Normal CVT behavior?

Discussion in 'Gen 2 Prius Technical Discussion' started by PriusGuy32, Sep 16, 2012.

  1. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Ive never had a CVT before and am wondering if this is normal...

    I have to back out of my driveway at my house. After I back out, I stop, put the car in drive. If I let go of the brake the car starts to move but slow at first then it kicks in like it was halfway in drive and completing the "shift" (I realize CVT's dont 'shift' but I cant think of a better way to put it). It feels like its taking a few seconds to go fully into Drive when first shifted into it.

    The car has 53,500 miles on it and had the 50,000 miles transmission fluid change at the dealership.

    Is this behavior normal?
     
  2. Munpot42

    Munpot42 Senior Member

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    When you are in reverse it is always driven by the electric motor, never the gas engine, my gas engine usually start up halfway up my driveway. When I put it into drive it usually smoothly pulls forward on electric. My first turn is up a hill and about a third of the way up the hill the gas engine takes over, usually with a little jerk, perfectly normal. Sounds like yours is doing the same thing?
     
  3. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Hmmm... I will have to do more observation.

    Its like when I first put it in drive after reversing, if I press the gas it hesitates for a minute; gas or electric. Like the CVT is still working on fully engaging and Im prematurely rushing it. Although I give it like 2-3 seconds after I place it in drive to drive away (a long time when you are pulling out onto a busy road!).
     
  4. edthefox5

    edthefox5 Senior Member

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    Your on just battery at that point and then the engine starts when you start to speed up. Start looking at the Energy Meter on the MFD which tells you what your running on either hybrid battery or engine. Its very clear.

    And being familiar with and understanding the Energy and the Consumption screens are the first step in learning how to achieve max gas mileage.
     
  5. HaroldW

    HaroldW Active Member

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    The best way to drive a Prius when warm ICE is to stay in EV mode up to about 30 mph before kicking the ICE on. This way the electric motor does the hard work saving gas?;) H
     
  6. edthefox5

    edthefox5 Senior Member

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    Which is hard to do if there are cars behind you and you don't want to create alot of road rage as you pull away from
    the light at a snails pace. By the way EV doesn't save you much gas if any at all. The engine still has to run to charge the battery back up. It does have its place though to burn off the battery when its in the green.
     
  7. HaroldW

    HaroldW Active Member

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    I have no problem with doing it, and it is not really that slow. I don't worry about the other cars behind as they can pass! I worry about what I pay for gas. EV does save lots if used in the way I mentioned, but it helps if you can time stop lights better!:) H.
     
  8. a priori

    a priori Canonus Curiosus

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    Is this something new you've noticed, or has the car behaved this way since the beginning?

    By the way, the power split device in the HSD is not really a CVT. Even so, I don't follow why you are tying the behavior to a CVT. What about the situation has you linking the issue to the transmission? Does it feel like it would if the clutch plate were slipping on a car with a different transmission?
     
  9. 2009Prius

    2009Prius A Wimpy DIYer

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    Yes I agree max fuel economy is achieved when the HV battery is used the least, so as to minimize conversion loss.

    Well AFAIK this method/technique has never been mentioned/reported by other reputable Prius hypermilers. Do you have data to show that this technique works better than the conventional pulse-and-glide technique?
     
  10. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Well I just got the car this past Friday (3 days ago) and have only logged about 150 miles on it, so I cant say if its "always done this" but I sure did notice it.

    It reminds me of a regular automotive 3-4 speed transmission. When you back up out of a spot or driveway, stop and put it in drive, you usually (well on most cars) cannot mash the gas that very same instant you just put it in drive. It will usually slip-bang into drive because its still transitioning (hydraulic transmissions Im referring to), not to mention its bad for a traditional transmission to do such. So most of us come to a complete stop when shifting (including myself) from R to D.

    When I back out of the driveway or a spot with my Prius, I stop completely, put it in D and take my foot off the brake. It doesnt start moving for like 2 seconds. And when I press the gas finally, it feels like its still making the transition into Drive.

    Has nothing to do with the ICE. Its not even running or even close to kicking in when this happens. I just didnt know if this was normal or not. It seems the "transition" to start moving forward when put in Drive is a lot quicker on traditional non-hybrid cars that Ive owned.
     
