When does my automatic shift gears?

[newhavenpatriot]

Hey all, I just read my owner's manual and it doesn't tell me when my automatic transmission shifts gears. Is this because it's different every time? It showed when the manual version of my car should be shifted up or down, but there was no information about the auto version. I wish I could find a graph specific to my car that shows me the ideal speed I should cruise at for the highest mileage.

[Peter7307]

Possibly the new transmissions "learn" the driver's style and adapt the shift patterns accordingly.

Pete.

[IsaacCarlson]

I pulled a 2,000 lb trailer last week and my shift points changed a little and the fuel trims, etc also changed so mileage is still coming back up. I had a sunfire for a while and it would run to about 4,000 rpm for the first two gears for about 4-5 take offs if you got on it hard once. But it wouldn't give it everything that one time because it had been driven slow. really drives me nuts because they don't like to do what you want them to do when you want them to do it. The olds is pretty good about it though. At least they learn to shift a little sooner if you are nice and easy...unless you have a manumatic, then you shift it when you want. i just have to get mine put together...

[Formula413]

There is such a thing as Isaac described, I heard it called "adaptive shift profiling" on a Mitsubishi Lancer once. Not sure how many cars have this feature.

As to when the car shifts, it is determined by engine load and RPM rather than vehicle speed. And for your ideal cruising speed, experiment and find out what the slowest speed you can get the torque converter to lock with the tranny in top gear is. It's usually around 35-40 mph. My Escort has trouble keeping the TC locked below 37 mph for example. If you are unsure whether your TC is locked or unlocked, get a reference by driving the car at, say, 60 mph on a level road and note the RPM once it has dropped as low as it will go. Than figure what that would translate to at 45 mph, 40 mph, 35 mph and see if it can achieve that RPM at those speeds. If the RPM is higher than what you calculated the TC is unlocked.

[Old Tele man]

...call the Service Manager at your local dealer, he/she should be able to quote the high-low "shift" points (mph, rpm) for your car...such information is listed in the transmission section of the factory Service Manual.