Engine instantly off when gas pedal released

Discussion in 'Gen 2 Prius Fuel Economy' started by f16bmathis, Sep 1, 2010.

  1. f16bmathis

    f16bmathis
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    I've had the EV mode switch installed since the day I bought my Prius. Its great for coasting down the hill when I first start out, or to move it around my garage / driveway. But yesterday, I wanted to see if I could make it home (2-3 miles, mostly downhill) in EV mode. So as I was driving, I puched the button, it beeped twice meaning it wasn't going to engage, and I pushed it again, just to show it who the boss was. The EV mode did not engage, but now everytime I let go of the gas pedal (car warm, under 45 mph, battery above 2 bars) the engine shuts off instantly!

    Normally, my engine will stay running till I've stopped for a few seconds, or if I'm on the brakes for a few seconds, under 35 mph, but it never shut down as soon as I was off the gas pedal.

    I usually average about 56 mpg driving 35-45 around my house, but yesterday I was averaging above 75! I even drove in a three mile circle to ensure it wasn't just from driving down hills. I continued to drive for 45 minutes and consistantly got better than 75mpg.

    I did it again at lunch today!

    Is this something we know about?
     
  2. ksstathead

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    If you are in Stage 4 operation, it should shut down below 42 mph when not needed for power. No clue why things changed for you. Above 42 mph it should spin with no fuel injected when no power needed.

    See the warming up stages or Five stages thread which should be stickied under gen2.
     
  3. f16bmathis

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    Maybe I have a problem then. Without pushing the EV mode button, it won't do it. It keeps the engine running except after I come to a complete stop, or if I've been slowing down for a long time.

    After pushing the EV mode button, it stops the engine right away as long as the gas pedal is released, its warmed up, and I'm going less than 45.

    So I'm not sure this fits into the stage four operation, or it should do it without pushing the EV mode button. If thats the case, my Prius doesn't work the way it should normally.
     
  4. bisco

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    if you're going by the mfd, in six years, my has always shut off immediately when i let off the gas, at any time in the the driving cycle stages. i realize it is still turning at higher speeds even if the powerflow doesn't show it.
     
  5. ken1784

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    My bet is you were in Stage-3. It is pretty normal.

    Ken@Japan
     
  6. 2009Prius

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    This is confusing. For other readers' benefit: The MFD shows only the powerflow, not engine ON/OFF. The engine may be ON even when there is no powerflow shown on the MFD.

    +1. Suggest the OP search and read articles on the Prius warm up stages. Good luck! :)
     
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  7. f16bmathis

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    Not using the MFD, I'm using a ODBII scan guage. But even then, like I said, without pressing the EV mode button the MFD will show the engine off, but everyone knows its idling, and my ODBII scanner shows 920 rpm, but if I depress the EV mode button once and get the double beep, then press and hold it for a few seconds, the engine shuts off immediately after letting go of the gas pedal. I've used almost half a tank of gas before discovering this, and averaged 52.3 MPG. Its been two days, and even on the drive home on the highway, as I need to slow for traffic, the engine shuts off. I averaged better than 70 MPG on my entire trip (16 miles) mostly highway, and my average MPG has allready risen to 53.? something.

    I was thinking of re-installing the EV mode switch from a momentary switch to an off/on switch and see if it'll keep me in the "engine off" mode
     
  8. f16bmathis

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    Does this stage 3 require the EV mode button? I'm bad at expressing what is going on I guess. Looks like most readers believe my engine is on and idling, and the MFD is showing the engine not running.

    I'm an Air Force retired Avionics Technician (F-111 and F-16). I've built my own EV Chevy S10. And I can tell you, I know that the engine is really off! Not only from seeing the ODBII, but also from hearing and feeling it turn back on, and my new gas mileage increase.. It kinda shakes the car slightly, more than just a car engine reving up from an idle. Plus I've allready been coasting and regening since I bought the car. This is different. The engine shuts off IMMEDIATELY when letting go of the gas pedal, so in effect, I'm only using gas to accelerate or maintain speed at above 45mph. Anything less and that engine is off.

    From what I've just read about the stages, this is something different. I believe (but dont know squat) that this is the way the enginer system works, except they use an on/off switch and of course have batteries to replenish the main pack as it depletes. With thier on/off switch, it stays in EV mode except when over 45 or accelerating beyond the packs capabilities.

    I'll test this theory by installing an on/off switch and will post results, maybe even do a youtube video so you can see what I'm talkling about.
     
  9. f16bmathis

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    I've found to engage this "engine off" mode, you have to press the EV mode momentary switch once, hear the double beep (EV mode not engaged) then press and hold the EV mode switch again for a few seconds. It also seems that you can disengage this mode by pressing it again. Then it'll act like a normal Prius.
     
  10. uart

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    Ok, if I'm reading this correctly then this seems like quite a find. It looks like the OP is saying that he can force his prius into stage-4 operation using only the EV-button (without needing the normal 5-10 second stop). If this is true then it's big news for everyone with the EV button. Has anyone else yet confirmed this finding?
     
