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smoothness of engine on/off transitions?

Discussion in 'Gen 2 Prius Main Forum' started by pasadena_commut, May 11, 2019.

  1. pasadena_commut

    pasadena_commut Senior Member

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    I have a "new to me" 2007. Question - how "smooth" are the engine on/off transitions supposed to be on a healthy gen 2 Prius? This is the only one I've ever been in. On this one at shut off there is a mild sort of shudder. If the car was moving you might think of it is a slight lurch, but the actual motion seems to be if anything in both directions in quick succession (forward then back or vice versa) - the car doesn't actually move as a result of the transition. Same thing at start up. If it happens on acceleration it almost feels like the engine is stumbling, but I think that is just the superposition of its usual engine lurch being interpreted by my brain as something it already knows about (engine stumble.) The motion seems to be a bit less once it warms up, but the difference is subtle and it might just be my imagination.

    My mother's Gen III is smoother than this. On that other car it is hard to tell by feel when the motor is on or off. But since it is a different model, perhaps not that informative. If this isn't right for a Gen2 what sorts of things could cause it? The car's only known problem is that the 12V battery seems to be quite weak. No warning lights are lit (or flash when the motor transitions).
     
  2. bisco

    bisco cookie crumbler

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    sounds about right, gen 3 is a little smoother. plus mileage matters.
     
  3. john1701a

    john1701a Prius Guru

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    That's normal. I remember that change. The reconfigure of the power-split-device along with the introduction of a two-speed setup (another PSD instead of a reduction-gear) made it smoother.
     
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  4. Graeme1949

    Graeme1949 Member

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    That is normal. I'm the original owner of a 2004, and it has been doing that all along. The only time it is really noticeable to me is when the vehicle is stopped. I have driven a couple of other cars (conventional, not hybrid) that have the engine stop when the vehicle is stopped for more than a few seconds, and they make the same type of shudder.


    -Graeme-
    2004 Prius with >190,000 miles.
    Sent ?.
     
  5. Graeme1949

    Graeme1949 Member

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    A "weak" 12 V battery is something that MUST be corrected ASAP. Otherwise you may go out some morning soon and find the car totally dead. (Like I did about 6 or 7 years ago.)

    Of course, Toyota in their wisdom made the battery a non-standard size, with non-standard size terminals, and with an electrolyte vapor exhaust tube that must be connected. (That's because it is inside the vehicle instead of in the engine compartment.) I have taken the easy way out and had the dealer do it. My car is on its third one now. (Note: the first time that battery died it had to be towed. The last time I had the dealer replace it when the car was there for something else.)




    -Graeme-
    2004 Prius with >190,000 miles.
    Sent ?.
     
  6. Moses Bruh

    Moses Bruh Member

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    Question about when your 12v battery died, if you had a new battery and brought it to ur prius and swapped it out then and there, it would have turned on fine and you could have drove right away?
     
  7. oil_burner

    oil_burner Active Member

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    you're feeling it on the older car because the engine and transmission are attached via 3 rubber mounts. As these age, the rubber softens and breaks down, and allows the engine to rock when it starts. try new engine mounts and you will be amazed at the difference.
     
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  8. Graeme1949

    Graeme1949 Member

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    I have no idea. In any case, with the car inoperable, I had no way to get anywhere except by hoofing it.

    -Graeme-
    2004 Prius with >190,000 miles.
    Sent ?.
     
  9. Graeme1949

    Graeme1949 Member

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    Interesting - thanks. I will look into that. (40 to 50 years ago I would have done that work myself. Not any longer ...)


    -Graeme-
    2004 Prius with >190,000 miles.
    Sent ?.
     
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  10. pasadena_commut

    pasadena_commut Senior Member

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    Thanks for the info.
     
  11. bisco

    bisco cookie crumbler

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    correct
     
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  12. tonybluegoat

    tonybluegoat Junior Member

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    I had this happen on mine. It got more and more "shuddery" to the point that it wouldn't restart sometimes (like at a light) and would throw a code for the throttle position sensor. In that instance my shade tree mechanic swapped the throttle assembly (?) for another one we had on hand and it cleared right up. 50k miles later (this car has 380,000 miles, 2nd engine, and a replaced new hybrid pack) it started getting rough again (no codes) so I had him clean the throttle body really good and it smoothed out.

    I'm not a mechanic. I have one. But I've put hundreds of thousands of miles on three different Gen II's. There are normal noticable transitions then there are "that doesn't sound right" engine transitions. I would think about cleaning the throttle body if it gets bad. Just my 2 cents.