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Old 10-01-2013, 08:58 AM
TransEngineer TransEngineer is offline
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I suspect that what you're noticing is Decel Fuel Shut-Off (DFSO), which cuts all fuel to the engine while you're coasting. I don't know for sure whether the 8-speed uses DFSO, but I would think (since it's aimed at increasing your fuel economy) that it does.

Since the engine needs to be kept turning (even when fuel is shut off, to avoid bumps / jerks / etc. when you step back into the gas), the Torque Converter Clutch (TCC) is kept locked during DFSO. In higher gears, as you slow down, the engine speed would fall below what is needed for a smooth "re-start," so that is why the transmission downshifts as you slow down. It is just keeping the engine speed within a certain range to ensure good response when fueling resumes.

If you don't like the "draggy" feel when coasting (I personally don't like it either), you can shift the trans to Neutral (while coasting), which should give you a "normal" smooth coastdown. As long as the engine remains running (so that the trans has lube pressure), coasting in Neutral should not harm the transmission. But don't coast in Neutral AND turn the engine off; that is NOT a good idea.

Now as noted, I can't say for SURE that this (DFSO) is what's going on, but that would be my bet...
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