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2008 Strange engine activity

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jakem, Jul 24, 2011.

  1. jakem

    jakem New Member

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    Just got my Prius about 2 weeks ago. It's a 2008 model with about 65,000 miles on it. I've been having several problems.

    The Maintenance Required light was on all last week until I reset it with instructions from the dealer: hold OBO/Trip button on startup until the the dashes on the screen go away.

    This all worked until I realized the air conditioning fan had completely shut down. No air coming out of any vents. I followed the instructions on this board on how to fix it. I took off all the things blocking the fan motor (transmission control, cover, etc), gave the fan a spin, put it all back together, and the fan motor started blowing again.

    Now the car just seems to be driving funny overall. The engine not shutting off, extremely low mileage on flat roads, a too-loud acceleration sound, resistance accelerating to minimal speeds (35-40). What is going on?? Did I leave something unplugged below the dashboard?? :Cry:
     
    #1 jakem, Jul 24, 2011
  2. F8L

    F8L Protecting Habitat & AG Lands

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    What is the SOC, state of charge, read when you are experiencing this laggy acceleration? Are your using the AC alot while driving in stop and go traffic? Have your check the voltage on your 12v battery?
     
    #2 F8L, Jul 24, 2011
  3. bisco

    bisco cookie crumbler

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    did you unplug something below the dashboard? i second the 12v although 08 is a little early, it is a possibility.
     
    #3 bisco, Jul 24, 2011
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    It could be something you didn't reconnect, causing the poor performance.

    And per F8L, a bordline 12 volt battery might be causing the performance problems. If you hook up a digital voltmeter, a healthy battery would give a reading of around 12.6~12.8 volts. That's as long as you haven't recently tried charging it. If you have, it would be best to drive it for a day before taking a reading, otherwise it will read high, but that's just transient charge.

    Also, did you deal with the maintenance required by the light?

    If the 12 volt is ok, maybe throw in the towel and get a dealership to look at it? Let them know about the work you did to get the fan going, that might provide clues.
     
    #4 Mendel Leisk, Jul 24, 2011
  5. direstraits71

    direstraits71 Member

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    The maintenance light just comes on every 5000 miles after it was last reset. and is a reminder to change oil. It doesn't indicate anything else.
     
    #5 direstraits71, Jul 24, 2011
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  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If you don't see any warning lights on then I doubt that anything important was left unplugged.

    There are a few things that you can try:

    1. Disconnect the 12V battery negative terminal for 5 minutes, then reconnect. The point of this is to give the ECUs a fresh reboot.

    2. Check the condition of the 12V battery. After resting overnight, measure the voltage while the car is IG-OFF. If much lower than 12.6V, then charge it overnight (or replace the battery if the voltage doesn't come back up after being charged and then having another period to rest.)

    3. Check tire pressure and set it at 44/42 psi front/rear.

    4. Check wheel alignment and correct as needed.

    5. Raise up the rear axle, release the parking brake, and check to see if the rear wheels spin freely.

    6. Check the engine air filter and replace if you cannot see light when holding the filter up to sunlight. The dirty side is on the bottom.

    Good luck.
     
    #6 Patrick Wong, Jul 24, 2011
  7. jakem

    jakem New Member

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    I just finished checking the voltage of the 12v battery, here's what I found:

    According to the onscreen Maintenance Mode, the voltage is 12.3/12.4 when no lights are on, and 11.8/11.9 when I turn on the headlights. Checked manually through a voltmeter, it measures about 12.65 volts. That seems pretty normal to me.

    So if it's not the 12v battery, what could it be?
     
    #7 jakem, Jul 24, 2011
  8. F8L

    F8L Protecting Habitat & AG Lands

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    The 12v battery appears fine. Did you perform the other checks that Patrick posted?
     
    #8 F8L, Jul 24, 2011
  9. seilerts

    seilerts Battery Curmudgeon

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    How many battery bars do you normally have on the display? Can you hear the HV battery fan running? Its inlet is on the passenger side top corner of the back seat.
     
    #9 seilerts, Jul 24, 2011
  10. jakem

    jakem New Member

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    Basically I just think that the engine is working too hard to accelerate to fairly low speeds. Almost like the car gets to a steady speed of about 30mph and the engine doesn't let the battery take over, so the mileage caps at around 25mpg.

    The battery is usually in the blue (medium) phase. Very rarely does it become red or green.

    And no, I can't hear anything coming out of the HV battery vent.
     
    #10 jakem, Jul 24, 2011
  11. firepa63

    firepa63 Former Prius Owner

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    How long are the trips you are taking? If they are just short trips the MPG will be low. The first 5-10 minutes of driving are the worst for mileage.
     
    #11 firepa63, Jul 24, 2011
  12. seilerts

    seilerts Battery Curmudgeon

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    Okay, if you have 3-5 bars, then you should get some action from the battery when you accelerate. If it were at one bar, then it is normal to hear the engine wind up to very high rpm. If you can hear the HV battery fan running, then the HV battery is HOT, and it is also normal for boost/regen to be inhibited. It may still be that the HV battery is hot, i.e. the HV battery fan is clogged, but hearing it run would at least have been an obvious clue.
     
    #12 seilerts, Jul 24, 2011
  13. jakem

    jakem New Member

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    I definitely hear something running under the car. It's like a high-pitched whirring noise on the left side of the car. When I turn off the AC though, it stops.

    And the HV fan isn't running, at least not from the vent in the back seat.
     
    #13 jakem, Jul 24, 2011
  14. seilerts

    seilerts Battery Curmudgeon

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    Yeah, the jet turbine sound is the A/C compressor. It runs off the inverter, rather than the engine.
     
    #14 seilerts, Jul 25, 2011
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