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Throttle up problem on Taco V6 MT on dpressed cluch

Discussion in '2nd Gen. Tacomas (2005-2015)' started by dprender, Jan 21, 2010.

  1. Jan 21, 2010 at 6:02 AM
    #1
    dprender

    dprender [OP] Member

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    Quick survey to see how big this problem is. if you have a Manual trany, please respond yes - if you RPM goes up when you press the clutch especially when accelerating - No - if RPM is always normal.

    Thanks
     
  2. Jan 21, 2010 at 6:08 AM
    #2
    jester156

    jester156 Well-Known Member

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    YES,
    seems to rev a bit when coming to a stop with the clutch depresses. I hear this is an emissions "feature"

    edit: just reread your question, and YES this seems to happen as well when accelerating, but now I have a short throw shifter so I get through the gears quicker.
     
  3. Jan 21, 2010 at 6:10 AM
    #3
    Afwrestler1986

    Afwrestler1986 Well-Known Member

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    Just a counter question.......How is this a "Problem"?

    It would make sense to me that when accelerating your RPM's raise.
    When you remove your foot from the accelerator the engine is going to take X amount of time to idle back down to normal idle speed.
    So if you run your engine up to...oh ....say 5k RPM's and put your clutch pedal in while removing your foot from the accelerator, the resistance from the transmission is taken away and you are left with a much lower resistance to the engin, thus causing your RPM's to raise. Couple this with the drive by wire system and the results are a slightly more delayed reaction of the engine idling down.
    My 1st gen 5 spd does the same thing. The effects are less noticed by the fact that i have a cable commanded throttle.
     
  4. Jan 21, 2010 at 7:11 AM
    #4
    dprender

    dprender [OP] Member

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    Thanks Jester156

    To answer wrestler's question

    I had a 1995 Taco MT 5 speed V6 3.4l as well and never had this problem. So when I bought a 2010 it was the first thing that I noticed as being out of the ordinary as compared with my old truck.

    If it was just a small increase in RPM it would not be so annoying. Shifting at around 2-2.5k while accelerating from a stop, the rpm jumps by 500 to as much as 1100 RPM when the cluch is pressed between shifts. I assure you that my foot is not on the gas. Sometimes I intensionally remove my foot from the gas before presssing the cluth to see if it is me. Seem abit abnormal and is annoying to me and I bet to the people who hear me leaving the stop.

    When there were springs cables and screws like my old truck, this did not happen, The computers on these trucks can react much faster and can detect the slightest change in engine resistance doing this even before the driver is finished pushing the cluch in.The computer should then command the engine to throttle down not up. Its a feedback control problem in my opinion, The feedback loop seem to be under dampred and it should be critically damped.

    Any opinions?
     
  5. Jan 21, 2010 at 7:18 AM
    #5
    Afwrestler1986

    Afwrestler1986 Well-Known Member

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    If you are sitting stationary with the truck idling in neutral, and you press the clutch in does it still do it?
     
  6. Jan 21, 2010 at 7:20 AM
    #6
    98tacoma27

    98tacoma27 is gooder 'en chicken Moderator

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    It's programmed to do it. The autos act similar.
     
  7. Jan 21, 2010 at 7:27 AM
    #7
    dprender

    dprender [OP] Member

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    No its perfectly normal when idling. Its good to know that the MT autos do it as well
    More responses would be great.

    Thanks
     
  8. Jan 21, 2010 at 7:29 AM
    #8
    TacoCat

    TacoCat Look away, I'm hideous!

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    Mine does. It's annoying.
     
  9. Jan 21, 2010 at 8:20 AM
    #9
    SManZ

    SManZ el tráfico más lento se queda derecha

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    Mine does this too. I'm hesitant to go for a short throw shifter since right now the long shift throw matches up with the time it takes for the revs to drop for a smooth upshift.

    Would URD pulleys help the motor spool down faster?
     
  10. Jan 21, 2010 at 8:26 AM
    #10
    xodeuce

    xodeuce mmmmmmbourbon.

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    Going to a lighter weight flywheel will have the biggest impact on how quickly the engine gains / drops revs. Pulley's might help. Anything that's rotational mass. However, inertia is your friend when you're feathering the clutch, particularly offroad. It's easier to stall an engine with very little rotational mass, because you you don't have the inertia to keep it running.
     
  11. Jan 21, 2010 at 8:53 AM
    #11
    PSUnick

    PSUnick Lets Go State!

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    I agree that I think it is a control problem, and not a mechanical inertia problem. I am not sure that it is an underdamped system, however. When in gear and maintaining speed, there doesn't seem to be any lag between when acceleration is commanded and the engine responds. Acceleration (increase or decrease in speed) seems relatively instantaneous, implying a fast rise time on the control loop, and not an overly underdamped system.

