Hey Scotty, I Have A 2013 Chevy Sonic LT 1.8L with 60,000 Miles, The Transmission Was Leaking A Bit Of Fluid And A Friend Of Mine Changed The Fluid Because It Was Dark Already And Needed A Change, But He Also Added Bar's One Seal To It To Stop The Leak And It Was Running Good Until After A While Of Driving It Shifts Rough When I Come To A Stop And Accelerate, It Only Does It After I Drive For A While, But If I Drive It The Next Morning It Does The Same, Shifts Good At First But Then Starts Shifting Rough After Driving It For A While.... What Should I Do? Please Help
You need to fix the leak first. After that, change the fluid and filter, and do not add any additives.
Take it to a transmission specialist for diagnosis.
A Friend Of Mine Changed The Fluid
Did he use genuine Dexron VI fluid?
Did he also replace the filter?
Was it flushed?
And did he reset the adaptive learning values?
Bar's One Seal
Additives are for when you're NOT planing on keeping the vehicle long term.
Obviously, this was a very bad idea.
Shifts Rough (...) It Only Does It After I Drive For A While
Either your transmission is overheating, OR
Rough shifting is the typical sign of a worn out valve body.
I do not know where the additive has polymerized inside of the tranny.
But I suspect it's either messing with your heat exchanger or the valve body.
What Should I Do? Please Help
- Replace fluid again
- Use genuine GM fluid compatible with your transmission!
- When replacing the fluid, do not forget about the filter!
- CHECK the magnets and for anything inside of the fluid.
- After replacing the fluid, VERIFY the fluid leve.
- RESET the car's computer in hopes of reseting the TCM
- IF POSSIBLE / Drivability not restored, PERFORM adaptive value relearning.
- Connect a scanner, drive and monitor transmission temperature.
- IF it runs very hot (above 110C), investigate the (rad/exchanger)
- IF it shifts rough, it's time to rebuild (rebuild valve body and hope for the best OR just replace the whole unit with GM refurbished, but at that point I'd just live with it)
Welcome to GM cars, where everything is that much harder than it should be.
won't the adaptive values ... adapt?
They do adapt to transmission wear and tear,
But a lot of the crappy ones do not adapt well to when the ATF is neglected and then replaced.
Too much has changed for the transmission to adapt in a reasonable time, it may adapt it may not.
-
(Although I'm unsure whether a GM conventional auto does it this way, I think they use the learning procedure to measure actual physical properties of the fluid and transmission internals and use them to calculate parameters that'll be used to shift smoothly,
But generally, modern, Sophisticated TCMs are programed to mainly optimize parameters using an algorithm that gathers data from previous attempt. At each attempt, it gathers information on how smoothly the shift was done, and as such attributes a "reward" using assessments of how smooth the operation was ("reward function").
This process of "Reinforcement learning" using "Gradient descent".
The software will try to optimize the "reward function" (Aka smoothness), but the way they're built, they're likely to not find the absolutely best parameters, and instead "land" on parameters that seem to be the best in the scope it is able to check (local maxima / minima of the "reward function" as opposed to global maxima/minima) - as that's what iterative optimization algorithms are usually used for in ML.
And here too,
if things change too much, it is likely to get stuck at a false maxima/minima ("get stuck on a false hill")
And it will not be able to optimize and adapt in a timely manner.
So a lot of the time, performing adaptive learning is the way to make an odd shifting tranny shift right again.)