07 CTS with 18k miles seems to shift strange... It just seems to me that it shifts into 4th and 5th gear way too soon. To the point that it almost makes the engine lug a little. Surely this isn't normal right?
tcc is torque converter clutch. When it is applied, the transmission doesn't slip. Its fully connected or almost to the engine so it means less friction, less heat, better mpg, longer the transmission will hold.
the 5th gear at 38 mph, I think too its ridiculous but thats the way it is design.
The Sport mode only holds the current gear longer before upshifting. Meaning if your in full throttle with sport mode activated lets say at 80mph and suddenly, you let off your foot of the gas pedal, it will hold the 4th gear instead of shifting into 5th gear. So it helps you for better performance during cornering. It doesn't go higher in the rpm when full throttle though.
When in sport mode, you'll see that at 38mph, you'll stay in 4th gear. At around 43-45 mph, it will shift into 5th.
I long thought that I had 6 gears including overdrive when I was counting the shift through the rpm drop. When I plugged a tech2 scantool, I saw that the tcc was applying between the 3rd-5th gear during light and normal throttle for better fuel economy and less heat into the transmission.
For me, just the opposite. I think it waits too long to shift into 5th. My will absolutely not shift into 5th until just before 40 mph. Which seems unnecessary to me when 4th gear power is not needed when cruising around 35 mph.
To counter it, I just accelerate to 40, then back off to 35, and the car seems quite happy in 5th. And it wont down shift until I get close to 30, or give it a lot of gas pedal.
And I too have noticed almost NO difference at all between drive and sport. Unless I use the shifter. Even then it does not hold gears very well. Manumatic is simply a placebo in this car.
Hi, I have an 06 Lux pac, and I have had the same "lugging" issue. First time the mech's said "no problem found". I then spoke to service manager, he took it out and diag the LUGGING and suggested a recalibration of the shift points, this did not fix problem. They then replaced the torque convert in May. Yesterday June 25th on my way to work I saw a huge cloud of smoke in my rear view, the tranny blew up. 69k kilos, thats about 45k miles. Not many! Now I am fighting to get new tranny, don't want this on rebuilt!!! After 30 years of all GM loosing faith. More times to dealer with this than my last 3 cars combined. Perhaps it is the quality of the mechanics and not the product I am not sure.
Go to any auto forum, including Lexus, Toyota, Honda, etc.. you will find plenty of posts just like yours.
Not to diminish your situation, I would sure be upset too were I in your shoes. But it happens with all makes of cars. You just happened to be the guy who got the bad one.
You just have to fight the good fight, and hope it all works out. I wish you the best.
btw, my boss just bought his son an Acura TL with 100k miles a few months ago. Then found out the car was on its third transmission.