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Engine sputter/stutter

Discussion in 'Gen 2 Prius Main Forum' started by egullsfan, Sep 29, 2008.

  1. egullsfan

    egullsfan New Member

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    I drove on a field trip (I teach 4th grade) and the trip was 70 miles one way. It was about 90 degrees that day, and the elevation change is about 2000 feet over the 70 miles. I had 5 people in the car, 2 adults and 3 nine-year olds. The trip there was fine. I got right around 50 mpg with the AC on. 4 hours later, we go to leave. There is a steep uphill grade out of the state park, a one lane road where I could only go about 20 mph. I noticed the car seemed to be revving really high, and seemed to labor up the hill. As I crest the hill, the RPM's seem to stay the same, yet the car would not go any faster. I slow down to about 5mph, then start to go again. When I press on the gas, the car stutters(like I had an arching spark plug wire and was running on 3 cylinders). I couldn't get the car over 30 mph and that was a struggle. The battery monitor showed green, even after the hill (it was full green when I turned it off 4 hours earlier). The car continued to sputter every time I would press on the gas, but I could get it to stay at a fairly consistent 30 mph with even gas pedal pressure. After about 5 minutes, the sputtering stopped and the car seemed fine. The only weird thing I noticed was that the battery monitor stayed in the exact same position (didn't discharge or recharge), a little over half a charge, even though I was using and recharging the battery often in the next 10 minutes. By the time I got back to Sacramento, all was fine and I was still getting around 50 mpg still.
    The only thing I can think is that one of the students was leaning over on the battery air vent on the back passenger side of the car. Did the battery overheat??? Any help would be appreciated. The car has been fine ever since.
     
    #1 egullsfan, Sep 29, 2008
  2. removeum

    removeum Member

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    :cool:It is possible that the batteries were overheating. However, did you hear the fan come on and if you did not then the batteries did not become hot. You can always take it to dealer and ask them to check and see if it throwout a code that could be located by a scan tool.
     
    #2 removeum, Sep 29, 2008
  3. Bob64

    Bob64 Sapphire of the Blue Sky

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    Was this at a "high altitude" location?
     
    #3 Bob64, Sep 29, 2008
  4. daniel

    daniel Cat Lovers Against the Bomb

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    An overheated battery should not cause engine stutter. When the battery gets too hot the car will reduce its use of it, and mpg will suffer slightly as a result, but that will not affect how smoothly the engine operates.

    The engine will rev high on hard uphills, and that is normal. Because of the unique power train, the engine can run fast when the car is going slow. This provides electricity to MG2 via MG1 acting as a generator, providing a lot more torque than a conventional car would get at slow engine speeds. But you will be able to go normal highway speeds.

    What you describe, the stutter, and the real lack of power, sounds like an engine problem.
     
    #4 daniel, Sep 30, 2008
  5. dogfriend

    dogfriend Human - Animal Hybrid

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    The OP stated that the elevation change was about 2000 ft; Sacramento is not much higher than sea level, so the max elevation was about 2000 ft.

    My dad used to live between Placerville and Camino (elev ~2600 ft); I have not experienced what the OP described driving up to Placerville or even at higher elevations (Lyons Creek Trailhead and Echo Summit > 7200 ft)

    I have noticed that use of the AC in stop and go (or stopped) traffic conditions can run the HV battery down pretty quickly. When the battery gets depleted (purple bars on the MFD), the car will protect from further discharge and will rely more on the ICE with higher ICE speeds and lack of torque from MG2. I wonder if this was the cause of the problem?
     
    #5 dogfriend, Sep 30, 2008
  6. egullsfan

    egullsfan New Member

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    It wasn't real high altitude driving, maybe 2000 feet above sea level. I'll check to see if it threw any codes. It is just so weird, it drives fine now.
     
    #6 egullsfan, Sep 30, 2008
  7. richard schumacher

    richard schumacher shortbus driver

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    Any chance you were in "B" and not "D"?
     
    #7 richard schumacher, Sep 30, 2008
  8. AbuLafya

    AbuLafya New Member

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    I had these same symptoms more than once.
    It only happened in relatively high altitude (Lake Tahoe area), when temps were not cold.

    What I think happens is that the smart powertrain system gets confused. It only happens in very slow speeds, i.e. starting from 0 and speed < 10 MPH.
    Since the gas pedal is "drive by wire" the gas engine revvs for less than a second and then incorrectly revvs down. The car barely manages to climb the grade and the driver presses the pedal harder, which does not do anything. Releasing the pedal and trying again more "gently" produces some result but barely making any progress.

    After the grade is over, or speed increases, everything is back to normal.

    Is there a "software update" we can get?
     
    #8 AbuLafya, Jul 13, 2009
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