  11. uart

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    OK I just tried and couldn't make it work. Got it nice and warm and into hybrid stage 3. Started a glide from about 53 km/h and predictably the ICE kept idling. Hit the EV button and it gave the double-beep refuse (again predictably as I was over 44 km/h) then held it in for several seconds - nothing happened. Tried again - nothing happened.

    Too bad, it would have been a nice find if it was true. Still would be good for others to test this out. Perhaps there are model differences or perhaps I missed something.
     
  12. Bob64

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    Uhh... Perhaps this is the first time you've gotten into stage 4?

    Look, the prius shuts off the engine when you release the gas pedal under 40mph if you've done the following conditions once:
    *coolant temp is >= 70c AND
    *you've idled for 7 seconds with the engine on at a speed below 7mph without applying the gas pedal.
     
  13. f16bmathis

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    Ah finally some's catching on that this is something different. The problem is, even I can't seem to figure out how to get it to go into this mode. I tried holding the EV mode switch in constantly but it didn't do it, seems my best way of getting into it is to press the EV mode button after the car has driven a while, though I've done it when cold, wait for the two beeps, then pushing the button another three times. Sometimes it works sometimes it does'nt, but you can tell it worked if the engine shuts down then start it up again by accelerating, and let go of the gas and it will shut off immediately again. The engine will only come on when accelerating moderatly, otherwise its pure electric or coasting / regening. I'm going to make a video and post it so we can see if anyone else can duplicate this and someone can tell me that I'm not nuts! :)
     
  14. f16bmathis

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    Nope. I've been in stage 4 plenty. In stage 4 the engine waits (7?) seconds before shutting off. Whatever I'm doing, it turns off immediately after letting go of the gas pedal.

    So if your in stage 4 and you want to coast down a hill, the motor never shuts off cause you have the gas pedal slightly depressed so your not regening. In the mode I'm desperatly trying to describe, when you want to coast down a hill, you let go of the gas pedal, the engine immediatly shuts off and you can then step on the gas pedal to coast with the engine off the entire time, till you want to accelerate beyond the electric mode capability.

    I will make a video and post it to you-tube and paste the link here. Then someone can let me know if I'm a loon, or if I actually found something.
     
  15. Bob64

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    No, the 7 second thing gets you INTO stage 4.

    After that (in stage 4), it'll turn off the engine immediately upon release of the pedal. (unless its recharging or doing something else that requires the engine to be on)

    Do this next time with your OBD scanner. Display the coolant temp. When it gets to 70c, then go to a complete stop with the engine running. Stop for 7 seconds (engine will turn off after 7 seconds). Once this happens, your in stage 4. Try accelerating hard to force the engine on, and then let go of the pedal. Chances are, the engine will come to a stop immediately.
     
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  16. F8L

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    That is how it works for me. :)

    Because I live very near a freeway, I often have not reached stage 4 before I enter the freeway and high speeds without a stop. I will try to monitor the engine more closely to see if it turns off immediately after gas pedal release. If it does not then I will try fooling around with the EV button and see if that makes a difference. In the mean time, I'm going to re-read that darn sticky to make sure I know what the hell I am talking about. It's been awhile since I reviewed the stages in depth. lol
     
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  17. uart

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    No that's not how it works. You need to read the following.

    http://www.techno-fandom.org/~hobbit/cars/five-stages.txt
     
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  18. Mike Dimmick

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    In my experience, 10 seconds of idling. The engine management computer has to go into idle mode, which as you say is at under 7mph, and it seems you have to be applying the brake hard enough that brake override happens.

    That's true for Gen 2. They've reportedly fixed the issue in the third-generation car, so it will idle the engine whenever you slow down in the same conditions, and if you slow down for long enough, not requiring engine power, it then goes into Stage 4.
     
  19. f16bmathis

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    OOOOHHHHHH!!!! I guess I had been driving to get to the freeway, warming the darn thing up, and pushing buttons, when for the first time I noticed it going into stage 4 after I had gotten off the highway and it was fully warmed up. So from there, I thought it was me pushing that darn EV mode button.

    Now I guess I'll start skipping the highway, cause I love that 75+ mpg!

    Thanks all! They need an icon with a light bulb above the head.
     
  20. f16bmathis

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    I figured it out today - finally! Sounds like I was doing like you were, but it worked for me. I had started the car and drove till temp was at 126 F, speed was under 35, I pushed the EV button once and it went into EV mode. I got over 35, it beeped as it went out of EV mode, temp was still 126, foot off the gas pedal, and I pushed EV mode again. It double beeped, and I pushed the button twice real quick. The engine shut off right away, was doing 37 mph.

    Pushing the EV button in stage 4 seems to pull it out and starts the engine. This should be easy to check.

    At the time, I thought it was just commanding it to enter stage 4 without actually having to stop, or have the car water temp above 180. I'm not sure what was going on, I've got to try it again.

    I also tried a toggle switch as the EV button, but leaving it on never did anything.