  11. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    In my experience, D is instantly available.
     
  12. HaroldW

    HaroldW Active Member

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    2009Prius:
    One of the best in the US uses this method always when starting from a start. He also teaches it.His name is Wayne. H
     
  13. a priori

    a priori Canonus Curiosus

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    There is no delay or any lock-out when changing from reverse to drive. I've changed the indicator while the car is still moving. The computer will figure out how to manage my request.

    It could be that you are dealing mainly with the fact the pedal response is rather attenuated. The car is designed to maximize fuel economy, so it will not press the ICE into full-out use unless you really mash the pedal to the floor. Even so, the response will have as much to do with the state 0f charge of the battery as about anything else.

    The other part of this is that the computer is waiting on some input from you. If you are waiting for two seconds on a response from the ICE, the computer is waiting on you to tell it what you want and how quickly you want it. The design is intended to mimic an automatic transmission, so there will be a slight tendency toward propulsion without pressing your foot on the accelerator, just as there is a slight decrease in speed and deceleration when you take your foot off of the accelerator. However, simply putting the car into "drive" mode does not mean the same as connecting it up to the hp equivalency of the ICE. The latter would be the setup in cars with automatic transmissions linking ICEs and the driveshaft.
     
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  14. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Well Im not even talking about pressing the gas yet or using the ICE.

    If I put the car in drive and let go of the brake, theres a 2-3 second delay until it starts even moving. If I give it any amount of gas, it feels like its still engaging Drive. How about slipping while engaging the car into drive, that might be a better term. Once in drive its great though and theres no weirdness.

    I think Ive thoroughly confused everybody and probably my best bet is to go to a dealer and find a used Prius of my vintage (2007) and miles and test drive it to see if it does the same thing. Maybe its normal behavior and Im just panicky because I just bought a used car with no warranty except the hybrid component warranty.
     
  15. a priori

    a priori Canonus Curiosus

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    No reason to panic! You'll be fine.

    Have you become accustomed to the fact the car starts in battery/EV mode before the ICE turns on? There is a what appears to be a slight delay in the start of the gas engine, but that is because the initial response is from the electric motors.

    Have you tried starting out by just gunning it? Does the response change?
     
  16. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Ha. Im totally cool with the EV/ICE transition, and not at all what Im referring to in this thread. Which by the way, my ICE seems to have a rough idle sometimes but I guess thats a different topic..lol.

    The only time Ive actually floored it was on the highway. Ive never started out that way. I always try to be really gentle so I can ramp up the cold ICE slow and easy.

    It did it today and heres another way I can describe it - it seems when I put the Prius in Drive and take my foot off the brake, it feels like a brake is sticking or hanging up and takes a few seconds to release before the car starts to move.
     
  17. a priori

    a priori Canonus Curiosus

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    Interesting. I don't want to make any rash judgments, but it is possible the rear drums are sticking a bit. Have you ever used the parking/emergency brake?

    Some people have noticed this only because of a drop in fuel economy. Do you have any idea what kind of mileage you are getting at present?
     
  18. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Well I filled up today and was averaging 48.7mpg. After I filled up and reset the MFD mileage average, Im now getting 53mpg.

    Good point though. When I was in the service menu the other day to check the voltage on my 12v battery, I tested the parking brake to see if the MFD would acknowledge it. It didnt. I wonder if it is sticking...hmmmmm

    I should add it "feels" like its coming from the front end. And it ONLY does this when going from Reverse to Forward. If I stop for a red light and accelerate, it doesnt do it. It seems like either using the brakes in reverse OR shifting from R to D precipitates the issue.
     
  19. edthefox5

    edthefox5 Senior Member

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    It should "creep" immediately when put in D. My 07 creeps real good. Toyota software does that to mimic a regular car so people would not complain its just sitting there. But apparently yours is just sitting there. Not normal.
    Probably a brake hanging up. Go find an area with a slight hill. Stop on it and put it in neutral and see if it rolls OK.
     
  20. 2009Prius

    2009Prius A Wimpy DIYer

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    Well I have visited his web site quite a few times and attended one of his seminars in person. I don't remember reading or hearing about such method. Maybe I am getting old and start to forget things. :)
     
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