1. The site is migrating to a new server this week, so there will likely be some downtime during that process. You can follow along here for updates.

2014 Prius sudden mileage drop and quickly gets into power mode acceleration leaving eco and ev

Discussion in 'Gen 3 Prius Fuel Economy' started by Dravid, Mar 21, 2021.

  1. Dravid

    Dravid New Member

    Mar 21, 2021
    2014 Prius
    Hello Prius chat, its the first time I’m posting here! This is Dravid
    My prius 2014 (84k miles) suddenly dropped its city mileage to 30 mpg. I had a very bad experience driving in houston, With a lot of potholes and quick accelerations to match the traffic there.
    The acceleration seems to be very touchy, the engine gets into power mode for even the slightest touch. Before this issue, on eco mode the engine used to be on eco bar at-least for a half gas pedal press.
    I have no idea what happened, another thing I noticed was a whistling sound from the hood when I raise the car on parking mode.
    On highways with cruise control, the mileage is around 40’s which is fine?
    The another thing was when I checked the hybrid system monitor, the electrical battery is only powering the vehicle for just 1 second then the gas engine starts doing the job, literally the battery seems to be in full bar and i guess its not being used at full capacity
    Please help me out :)
  2. vvillovv

    vvillovv Senior Member

    Mar 19, 2013
    2017 Prius Prime
    Prime Plus
    I'd suspect a vacuum leak - for the whistling sound from the hood when the car is raised on parking mode.
    not sure I understand that description, but if I did get the jist of it, I'd suggest taking a spray bottle of water with a teaspoon of dish soap and spray lightly on the rubber hoses to help find leaks if there are any.

    About the reduced city driving mileage, the hybrid computers adjust to the way the car is driven. If you have to continuously make fast acceleration to keep up with traffic flow in S Tex or anywhere for that matter, the car is possibly adjusting to it's drive cycles / trips / commutes. however you'd describe it. If my guess is close, I'd recommend trying to find a way to avoid heavy traffic for a few days at minimum and find a more relaxed pace to see if that helps the car re-adjust to more efficient use of the battery.

    Of course if there is a vacuum leak under the hood, that might be the reason for the battery not appearing to be working, or at least might be contributing to the problem.
    I can't think of any reason why a vacuum leak under the hood would make the battery appear to not be working right, but I also don't want to rule out any possibilities.

    Depending on what kind of hissing / whistling sound it is, it could also be the cooling system, check your coolant level and look for dripping coolant.
  3. bisco

    bisco cookie crumbler

    May 11, 2005
    2012 Prius Plug-in
    Plug-in Base
    maybe your hybrid battery going south. how many miles on her?