I notice that my 2007 3.0L automatic shifts extremely smoothly on every shift. Normally this is VERY bad for longevity in an automatic but I also noticed at easy throttle settings that the rpm drops momentarily very quickly then comes back up. I am wondering if the computer is de-fueling the engine just at the moment of the shift to minimize torque applied to the bands. This would go a long way to keeping the bands and or clutches from slipping during shifts which would improve longevity.


Does anyone know for sure if that is what is going on? I have driven a big rig truck with an automatic and it did exactly that. You mashed the gas pedal and held it to the floor and the engine would throttle back while the automatic shifted then it would throttle back up again over and over about 15 times as it went through the gears. From the outside you couldn't tell I wasn't backing off he gas and shifting like a manual transmission. Pretty cool actually..

 

Our 2.5 x-type has always done the same thing. It shifts so smoothly you have to watch the tach or listen to engine note to notice the shifts. Over 160k on it and no problems yet.

 

Gadzooks, you are right on both accounts. yes, the motor will back off slightly to minimize the load the tranny is seeing in them middle of a shift. But, the manufacturers also put a fair amount of slip into the tranny during shifting to make it that much smoother. Is it enough slippage to be worried about. I don't think so. I am up to around 165K miles on my car and no issues with the tranny. But then, I don't do a lot of high RPM shifting. So, that helps with the amount of slippage the tranny would see.