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  1. #1
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    Nitro 4Tec 3.3 stalls when braking

    I just purchased a Nitro 4Tec 3.3 and the engine runs pretty good on idle and full throttle. But when I apply the brake the engine stalls.

    The vehicle was slightly used and most of the other settings were off and needed to be adjusted.

    I also upgraded the radio to a new TQi with Traxxas Link, I didn't change any settings so something may need to be adjusted

    What should I do to get it to keep running while on brake?

  2. #2
    Marshal Double G's Avatar
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    Maintain good idle gap.
    The Super Derecho

  3. #3
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    Quote Originally Posted by Double G View Post
    Maintain good idle gap.
    What does that mean?

  4. #4
    RC Champion grizzly03's Avatar
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    Make sure the gap on the slide in the carb has .7mm to 1mm gap. When you apply the brakes does the slide (idle gap) get smaller?

    This page should help explain: https://traxxas.com/support/Factory-...-25-25R-and-33

  5. #5
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    I will check the carb slider tomorrow and update.

    What should the transmitter throttle switch be set at 50/50 or 70/30 for the Nitro 4Tec?

  6. #6
    RC Qualifier nebulous.cow's Avatar
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    50/50 is default. For my traxxas nitros, I have found 50/50 to work better than 70/30 when setting up servo ranges.
    Don't change this setting without properly turning the radio and car off and on a few times, and checking the setup when completed for proper ranges.

    Unless you have a good reason to, don't change it from 50/50.

    -Mike

  7. #7
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    Quote Originally Posted by nebulous.cow View Post
    50/50 is default. For my traxxas nitros, I have found 50/50 to work better than 70/30 when setting up servo ranges.
    Don't change this setting without properly turning the radio and car off and on a few times, and checking the setup when completed for proper ranges.

    Unless you have a good reason to, don't change it from 50/50.

    -Mike
    That is good to hear. That is what it is set at. The new radio was set to 50/50 and I didn't change it because I didn't know what it would do.

  8. #8
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    I checked and the carb slider gap does get smaller when the brake is applied.

    I am not sure what it us supposed to.look like so I am posting links to pics of the linkage overview.
    https://www.dropbox.com/s/nnnj32y1le...nkage.jpg?dl=0

    Carb with no throttle
    https://www.dropbox.com/s/ukyfbebeub...ottle.jpg?dl=0

    Carb with brake applied
    https://www.dropbox.com/s/6jbhmf5l66...aking.jpg?dl=0
    Last edited by tvr4; 05-26-2020 at 12:19 PM.

  9. #9
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    Here is a pic comparing the carb slider with no throttle and with brake applied
    https://www.dropbox.com/s/z3zy0l1bgm...rison.jpg?dl=0

  10. #10
    RC Champion grizzly03's Avatar
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    The carb slide shouldn't move when you apply the brakes.

    If you haven't adjusted the linkage when you upgraded the radio try adjusting the trim on channel 2 to give you a gap in the linkage. You want the linkage circled in red to have a small gap when in neutral. This way it won't stall when you apply the brakes.

    After you adjust the linkage (so there is a gap) you would adjust the idle screw if you need to raise or lower the idle speed.



  11. #11
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    Quote Originally Posted by grizzly03 View Post
    The carb slide shouldn't move when you apply the brakes.

    If you haven't adjusted the linkage when you upgraded the radio try adjusting the trim on channel 2 to give you a gap in the linkage. You want the linkage circled in red to have a small gap when in neutral. This way it won't stall when you apply the brakes.

    After you adjust the linkage (so there is a gap) you would adjust the idle screw if you need to raise or lower the idle speed.
    This is awesome! I am going to try this adjustment today.

    I did not see a trim adjustment on the TQi 6507R 4-channel transmitter. I do have the switch set to 50/50

  12. #12
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by tvr4 View Post
    This is awesome! I am going to try this adjustment today.

    I did not see a trim adjustment on the TQi 6507R 4-channel transmitter. I do have the switch set to 50/50
    If you have the Blue Tooth link module and the Traxxas app, adjust the setting in the app.
    Select the model, then go to Drive effects, then move throttle trim to get the required gap.

    If you don't have the BT module and app you would need to follow the menu tree to adjust.

  13. #13
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    I do have the Bluetooth module and will look for that setting.

    I did tinker with the linkage today and think I have it set or at least close. The carb slider does not change when I go from idle to braking. And high speed seems to be ok as the slider is full open.

    Only now it stalls occasionally on idle and the wheels slowly turn when on idle. I think it is an adjustment at this point since I was never able to adjust it before.

    1) Should the wheels be stationary on idle?

    2) What carb settings should I adjust so it runs properly on idle?

    3) It also seems that after running for a bit the engine is difficult to start.
    I keep blipping the throttle to keep it running but Could this be an overly rich high speed setting ?

    Thanks

  14. #14
    RC Champion grizzly03's Avatar
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    1. At idle on the ground the vehicle shouldn't move. If you lift the car in the air the wheels will turn.

    2. Here is some help for tuning your engine: Tuning-Your-TRX-25-25R-and-33-Engine-Best-Performance

    3. The Low Speed Needle and idle screw when adjusted correctly will control the idle.


    Here is the Link again for factory carb settings if needed or for good settings to start from when tuning.
    Factory-Carburetor-Settings-TRX-25-25R-and-33

  15. #15
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    Quote Originally Posted by grizzly03 View Post
    1. At idle on the ground the vehicle shouldn't move. If you lift the car in the air the wheels will turn.]
    Ah. I have the car sitting on a wooden block to make it easier to work on.

    I will try putting the wheels on the ground and see if it moves.

    What is the procedure to adjust the brake?

    Thanks

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