Automatic transmission dont shift when warm
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  1. #1
    Neutral
    Join Date
    Apr 2008
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    5

    Automatic transmission dont shift when warm

    Dear friends

    I have just parchased my Passat 1.8T triptronic with 102 k.
    The dealer have made all the service that are in manual service, including
    replacing the turbo. The problem is:

    When the engine is cold, the transmission shift normally without any problems. When the engine starts to heat , say 20 to 30 minutes in transit, the shifts starting to be more difficult, where sometimes the speed starts to increase without any shift, and at other times the speed begins to fall, requiring a kick down in order to restore the speed.
    Could you please give me a explanation about this problem..?
    Sorry my mistakes, but English is not my native language.

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  3. #2
    4th Gear
    Join Date
    Nov 2005
    Location
    Arizona
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    3,559
    Welcome to Passatworld.

    Which one of these things happens after the car is warmed up, when you accelerate from a stop, the transmission stays in the gear too long and does not upshift when you think it should upshift or do the rpms go up but the transmission does not upshift (transmission is slipping)?

    Also, when you are slowing down and then start to accelerate again does the car fail to downshift as you expect or is the torque converter not unlocking (rpms do not go up several hundred rpm)? and you have to use the kickdown switch (floor the accelerate pedal) to get it to downshift?

    Two things come to mind: first are you in normal driving mode or in tiptronic manual mode when it does these things? That is do you have the gearshift lever to the left in "D" (normal mode) or to the right side where the + and - labels are? If you are in normal mode how does it shift manually in tiptronic mode? Are the manual upshifts and downsifts crisp or are there delays in shifting to the next gear?

    Secondly, if the transmission is slipping and not shifting properly when hot, your transmission fluid may be low. Unfortunately, you cannot easily check the transmission fluid level. See this link on how to change and check the ATF. http://www.taligentx.com/passat/maintenance/atfchange/

    You may want to go back to the dealer and show them what is happening and see if they will check the ATF level for free since you just bought the car.

  4. #3
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    Apr 2008
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    Kenblasco
    These things happens after the car is warmed up in drive mode. Tiptronic works fine, though the downshift only occur when the rpm goes to limit.
    When the transmission is in the gear too long and then I must to accelerate supose for a rising, the transmission does not upshift, loosing speed while I don’t make the kickdown.

    Some times the transmission don’t downshift when I drive in a small slop, rising the rpm until the slop is finished.

  5. #4
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    Apr 2008
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    I forgott to say that the transmission fluid was checked in Januar, completed and is OK

  6. #5
    4th Gear
    Join Date
    Nov 2005
    Location
    Arizona
    Posts
    3,559
    Again if I understand, if you start to go up a hill in drive mode and you accelerate to maintain your speed up the hill, the car starts to slow down instead of maintain speed. So if you don't kickdown to drop into a lower gear, the car loses speed. It sure sounds like your torque converter does not know when to unlock. The fact that the rpms rise when you go up a small slope (assuming you are accelerating to maintain speed) indicates that the torque converter does unlock like it should at least at those times.

    The transmission control module (TCM) gets data from the engine control module (ECM) and internal transmission sensors to determine when to lock and unlock the torque converter based on engine torque requirements among other things. You may want to find someone with a VAG-COM to scan the ECM and TCM for faults. The transmission does use the engine coolant temperature sensor also as an input (not the same sensor element as the temperature gauge reading). There was a recent post where the other person was having issues with shifting although his issues do not sound like the issues you are having and replacement of the sensor solved his problem. Again with a VAG-COM you can monitor the coolant temperature to see if the sensor is working properly.

    Also, I don't have a 1.8t so I don't know how that might affect tranny shifts vs the V6.

  7. #6
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    Join Date
    Apr 2008
    Posts
    5
    kenblasko

    tks for information. I returned now from dealer, and we check with Vag.Com
    the codes. We dont find nothing wrong, but we reset the codes to monitor again the car. If the problem appear again, I will check the sensor.
    tks.

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