    However, the problem does exist that when the throttle is cutoff completely, and a shift is engaged to allow the motor controller to dictate rpm rather than the transmission, that the rpms hold value, and can even accelerate, for a good second or two. It seems to me that the controller ignores a sudden change in input signal, and it holds the previous value for a second or two. Moving average on the input signal?

    Just my initial thoughts on this.
     
  12. Jan 21, 2010 at 9:20 AM
    #12
    PSUnick

    PSUnick Lets Go State!

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    BTW, my fix for this is letting off of the throttle completely before I begin to depress the clutch. It seems to work well. By shifting normally and letting the rpm's rev up every shift is going to wear out the clutch in no time.
     
  13. Jan 21, 2010 at 9:41 AM
    #13
    Chester

    Chester Well-Known Member

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    My roommates 99 does this as does my 07.You get used to it.And I doubt the clutch worry has merit.My roommate swapped his out a 130k.Its all in how you drive,if you sit and stress at every shift then yes your going to kill your clutch.
     
  14. Jan 21, 2010 at 10:01 AM
    #14
    BRP27

    BRP27 When I grow up I want to be just like Me

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    I have an 04 V6 Tacoma with a manual 5 speed. When shifting at less than 3000 it shifts normal( no rpm increse). Push the clutch in at idle no increase. But if I rev it past 3000 to shift it is seems to rev up between gears. If I let off the gas just before I shift it does revs down and shifts more normal. It is very ackward to shift when you are on the throttle.

    I have a new 09 Honda Civic Si with a manual 6 speed and it holds the rpm up between shifts ( for emmisions) but the Taco seems to rev up between shifts. I have looked at the RPM on the Taco when shifting above 3000 rpm and I don't see an rpm increase but it sounds like it increases and it is annoying. I have gotten used the the Honda and have had both the Honda and Taco for about the same amount of time. I have yet to perfect a hard accelleration shift on this truck. So I tend to drive it slower.
     
  15. Jan 21, 2010 at 10:29 AM
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    leochup

    leochup Well-Known Member

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    Yes, mine does it aswell I wish their was a tunner that could could fix our problem.
    I Read here in TW that it was engineered that way to burn the excess in gas, for cleaner emissions
     
  16. Jan 21, 2010 at 11:04 AM
    #16
    dprender

    dprender [OP] Member

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    I agree with your thoughts on the damping somewhat, maybe its a combination of damping factor and hysterisis in the control loop. Hard to say, I think they could do a better job with more attension to this aspect. Its a good expanation for excessive over reving.

    It sounds reasonable to allow for a small (couple hundred) increase in RPM to burn excess fuel if that is what is hapenning but increasing by over 1000 RPM between shifts seems excessive to me. Anybody see RPM increases that high? My truck is only 5 weeks old, I wonder if that has anything to do with it.
     
  17. Jan 21, 2010 at 2:08 PM
    #17
    Robbie 09

    Robbie 09 Member

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    My '09 with the V6 does it. I had a '99 with the 3.4L before this one and it was fine. I do the same thing a previous member mentioned, I release the gas a little before depressing the clutch to get away from the revving issue.
     
  18. Jan 21, 2010 at 2:51 PM
    #18
    putawaywet

    putawaywet Yaris Offroader

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    My 2010 V6 MT does it too. My 2000 I4 MT did not. I don't particularly care for it, either. If it is an emissions thing, I guess it is what it is and we just have to live with it. FWIW, my wife's 2010 Subaru Impreza does the same thing, but not quite as bad as my Tacoma.
     
  19. Jan 21, 2010 at 3:30 PM
    #19
    saltwater taco

    saltwater taco Well-Known Member

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    mine doesnt.
     
  20. Jan 21, 2010 at 5:27 PM
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    PA452

    PA452 Well-Known Member

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    When I first got my 2007 Tacoma, I was really pissed about this. Two main reasons:

    1. I never drove a vehicle before that did that, and it threw off my normal style of shifting.

    2. If I was slowing down while in gear, at some point the computer would decide I was moving too slow for that gear, and it would automatically give the engine more gas, giving me acceleration when I really didn't expect it.

    I took the truck to the dealer and complained about it. They said they never heard anyone else complain about it before at that time. I went for a ride with a service tech, and he admitted he noticed it and did find it a little annoying. He also noticed the automatic acceleration, and admitted it kind of surprised him.

    In the end, I got used to both.

    Interestingly though (to me anyway), the truck really does "learn" your driving style to some degree. I had read that that was the case, but thought I primarily adjusted to it. Well for I think the first time since I bought the truck, I removed a battery terminal for an hour a couple weeks ago to reset the ECU for a fuel octane experiment. I swear the next time I went out on the road, it was like driving a different truck. Seems back to normal now, but I definitely noticed a substantial difference the first couple times I had it out on the road after the ECU reset.
     
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