[HD] Automatic transmission, rough and delayed shifting from gears 2+
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Thread: Automatic transmission, rough and delayed shifting from gears 2+

  1. #1
    Newbie Bigemot has not yet proved knowledgeable
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    Jun 2010
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    Default Automatic transmission, rough and delayed shifting from gears 2+

    Hi everyone,


    I went to the dealer with this, they test drove it and said that nothing is wrong. Is this really normal, or am I going crazy?
    Here is the problem --

    The car shifts perfectly from gear 1 to 2. However, from 2 to 3 and from 3 to 4, the shifting seems delayed and the car slows down... and then sort of lunges forward.

    An analogy for this in a manual transmission: in 2nd gear, push in the clutch, gas it more than you should, shift to 3rd gear, release clutch -- the car jerks forward. That's exactly how my car sounds and feels when shifting.

    This car only has 8,500 miles (2010 model) and has had two oil changes and the 7500 mile maintenance service.

    I am hesitant to go back for a second opinion, unless I can find some good way to approach the mechanics with this problem, if it's familiar to anyone... Maybe I didn't explain it well the first time, but it's hard to miss (passengers notice it also).


    Thanks for any help or info, anything is helpful!
    Bige



    Edit

    Sorry, after some more digging through the threads, came across this:
    Quote Originally Posted by cclngthr View Post
    The automatic HD cars normally will do this. The fuzzy logic in the TCU holds the shift a bit longer to prevent abrupt and frequent shifting. 15 mph is right at the point where 2nd gear is coming into action so the car will hold 2nd gear depending on throttle response.

    Mine does this all the time. I put it in 3rd gear while driving in town to prevent a buck issue.
    Source thread
    I guess this helps explain my shifting, which is a relief even if the "problem" still exists -- I still wonder if the rough shifting is hurting the tranny.

    Oh, another thing (can't believe I forgot to mention this): when accelerating quickly, and the gear shift occurs at 3500+ RPM, it shifts smoothly. It only jerks when I accelerate slowly!
    Last edited by Bigemot; 01-20-2011 at 07:01 PM.

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  3. #2

    Default Re: Automatic transmission, rough and delayed shifting from gears 2+

    This is because the TCM is attempting to prevent overshifting. At light throttle, the trans normally would upshift very quickly from gear to gear, and the repeated shifting can damage the internals, so what manufacturers do is put a delay into the shift so the trans does not shift too frequently. Even my Mazda 3 does it.

    "Childhood is measured by sounds and smells and sights before the dark hour of reason grows"John Betjeman

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