Any thoughts on what to check for low MPG?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by '04Prius, Jan 8, 2021.

  1. '04Prius

    '04Prius Junior Member

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    That’s definitely true. I’m not super concerned about the actual battery pack yet, because what I’m seeing doesn’t remind me of a bad/weak battery, and the trouble code was more indicative of a sensor/ECU issue. I’m not seeing rapidly fluctuating state of charge or anything along those lines.

    I think what I need to do is fix whatever is causing the trouble code, and then reassess if something is wrong. Chasing O2 and MAF sensors and catalytic converters doesn’t make sense to me at this point.
     
  2. drone13

    drone13 Member

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    I would check the LTFT, A/F ratio sensor, and misfires since it's so easy to do with a BT adapter and a cell phone. I think before anything else make sure the ICE is running at expected A/F ratio and not going rich and wasting gas or enough misfires to make a difference (likely not on the misfires since that should throw a code). If the A/F is out of spec that would be the first thing I would tackle. If it looks good, then you can ignore ICE issues except maybe ECU since that is part of the same network the Batt ECU is on and they chat to each other. Check the connector at the engine ECU for corrosion. All the above shouldn't take more than 30 minutes and 1 beer. Good luck, I hope you can resolve it easily.
     
  3. edthefox5

    edthefox5 Senior Member

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    Given the parameters of the discussion grown up people would understand what I meant let it go.
     
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  4. kenoarto

    kenoarto Senior Member

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  5. edthefox5

    edthefox5 Senior Member

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    When in doubt I do a road test for mileage. Find a nice straight level road about 3 miles long.
    Set your cruise control for 60 miles an hour. Shut off lights and AC and radio and keep windows closed. Tires at 32.
    Reset consumption meter. Don’t touch anything.

    I get a solid 60 mpgs at the end of that 3 miles with my new NPB.
     
  6. dolj

    dolj Senior Member

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    Tires should be at least factory spec of 35 PSI Front/33 PSI Rear.
     
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