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Startup engine idle speed

Discussion in '2.5 Gen Tundras (2014-2021)' started by Eaganite, Nov 29, 2020.

  1. Nov 29, 2020 at 7:14 AM
    #1
    Eaganite

    Eaganite [OP] New Member

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    I've found this interesting, and am curious about how other trucks act.

    When I first bought my truck, mid March I noticed when starting the cold engine it would instantly reach 1600rpm, then of course idle speed would start to fall. But recently I've been noticing that the cold start idle speed is like 1400rpm. I always felt that 1600r's seamed kind of high, not that 1400r's is a lot slower but it is definitely noticeable.

    The thing that's curious is how did this slower startup speed manifest its self? My thought is maybe part of a software update downloaded by the truck. I have had updates show up on the main display on the dash that I accepted and installed, is that possible?
     
  2. Nov 29, 2020 at 7:23 AM
    #2
    tttrdpro

    tttrdpro Former Naval Person

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    I thought those updates were for Entune only but I could be wrong. Is it possible the dealership updated the ECU when you were in for something else?
     
  3. Nov 29, 2020 at 7:24 AM
    #3
    Sunfish

    Sunfish New Member

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    My 17 starts with enthusiasm but quickly scales back to about 1000 rpm and then finally on back to around 700. The outside temperature could have something to do with the start cycle
     
    Last edited: Nov 29, 2020
  4. Nov 29, 2020 at 7:29 AM
    #4
    Zero One Actual

    Zero One Actual Member among Members

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    My 19 does the same thing. I just figure with how many Gen 3 Tundras there are with the exact same engine and nobody else worrying about it that it’s normal. Kind of like the clicking sound or the bump when first starting. Or like your ankles if you are older. Hahaha.
     
    Gunship Guy likes this.
  5. Nov 29, 2020 at 7:59 AM
    #5
    Eaganite

    Eaganite [OP] New Member

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    Agree thinking those updates for Entune, and I did have the truck at the dealer 9/15 for a wheel alignment check and they did the turn signal wire fix. But I would think if they did any software updating it would have been documented in the paper work.
     
  6. Nov 29, 2020 at 8:10 AM
    #6
    Eaganite

    Eaganite [OP] New Member

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    I also realize ambient temperature would play a roll, but living in "Minnesnowta" its cold here a lot. Certainly in mid March and October, November overnight temps can get rather chilly.

    This isn't something that's concerning me, just a curiosity more than anything.
     
  7. Nov 29, 2020 at 8:34 AM
    #7
    Wynnded

    Wynnded What MPG...

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    I've upgraded to my truck to the Auto Climate Controls, but I've noticed that until the engine is at full operating temperature, the revs will stay elevated somewhat if the Climate controls are set to Defrost and/or Auto. If I'm sitting there in P/N and partially warmed up, I can press Auto/adjust Defrost on/off, and the revs will increase when these functions are on. Play with that on yours just to see if the same thing happens.

    Additional thing that I noticed: When the revs are slightly elevated pre full operating temp, I've noticed that when I place the transmission in gear, the computer will lower the revs so the truck won't "bang" into gear.
     
  8. Nov 29, 2020 at 8:52 AM
    #8
    Eaganite

    Eaganite [OP] New Member

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    I believe the change in engine speed when engaging Auto or Defrost in the climate controls, is because of the compressor engagement.
     
    Wynnded likes this.
  9. Nov 29, 2020 at 8:54 AM
    #9
    tttrdpro

    tttrdpro Former Naval Person

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    Yep
     
  10. Nov 29, 2020 at 8:55 AM
    #10
    Wynnded

    Wynnded What MPG...

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    I used Techstream to restrict the A/C to only come on with an A/C button press. It will not come on automatically under any circumstances.
     
    TTund16 likes this.
  11. Nov 29, 2020 at 8:57 AM
    #11
    Eaganite

    Eaganite [OP] New Member

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    Now that is something I would love to have done with my truck!
     
