Superteeth

Hello everyone. I noticed something strange today while driving to work. I was driving at about 60 miles per hour, and as I approached a downhill section of the road I let off the throttle to keep from accelerating past the speed limit. The engine speed at the time was around 2000 RPM. When I let off the accelerator, the engine speed dropped to about 1000 RPM and stayed there until my speed decreased enough for the transmission to downshift (the car is a 7AT). As far as I remember, that has never happened before. I tried it again after driving at a constant speed of 50 miles per hour, and the same thing happened (a drop to about 1000 RPM). I was not using cruise control, if that is relevant. Is this normal, or is something wrong?

JSolo

iTrader: (14)

What were you expecting to happen? Isn't the idea of the 7at to stay in the highest gear possible for as long as possible to get best mpg/economy?

Superteeth

I know that. However, as far as I know the car was already in 7th gear. I checked by attempting to use the paddle shifter to upshift. The display simply showed that I was already in 7th gear.

Superteeth

Alright, here is a correction. The engine speed does not drop to 1000 RPM from 60 miles per hour, but it does do so from 50 miles per hour. I also found a way to get this to happen somewhat reliably: If I am decelerating without the brakes from, say, 55 to 50 miles per hour, then lightly tap the accelerator, the engine speed suddenly drops from 1500 RPM to 1000 RPM and stays around there until I stop. Also, the drop in RPM almost feels like shifting into neutral, but the engine speed goes to 1000 rather than the idle speed (about 750 RPM).

~Lefty~

iTrader: (1)

All I can think of is go in for a transmission & ECM update.

Superteeth

Have there been any updates since the 2012 model?

TVPostSound

iTrader: (9)

Sounds like the torque converter locking, allowing for better engine braking.
I wouldn't sweat it.

~Lefty~

iTrader: (1)

Could be. Doesn't hurt to check. You should be able to call with your VIN handy.

Superteeth

Better engine braking would occur at higher RPMs, right? When I tap the accelerator while slowing down, the engine speed drops, it does not go up. Most importantly, why is the torque converter locking while I am decelerating rather than while I am cruising? I thought the point of the torque converter was to increase efficiency.