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gas engine on-off-on-off-on-off

Discussion in 'Gen 2 Prius Main Forum' started by jsorger, Mar 10, 2004.

  1. jsorger

    jsorger New Member

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    Just wondering if anyone else has experienced this:

    At a certain stoplight on my commute home (I just exited the freeway and am on a 5% of so grade) the gas engine almost always cycles on and off until I move. If I sit there for a minute, for example, it will turn on for 5 seconds, then off for 5. It repeats this until the light changes.

    It only happens in this specific situation, at this one stoplight. But it's fairly repeatable.

    Has anyone else had this happen?
     
    #1 jsorger, Mar 10, 2004
  2. Jerry P

    Jerry P Member

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    I've noticed that having the A/C on automatic in cold weather will cause the engine to do this sometimes, I suppose to provide heat to the cabin. If I switch it to manual, the engine will not act the same way.
     
    #2 Jerry P, Mar 10, 2004
  3. jsorger

    jsorger New Member

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    Good suggestion - I have noticed that before as well.
    But my AC is not on in this case...
     
    #3 jsorger, Mar 10, 2004
  4. cybele

    cybele New Member

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    Have you happened to notice how full the battery is?

    Sometimes when I'm completely warmed up the car will cycle on when I'm just sitting there and I've found it's when I have only two bars left.
     
    #4 cybele, Mar 10, 2004
  5. efusco

    efusco Moderator Emeritus
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    cybele's answer may be correct, or it could be just the opposite, that the battery is nearly full, the cycling will deplete the battery charge to avoid it getting too full should you have a long period of charging come up.
     
    #5 efusco, Mar 10, 2004
  6. DaveG

    DaveG Member

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    I've had it happen a couple times. I usually just turn on the front defroster for a minute or so and it stops the cycling.

    I also occasionally get a strange "surging" feeling while the engine is in park. Had it last night on a cold night as I was waiting for the car to defog the windows - almost as if the gas engine was idling a bit rough and the electric engine was having to try and pace it to run the power split device so as to keep the car stationary.

    Dave.
     
    #6 DaveG, Mar 10, 2004
  7. boa8

    boa8 New Member

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    #7 boa8, Mar 10, 2004
  8. jsorger

    jsorger New Member

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    Thanks, Boa8!
    That must be it. I must be at the angle where it turns on. Barely.
     
    #8 jsorger, Mar 10, 2004
  9. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Not neccesarily. I've had this too. Temp was just cool enough where the heater was on. I suspected it was either the heat at some threshold, or that my battery was full (it was) and it was dumping some charge.

    Hill hold does not use the ICE.
     
    #9 HTMLSpinnr, Mar 11, 2004
  10. charlieh

    charlieh Junior Member

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    I have found that my ICE in both the '03 and the '04 will come on if I am using the fan (with the A/C off, mind you). I guess the draw on the 12 volt causes the ICE to come on at a stop to charge the 12 volt. As soon as I shut the fan off the ICE goes back to sleep. The engine is so quiet that sometimes you don't even realize it is on. I added the Engine Run Light kit on my '03 sold by Coastal E Tech and am awaiting something like that from them for the '04. It serves as a visual reminder that the ICE is, in fact, running.
     
    #10 charlieh, Mar 11, 2004
  11. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Honestly, when used w/ the fan - the ICE doesn't cycle due to energy as much as it does to provide heat. The water pump for the ICE doesn't flow (much) when it's off. The 12V load can be handled just fine by the battery w/o the ICE unless the battery is down to 2-3 bars.

    In the case of the <'03, if on Defrost mode, the ICE would cycle for the A/C. It would also cycle the ICE if you requested higher heat and coolant temp was "warm enough" to not use the PTC's.

    In the case of >='04, it would only be for heat or battery drain.
     
    #11 HTMLSpinnr, Mar 11, 2004
  12. Price Taylor

    Price Taylor New Member

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    Yes, I have experienced what you are describing and it's annoying. I have also experienced the "engine rev" after descending a long hill.

    In the former case -- I'm not sure what the conditions are but will monitor that are report back to this group.

    In the latter case -- if you place the Prius in neutral, the rev problem goes away. The ICE is still running but it's not revving up to (my guess) over 2,000 rpm.

    Price
     
    #12 Price Taylor, Mar 11, 2004
  13. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Latter case is also illegal in most states. If the battery is full, it's not much harm as long as the ICE can spin enough to avoid overspinning MG1.

    In reality, leaving it in D and letting the HSD do it's job is the best bet. The engine reving is normal and not unnatural - and the ECU will not allow it to overrev.
     
    #13 HTMLSpinnr, Mar 11, 2004
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