    Wynnded[QUOTED] likes this.
  12. Nov 29, 2020 at 1:24 PM
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    TTund16

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    Does the A/C light or LED come on every time AC is turned on automatically? I mean before your techstream tweak.
     
  13. Nov 29, 2020 at 1:27 PM
    #13
    ItsNickROFL

    ItsNickROFL New Member

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    Intake, exhaust, interior
    So somewhat similar. Looks from your account it’s a 2020 just like mine. I have less than 4K on my odometer but I installed an exhaust and a intake. Mine kinda went down after doing so I figured the ECU adjusted for everything properly and didn’t need to idle as high. But I would consider as you’ve “broken in” the truck maybe it’s mapped the idle speed bwtter?
     
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  14. Nov 29, 2020 at 1:32 PM
    #14
    Wynnded

    Wynnded What MPG...

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    It did, yes.
     
    TTund16[QUOTED] likes this.
  15. Nov 29, 2020 at 5:47 PM
    #15
    Eaganite

    Eaganite [OP] New Member

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    Hadn't considered startup idle speed slowing after engine break in. I have about 5600 miles on it now, maybe your on to something.
     
  16. Nov 29, 2020 at 6:17 PM
    #16
    gupster88

    gupster88 New Member

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    Cold engine start my truck always revs higher in RPMs for maybe 30 seconds before it idles down some. Doesn't matter if it's hot or cold outside, fan on or off, AC on or off. All my Toyotas have done that I just thought it was normal.
     
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  17. Nov 29, 2020 at 6:27 PM
    #17
    jwatt

    jwatt I heart men

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    I m not too fond of that crazy loud fan at startup, but when I turn the key it s like it cant wait to start. It s almost startling sometimes.
     
  18. Nov 29, 2020 at 6:33 PM
    #18
    stuckinohio

    stuckinohio MGM Crue

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    I agree with Nick's comment regarding the ECU. When you install any aftermarket intakes, they recommend you disconnect the battery.
    This step performs a few things, but it will clear the long term fuel trim map file.
    When a truck is brand new , it is still learning and writing the fuel trim file.
    Once that file is established, it will be referenced to help optimize start-up and idle.
    When comparing cold-start to cold-start, is it at the same weather conditions and temperatures? or just cold?
     
  19. Nov 30, 2020 at 5:14 AM
    #19
    Eaganite

    Eaganite [OP] New Member

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    I was just comparing the cold start initial rpm speed, not taking specific temperatures or weather conditions into consideration. Nothing scientific and I haven't disconnected the battery, at this point Nick's thoughts on the ECU adjusting start up speed seem the likely scenario.
     
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  20. Nov 30, 2020 at 6:20 AM
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    Vizsla

    Vizsla ☠️☠️☠️

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    These are what I have available in the ECU regarding idle rpm and airflow on my 2018. 3rd picture I opened the Base P/N(park/neutral) table, coolant temp in white numbers, target idle speed numbers in color below.
    FD2D7846-AA0F-440D-B5AB-4DDE7FE4E168.jpg
    EBC1CA37-A0C7-4033-88DB-B24CAAC10B0E.jpg
    3BE4CD47-E56D-48D5-9AE8-0699203F35AB.jpg
     
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  21. Nov 30, 2020 at 6:35 AM
    #21
    Rider0120

    Rider0120 New Member

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    I think all Toyota’s have the high idle. Hell my grandmothers 94 Avalon has the same high idle startup, kind of annoying but at least you know the major components are warmed up before you start driving
     
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  22. Nov 30, 2020 at 6:47 AM
    #22
    Eaganite

    Eaganite [OP] New Member

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    [​IMG]
    Assume temps in Fahrenheit?
     
  23. Nov 30, 2020 at 7:04 AM
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    Vizsla

    Vizsla ☠️☠️☠️

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    Yes
     

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