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ICE runs unnecessarily

Discussion in 'Gen 2 Prius Main Forum' started by Orf, Dec 10, 2007.

  1. Orf

    Orf New Member

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    2006 I-Tech Prius, 17,000 km, a/c and radio turned off.
    My Prius has developed a new symptom which I first noticed about a week ago.
    On a day when the air temp was about 20ºC I drove about 100 km and then went down a long hill that produced all green bars on the MFD. Drove up a small hill and arrived at a turn-off showing one less green bar. Drove along a flat road for about 100 yards at about 30 km/hr and lifted my foot of the accelerator to slow down. Green arrows appeared on the MFD and at the same time the fuel consumption showed 2.4 L/100km.
    Next day the same trip gave the same results. I went round the block (no long down hill run) - same result.
    Today in a different location I noticed that I had all green bars so I took my foot of the gas and the MFD showed a fuel consumption of about 2 L/100km. This time I selected EV mode and the consumption dropped to zero. Turned off the EV mode and the fuel consumption immediately rose to 2 L/100km. The engine would have been hot and I had all auxiliaries that could be turned off, turned off.
    Before I take my car to Toyota for testing, I thought I would ask if anyone could explain this symptom. Note: It is summer here so severe cold does not apply.
     
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Could there be a problem with your aux battery and the engine is staying on the charge it? Not sure if that is how it works but some posts seemed to imply that.
     
  3. Bob64

    Bob64 Sapphire of the Blue Sky

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    Your still not in stage 4. This means that the engine temp has not reached 70C yet. Thus the engine is stuck in stage 3a "warmup" mode. (If the engine reaches 70c, you MUST stop for 6 seconds while the engine is running to enter stage 4)
     
  4. Orf

    Orf New Member

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    I would have thought the engine was warm enough. I have travelled the same route in much colder conditions without problems.
    However, I will try the stopping for 6 secs to see if that makes a difference.
     
  5. Orf

    Orf New Member

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    The aux battery is holding a good charge so I doubt that this is the cause. However, you never know so I will take more note of the battery condition.
     
  6. efusco

    efusco Moderator Emeritus
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    Yea, the engine being warm enough is only one part. Why it was chosen to program the car this way is anyone's guess, but you have to do the full stop for 6 seconds AFTER warm-up to get into S4. Once you do that you'll stay in S4 until your next shut down cycle.
     
  7. F8L

    F8L Protecting Habitat & AG Lands

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    I should have read your post more thoroughly. I didn't think of the Stage4 issue. Hopefully that is your problem. :)
     
  8. Orf

    Orf New Member

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    I drove out of my yard this morning (temp 19ºC) and noted that the MFD showed all green bars. After 200 yards I took my foot off the accelerator and the fuel consumption dropped to zero. I did this 3 times all with the same results.
    After 200 yards I would have thought the ICE would still be cold yet it turned off. I travelled about 1 km and by that time the green bars had turned to blue. Out of curiosity I lifted my foot and the ICE once again turned off.
    I was surprised that the ICE turned off before the it warmed up. Is this normal?
    Where can I read about stage 3a and 4 driving?
    I am beginning to wonder if this odd condition is the cause of different fuel consumption figures over an ofen travelled route. Previously I thought it was affected by the wind or load in the car.
     
  9. jhall

    jhall New Member

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  10. Orf

    Orf New Member

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    Thanks, jhall.
    Having now read Bill Merchant's article on the 5 stages of operation I am more confused than ever.
    Going back to my initial post, I did stop at a stoplight for at least 10 seconds (more like 30-40 secs) before climbing the hill and turning into the place where I first noticed the ICE running when my foot was off the accelerator. According to the article, I should have been in stage 4 but it seems I was not.
    In my last post, I should have been in stage 1 because the ICE had not warmed up but it seems I was not because the ICE shut down when I lifted my foot off the accelerator. I doubt that I was in stage 2 after only 200 yards.
     
  11. Bob64

    Bob64 Sapphire of the Blue Sky

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    keep in mind that the prius WILL turn off the engine while in stage 3a if your traveling at speeds above 35mph (and if the temp is 70c+).
     
  12. partipilo

    partipilo Weirdo

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    Thanks for the link to the stages of operation. I kinda felt that there were some stages present - whenever starting up and the ICE kicks in and I drive away, the engine never revs up, it feels like its running on battery even though the ICE is on.