I have a 2001 Supercrew, 5.4L, 4x4, 3.55LS, w/ 4R70W, and 7000 miles. Question is, when running 55 or above , on expressway, I let up on the downhills and the truck runs away. Then when I accelerate at the bottom of the hill, the engine revs like the torque convertor is not locked up. After 1/2 second or so, the convertor locks and the revs come back down. I can sometimes see 400 rpm jump on the tach. Is this normal? I can see the torque convertor unlocking letting the truck coast to increase mileage, but how many rpm should it run past to lock again? Any body else notice this?

TIA,
randymechanic just not on transmissions.

 

When I've travelled the Blue Ridge mountains around I did alot of coasting down them. I did not notice an rpm jump when I got back into it. If you got into it hard again accellerating, then I'd say yes, that's "normal" due to the soft shift of the tranny program. Maybe it's service time for you.

Fine print. My thoughts, in which by no accounts should be taken as "the word".

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