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2006 Prius occasional sluggishness and low MPG

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by actstenthiryfour, Dec 24, 2021.

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  1. actstenthiryfour

    actstenthiryfour Junior Member

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    Vehicle:
    2006 Prius
    Model:
    N/A
    I've had a 2006 Prius for about 6 months now - it's got over 200K miles and mostly runs great at around 50 mpg. However, I've noticed occasions where it enters a mode were the motor seems weak, mpg drops to around half, and the car is sluggish. All these episodes are temporary and follow periods of hard work, for example:
    * After driving 400 miles
    * After driving 380 miles
    * After going down a hill, reving the engine high in B mode, then climbing to the top of a steep hill

    I have check most all the basics, I believe:
    * Oil level seems fine
    * Cleaned the MAF sensor
    * Inverter coolant bubbling
    * HAV Battery seems mostly good
    * 12V battery is new
    * Fitlers cleaned

    I had a mechanic run Techstream on it, and the only code I got was: "Low DC input voltage". He checked the terminal of the battery, and afterward, the car was running great, until I drove to Arizona which is about 400 miles each way. Then I encountered the temporary sluggish behavior.

    My best guess would be something like an overheating transmission - it almost feels like the car won't shift into a high enough gear.

    Any ideas?
     
    #1 actstenthiryfour, Dec 24, 2021
  2. JC91006

    JC91006 Senior Member

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    Have you ever changed your spark plugs and coils?
     
    #2 JC91006, Dec 24, 2021
    actstenthiryfour and Another like this.
  3. SFO

    SFO Senior Member

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    What does your SOC (state of charge on the MFD) look like when you encounter this behavior?

    Is your HV battery still the original OEM, or something else?
     
    #3 SFO, Dec 25, 2021
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  4. Another

    Another Senior Member

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    I vote to change plugs and coils
     
    #4 Another, Dec 25, 2021
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  5. ammdb

    ammdb Active Member

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    If during this sluggish time the battery is at full bars and the engine keeps running and charging it anyway, then the hybrid system is going into a mode where it purposely overcharges the pack to rebalance all the cells. Before I got a new pack this would happen after driving my car aggressively, like having to stomp on the gas to maneuver in heavy traffic at highway speeds. Not sure if this is the case on newer Prius generations.
     
    #5 ammdb, Dec 25, 2021
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    Model:
    Four
    I would suggest getting the Dr Prius and Hybrid Assistant (on android) apps with a compatible OBD2 bluetooth adapter then you can monitor temperatures of the car's systems (such as HV battery, inverter, or motors) and see what happens when you feel the performance drop.

    Posted via the PriusChat mobile app.
     
    #6 mr_guy_mann, Dec 25, 2021
  7. actstenthiryfour

    actstenthiryfour Junior Member

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    Vehicle:
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    N/A
    No I haven't. I think I assumed the dealer would alert me if there were any issues - I'll try to confirm that.

    Thanks, I tend to think that idea is probably my best hope.

    That's an interesting idea - I've noticed this phase occurs after pushing it.

    Thanks, I'll check on it.

    Thanks for the input. Now, it seems to always be in a low-mileage state as it goes through it's normal charging on the MFD. The HV battery is the original, and seems generally fine. I notice at times it goes to two bars seemingly out the blue, then charges up again to normal. A Prius mechanic said the battery was holding charge well about a month ago.
     
    #7 actstenthiryfour, Jan 26, 2022
    Last edited by a moderator: Jan 26, 2022
  8. bisco

    bisco cookie crumbler

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    do you know anything about the maintenance history?

    any dealer maintenance can be found at toyota.com/owners
     
    #8 bisco, Jan 26, 2022
  9. SFO

    SFO Senior Member

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    This is a sign of a failing HV battery, now would be a great time to balance/recondition it by using a "grid charger" set up.
     
    #9 SFO, Jan 27, 2022
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