFECT combination of load and throttle input you get what you describe, a shift flare.' given I get this around a certain amount of throttle does correlate.
https://www.tacomaworld.com/threads...-overland-tailor.759590/page-37#post-28258677 - tune related
https://www.tacomaworld.com/threads...ricks-and-mods.518932/page-2335#post-28489862 & https://www.tacomaworld.com/threads...icks-and-mods.518932/page-2151#post-27299571- tune related
https://www.tacomaworld.com/threads...n-4-liter-trucks.289913/page-15#post-22272423 - @gearcruncher 's post. I'll pursue the tune route prior to hardware fixes intiaially.

I'll be reaching out to @JustDSM to see about going down the tune modification route. I'll report back as well.