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DFM Vibration after lifter replacement

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I have never detected any vibration, shudder, shift point change or shifting smoothness change on either my 2007 Yukon (5.3L FF, AFM) or my 2022 Sierra AT4 (6.2L, DFM).


I have read enough reports of such things by very credible posters, to know it is real.  I have never heard an explanation of why some trucks exhibit it or even what the source of those symptoms might be.

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We also have a '21 Silverado DFM 5.3 8-speed truck that had lifter replacement. It vibrated the same before and after the replacement, especially cruising at specifically 31 MPH prior to shifting up a gear. I can't stand DFM so I drive the truck in L7 to disable it and it's much smoother at all speeds.

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